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Journal articles on the topic 'Natural history, southern hemisphere'
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1
Butt, Nathalie. "Geographical bias constrains global knowledge of phenological change." Pacific Conservation Biology 25, no. 4 (2019): 345. http://dx.doi.org/10.1071/pc18073.
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Climate change is already driving shifts in phenology, the timing of life-history events such as flowering, fruiting, egg-laying, birth, and migration, and this is set to increase. Although climate change is happening, and will continue to happen, globally, most of our ecological knowledge around its potential impacts on phenology is derived from temperate areas and ecosystems in the Northern Hemisphere, and information from the Southern Hemisphere is greatly lacking. This would not be a problem if biomes, ecosystems, species assemblages and species were the same in the Northern and Southern Hemispheres, but as they, in fact, differ across many factors and scales, understanding gained from one hemisphere is not necessarily applicable to the other.
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Cuffey, Kurt M., Gary D. Clow, Eric J. Steig, et al. "Deglacial temperature history of West Antarctica." Proceedings of the National Academy of Sciences 113, no. 50 (2016): 14249–54. http://dx.doi.org/10.1073/pnas.1609132113.
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The most recent glacial to interglacial transition constitutes a remarkable natural experiment for learning how Earth’s climate responds to various forcings, including a rise in atmospheric CO2. This transition has left a direct thermal remnant in the polar ice sheets, where the exceptional purity and continual accumulation of ice permit analyses not possible in other settings. For Antarctica, the deglacial warming has previously been constrained only by the water isotopic composition in ice cores, without an absolute thermometric assessment of the isotopes’ sensitivity to temperature. To overcome this limitation, we measured temperatures in a deep borehole and analyzed them together with ice-core data to reconstruct the surface temperature history of West Antarctica. The deglacial warming was 11.3±1.8∘C, approximately two to three times the global average, in agreement with theoretical expectations for Antarctic amplification of planetary temperature changes. Consistent with evidence from glacier retreat in Southern Hemisphere mountain ranges, the Antarctic warming was mostly completed by 15 kyBP, several millennia earlier than in the Northern Hemisphere. These results constrain the role of variable oceanic heat transport between hemispheres during deglaciation and quantitatively bound the direct influence of global climate forcings on Antarctic temperature. Although climate models perform well on average in this context, some recent syntheses of deglacial climate history have underestimated Antarctic warming and the models with lowest sensitivity can be discounted.
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Rosenfeld, Sebastián, Claudia S. Maturana, Hamish G. Spencer, et al. "Complete distribution of the genus Laevilitorina (Littorinimorpha, Littorinidae) in the Southern Hemisphere: remarks and natural history." ZooKeys 1127 (November 2, 2022): 61–77. http://dx.doi.org/10.3897/zookeys.1127.91310.
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Littorinid snails are present in most coastal areas globally, playing a significant role in the ecology of intertidal communities. Laevilitorina is a marine gastropod genus distributed exclusively in the Southern Hemisphere, with 21 species reported from South America, the sub-Antarctic islands, Antarctica, New Zealand, Australia and Tasmania. Here, an updated database of 21 species generated from a combination of sources is presented: 1) new field sampling data; 2) published records; 3) the Global Biodiversity Information Facility (GBIF) and The Atlas of Living Australia (ALA), to provide a comprehensive description of the known geographic distribution of the genus and detailed occurrences for each of the 21 species. The database includes 813 records (occurrences), 53 from field sampling, 174 from the literature, 128 from GBIF, and 458 from ALA. West Antarctica had the highest species richness (8 species), followed by sub-Antarctic islands of New Zealand (4 species) and the south-east shelf of Australia (4 species). The provinces of Magellan, New Zealand South Island, and sub-Antarctic Islands of the Indian Ocean include two species each. This study specifically highlights reports of L. pygmaea and L. venusta, species that have been almost unrecorded since their description. Recent advances in molecular studies of L. caliginosa showed that this species does not correspond to a widely distributed taxon, but to multiple divergent lineages distributed throughout the Southern Ocean. Ongoing molecular and taxonomic studies are necessary for a better understanding of the diversity and biogeography of this genus.
4
Simon, Christian. "Naturschutz und Naturgeschichte um 1900. Der Beitrag der Basler Vettern Sarasin." Gesnerus 71, no. 1 (2014): 72–97. http://dx.doi.org/10.1163/22977953-07101003.
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Conservation and Natural History around 1900: The Contribution of the Sarasin Cousins. Some basic concepts for the creation of the Swiss National Park were derived from observations made in Sri Lanka, Indonesia and New Cale donia. European researchers feared that the study of «virgin nature» would no longer be possible, as various species would soon become extinct under the combined influences of colonial practices and profit-oriented capitalism. While the motives for protecting nature originated from experiences made in the southern hemisphere, their scientific concept of conservation was based on European natural history and the related theories of evolution. In the light of this approach, endangered zoological and botanical species as well as «primitive» varieties of man were appreciated as «documents» to be preserved within their original environment for future scientific reference and research. Museum collections and reservations (parks) were two types of repositories connected to each other by the same objective.
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Hurwood, David A., Mike P. Heasman, and Peter B. Mather. "Gene flow, colonisation and demographic history of the flat oyster Ostrea angasi." Marine and Freshwater Research 56, no. 8 (2005): 1099. http://dx.doi.org/10.1071/mf04261.
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The Australian flat oyster Ostrea angasi is currently being assessed for its potential as a species for culture in New South Wales. It is considered important to determine the population genetic structure of wild stocks among estuaries before translocation of juveniles (spat) for growout in order to avoid possible deleterious effects of hybridisation of genetically divergent stocks (i.e. outbreeding depression). Five estuaries were sampled in southern New South Wales as well as another four from across the natural range of the species in Australia. Sequence analysis of a 594 base pair fragment of the mitochondrial cytochrome oxidase I gene was used to determine the degree of population structuring inferred from pairwise ΦST estimates and spatial analysis of molecular variance analysis. The analyses revealed that there is no significant genetic differentiation among the sampled New South Wales estuaries (P > 0.05) and all eastern samples represent a geographically homogeneous population. This essentially removes any potential constraints on broodstock sourcing and spat translocation within this region. Although levels of differentiation among all sites varied, little divergence was evident across the entire range of the sample. Furthermore, the study revealed extremely low levels of divergence between O. angasi and its northern hemisphere congener, O. edulis, raising the possibility that O. angasi may have only recently colonised Australian estuaries.
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Pelegrín, Jonathan S., and Carolina Acosta Hospitaleche. "Evolutionary and Biogeographical History of Penguins (Sphenisciformes): Review of the Dispersal Patterns and Adaptations in a Geologic and Paleoecological Context." Diversity 14, no. 4 (2022): 255. http://dx.doi.org/10.3390/d14040255.
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Despite its current low diversity, the penguin clade (Sphenisciformes) is one of the groups of birds with the most complete fossil record. Likewise, from the evolutionary point of view, it is an interesting group given the adaptations developed for marine life and the extreme climatic occupation capacity that some species have shown. In the present contribution, we reviewed and integrated all of the geographical and phylogenetic information available, together with an exhaustive and updated review of the fossil record, to establish and propose a biogeographic scenario that allows the spatial-temporal reconstruction of the evolutionary history of the Sphenisciformes, discussing our results and those obtained by other authors. This allowed us to understand how some abiotic processes are responsible for the patterns of diversity evidenced both in modern and past lineages. Thus, using the BioGeoBEARS methodology for biogeographic estimation, we were able to reconstruct the biogeographical patterns for the entire group based on the most complete Bayesian phylogeny of the total evidence. As a result, a New Zealand origin for the Sphenisciformes during the late Cretaceous and early Paleocene is indicated, with subsequent dispersal and expansion across Antarctica and southern South America. During the Eocene, there was a remarkable diversification of species and ecological niches in Antarctica, probably associated with the more temperate climatic conditions in the Southern Hemisphere. A wide morphological variability might have developed at the beginning of the Paleogene diversification. During the Oligocene, with the trends towards the freezing of Antarctica and the generalized cooling of the Neogene, there was a turnover that led to the survival (in New Zealand) of the ancestors of the crown Sphenisciform lineages. Later these expanded and diversified across the Southern Hemisphere, strongly linked to the climatic and oceanographic processes of the Miocene. Finally, it should be noted that the Antarctic recolonization and its hostile climatic conditions occurred in some modern lineages during the Pleistocene, possibly due to exaptations that made possible the repeated dispersion through cold waters during the Cenozoic, also allowing the necessary adaptations to live in the tundra during the glaciations.
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Lopez, Tanya Marie, Rajesvaran Nagarajan, and Sobana Swarta Thevi. "Biodiversity: Implementation of the 1992 CBD in Malaysia†." International Journal of Legal Information 40, no. 1-2 (2012): 273–308. http://dx.doi.org/10.1017/s0731126500006508.
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Of late, particularly since the inception of the Convention on Biological Diversity (“CBD”), there has been some recognition of the relevance of biological resources and the need to protect and conserve these resources for the benefit of humankind. Natural disasters which have been occurring around the world, such as the recent earthquake in Christchurch, New Zealand, the 2009 earthquake in Haiti, the floods in Pakistan and the mystery surrounding the fallen dead birds from the sky en masse in Arkansas have raised concerns on the state of the environment in which we live in today. The resultant long-term effects of such natural disasters is colossal to the inhabitants of mother Earth although those who are not directly affected by such disasters are rarely of the view that they have, in some way, contributed to the happenings of such disasters. In Europe and parts of America, winter temperatures plummeted towards the end of 2010 recording some of the lowest temperatures in history whilst in the southern hemisphere, cyclones and floods have plagued Australia thereby giving rise to prophecies that perhaps, the world may be coming to an end.
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Lepeco, Anderson, and Rodrigo Barbosa Gonçalves. "Bayesian and parsimony phylogeny of Augochlora bees (Hymenoptera: Apoidea) based on morphology: insights for their biogeography and natural history." Arthropod Systematics & Phylogeny 80 (March 4, 2022): 99–115. http://dx.doi.org/10.3897/asp.80.e71943.
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Augochlora Smith, with 127 valid species, is the most widespread genus of Augochlorini bees, ranging from Argentina to southern Canada, including the Caribbean islands. The genus is divided into three subgenera, Augochlora s. str., Oxystoglossella Eickwort, and the fossil Electraugochlora Engel. The extant subgenera were traditionally diagnosed by their nesting substrate, social behavior and morphology. However, accumulating evidence suggests that these features are not reliable for their separation, especially with the discovery of an enigmatic species sharing characteristics from both subgenera. Our objective is to provide a phylogenetic hypothesis to evaluate the monophyly of the extant subgenera and to place a new species, Augochlora (Augochlora) intermedia sp. nov. For this purpose, we compiled 110 unordered characters for 40 species of Augochlora plus seven outgroup species and analyzed under parsimony and Bayesian inference. Topologies were very similar under both frameworks, allowing us to consistently characterize a few major lineages. Our results demonstrate that the extant subgenera correspond to monophyletic groups and the new species is sister group to remaining Augochlora s. str. species. Both subgenera are widespread in the Western Hemisphere, with species groups differing in range and distributional patterns. Our interpretation is that Augochlora arose in South America, subsequently colonizing Mesoamerica, the Caribbean and North America several times. Facultative social behavior can be found in both subgenera and in most lineages, indicating that the exclusive solitary behavior found in Augochlora pura is an exception. Based on morphological clues we interpret that the habit of nesting out of the soil arose once in Augochlora s. str.
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Valdés, Catalina, and Magdalena Montalbán. "“… It Was Highly Desirable They Should Be Illustrated”." Nuncius 34, no. 1 (2019): 99–127. http://dx.doi.org/10.1163/18253911-03401004.
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Abstract The purpose of this article is to study the images included in the report made by the U.S. Navy Astronomical Expedition in the Southern Hemisphere between 1849 and 1852, directed by Navy lieutenant and astronomer James Melville Gilliss (1881–1865). Together with astronomical studies, the expedition addressed different aspects of the natural and social history of the Republic of Chile setting down in six volumes a pioneering panoramic vision of the young nation. Considering the different aspects of the culture of printing as it developed in the main cities of the United States in the mid nineteenth century, this article proposes general reflections concerning the impetus given in this field by scientific expeditions. In the specific case of Gilliss’s Naval Astronomical Expedition, this impulse manifests itself in terms of the technological renewal and the prestige of the lithographers taking part in the publication. This contrasts with the subsequent scarce success of Gilliss’s volumes – the books came close to being ignored – both in the United States and in Chile.
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Pirlo, Jeanette. "Broadening Participation in an Increasingly Digitized World." Biodiversity Information Science and Standards 2 (July 4, 2018): e25972. http://dx.doi.org/10.3897/biss.2.25972.
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Participation within digitized collections has shown boom, but diversity of participants has remained static. Traditionally, natural history collections were only utilized by researchers with access to the physical collections. With the advent of open source digitized specimens, whether through transcription of the original label onto an electronic database, sound bites, two-dimensional photographs, or three-dimensional volume files, natural history collections are now at nearly everyone’s fingertips. Although collections have been historically clustered in the northern hemisphere, preliminary data suggest that researchers from the southern hemisphere have started using collections more via online portals. Studies have shown that a more heterogeneous community leads to an increase in the quality of science and publications. iDigBio (Integrated Digitized Biocollections), the United States’ national resource for Advancing Digitization of Biodiversity Collections (ADBC), is a National Science Foundation (NSF) funded initiative that makes millions of biological specimens, in the form of data and images, available electronically to the wider world. Our network of institutions across the world provide the digitized content that makes up our search portal. Minority serving institutions (MSIs) are an important resource for under served communities in the United States. They provide the educational and social skills required to overcome discrimination and economic disparities that these communities often face. Here, we focus on the types of institutions involved in uploading data, specifically those that identify as MSIs and the role they play in the field. After assessing MSI participation with the ADBC program by comparing databases of participants, I found that out of the nearly 400 individual institutions that contribute to the database, one-third of them identify as an MSI. The next step is further engaging contributing MSIs and identifying MSIs with natural history collections that are not a part of the iDigBio network and inviting them to join. By incorporating them into our network, we hope to reach underserved populations of students while broadening the scope of collections available. Including MSIs into our greater community of partners is not enough. We are striving to provide a greater understanding of how the iDigBio portal is used by new communities in the US with limited resources. In this way, we can provide educators with the tools necessary to better prepare their students for Science, Technology, Engineering, and Mathematics (STEM) careers, as well as improving the collections available to the world.
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Pauly, Daniel, Reg Watson, and Jackie Alder. "Global trends in world fisheries: impacts on marine ecosystems and food security." Philosophical Transactions of the Royal Society B: Biological Sciences 360, no. 1453 (2005): 5–12. http://dx.doi.org/10.1098/rstb.2004.1574.
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This contribution, which reviews some broad trends in human history and in the history of fishing, argues that sustainability, however defined, rarely if ever occurred as a result of an explicit policy, but as result of our inability to access a major part of exploited stocks. With the development of industrial fishing, and the resulting invasion of the refuges previously provided by distance and depth, our interactions with fisheries resources have come to resemble the wars of extermination that newly arrived hunters conducted 40 000–50 000 years ago in Australia, and 11 000–13 000 years ago against large terrestrial mammals arrived in North America. These broad trends are documented here through a map of change in fish sizes, which displays characteristic declines, first in the nearshore waters of industrialized countries of the Northern Hemisphere, then spread offshore and to the Southern Hemisphere. This geographical extension met its natural limit in the late 1980s, when the catches from newly accessed stocks ceased to compensate for the collapse in areas accessed earlier, hence leading to a gradual decline of global landing. These trends affect developing countries more than the developed world, which have been able to meet the shortfall by increasing imports from developing countries. These trends, however, together with the rapid growth of farming of carnivorous fishes, which consumes other fishes suited for human consumption, have led to serious food security issues. This promotes urgency to the implementation of the remedies traditionally proposed to alleviate overfishing (reduction of overcapacity, enforcement of conservative total allowable catches, etc.), and to the implementation of non–conventional approaches, notably the re–establishment of the refuges (also known as marine reserves), which made possible the apparent sustainability of pre–industrial fisheries.
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Uścinowicz, Szymon, Małgorzata Witak, Grażyna Miotk-Szpiganowicz, et al. "Climate and sea level variability on a centennial time scale over the last 1500 years as inferred from the Coastal Peatland of Puck Lagoon (southern Baltic Sea)." Holocene 30, no. 12 (2020): 1801–16. http://dx.doi.org/10.1177/0959683620950451.
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The climate variability and related sea-level changes during the Holocene are still under discussion, especially in a regional context. Very little information comes from the southern and south-eastern Baltic coast. The aim of the paper is to gain insight on the history of regional environmental changes, particularly sea-level and storminess, and their driving forces. The investigations were located on a peatland on the coast of Puck Lagoon (Gulf of Gdańsk, southern Baltic Sea). The analysis of peat core comprised: radiocarbon dating, analysis of stable isotopes 18O and 13C and chemical components, as well as palynological and diatomic studies. Results showed the 1.0 m peat section accumulated over 1500 years, with a time resolution of 100 years per sample. The average water level in the Puck Lagoon rose by ca. 0.85 m during the last 1500 years in a cyclic mode, with a period cycle of ca. 600–550 years and an amplitude not exceeding 0.5 m. The accelerated sea level rise and frequent storminess occurred during the first half of the Dark Ages (1500−1300 years b2k) and LIA (750−450 years b2k) and since the beginning of the 20th century. Recognized environmental changes are well correlated with both temperature changes in the North Atlantic and changes in total solar irradiance, suggesting synchronous Northern Hemisphere-wide fluctuations. The solar forcing was an important constituent of natural climate variability in the past and of forcing climate warming during modern times - after the Little Ice Age.
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Carbutt, Clinton, and Dave I. Thompson. "Mountain Watch: How LT(S)ER Is Safeguarding Southern Africa’s People and Biodiversity for a Sustainable Mountain Future." Land 10, no. 10 (2021): 1024. http://dx.doi.org/10.3390/land10101024.
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Southern Africa is an exceptionally diverse region with an ancient geologic and climatic history. Its mountains are located in the Southern Hemisphere mid-latitudes at a tropical–temperate interface, offering a rare opportunity to contextualise and frame our research from an austral perspective to balance the global narrative around sustainable mountain futures for people and biodiversity. Limited Long-Term Ecological Research (LTER) was initiated more than a century ago in South Africa to optimise catchment management through sound water policy. The South African Environmental Observation Network (SAEON) has resurrected many government LTER programmes and added observatories representative of the country’s heterogeneous zonobiomes, including its mountain regions. LTER in other Southern African mountains is largely absent. The current rollout of the Expanded Freshwater and Terrestrial Environmental Observation Network (EFTEON) and the Southern African chapters of international programmes such as the Global Observation Research Initiative in Alpine Environments (GLORIA), RangeX, and the Global Soil Biodiversity Observation Network (Soil BON), as well as the expansion of the Mountain Invasion Research Network (MIREN), is ushering in a renaissance period of global change research in the region, which takes greater cognisance of its social context. This diversity of initiatives will generate a more robust knowledge base from which to draw conclusions about how to better safeguard the well-being of people and biodiversity in the region and help balance livelihoods and environmental sustainability in our complex, third-world socio-ecological mountain systems.
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CONLAN, KATHLEEN E., ANDREA DESIDERATO, and JAN BEERMANN. "Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus." Zootaxa 4939, no. 1 (2021): 1–191. http://dx.doi.org/10.11646/zootaxa.4939.1.1.
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The amphipod genus Jassa Leach, 1814 now comprises 24 species that occur in temperate regions of both hemispheres on solid substrates from the lower intertidal zone to 500 m depth. The propensity for some species to form dense colonies in water intake structures and offshore platforms has brought them to attention as an unwanted pest. Based on the examination of ~25,000 specimens from ~1,100 museum and private collections, it is evident that some species of Jassa have been transported by human vectors since at least the 19th century and now occur widely. Their colonial, tube-living habit enables such transport, and collection records document them on ships, buoys and portable water systems as well as on natural movable substrates such as logs, drift algae and larger crustaceans. Because Jassa can be so readily found, but species discrimination has had a problematic history, the purpose of this monograph is to assist researchers to identify species through illustrations, descriptions, keys and habitat summaries. Seven species which were named in the 19th century but whose names have lapsed are placed in the context of currently known species. Two new species, J. laurieae n. sp. and J. kimi n. sp. are described, and J. monodon (Heller, 1866) and J. valida (Dana, 1853) are resurrected. Jassa mendozai Winfield et al., 2021 is submerged under J. valida, and J. cadetta Krapp et al., 2008 and J. trinacriae Krapp et al., 2010 are submerged under J. slatteryi Conlan, 1990. Morphological differences are related to current understanding of growth, behaviour and ecology. CO1 analysis suggests a Southern Hemisphere origin with diversification northward and an evolutionary direction toward greater physiological plasticity, leading to success in long distance transport and establishment in exotic locations. Correct identification of Jassa world-wide will facilitate further research on this ecologically important genus and will allow for differentiation of indigenous from exotic introductions.
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Fullagar, Kate. "Producing Philosophes in Oceania: Enlightenment through Pacific Spaces." Eighteenth-Century Life 45, no. 3 (2021): 16–33. http://dx.doi.org/10.1215/00982601-9272985.
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The belated European rediscovery of the Pacific helped to test, modify, extend, or otherwise realize the critical, collecting, and conjecturing ethos of the Enlightenment. Whether official philosophers or not, voyagers found in the “new” space of the Pacific more data about the natural and social worlds than they had known before, which led to more empirical comparing, more systematic speculation, and more secular self-questioning. Most scholarship on Enlightenment and Pacific voyaging, however, focuses on relatively elite or well-educated thinkers who were already on the path toward an Enlightenment mindset before they even saw the southern hemisphere. A different story about Enlightenment and the Pacific emerges for less-obviously philosophical voyagers. For these travelers—most of them destined for a maritime but not necessarily an intellectual life—the Pacific could prove to be the primary or originary field for creating an Enlightenment disposition. More particularly, interactions with Pacific people were the means by which some Europeans apprehended what their “philosophical betters” typically discovered via texts. Pacific spaces prompted Enlightenment practices in ordinary mariners more readily or more evidently than they originated them in the educationally advantaged. This article surveys the experiences of a handful of ordinary voyagers to the Pacific Ocean. It aims to move forward discussions about the role the Pacific region and Pacific people played in developing so-called Western modernity.
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Broadfield, Nicholas, and Melinda T. McHenry. "A World of Gorse: Persistence of Ulex europaeus in Managed Landscapes." Plants 8, no. 11 (2019): 523. http://dx.doi.org/10.3390/plants8110523.
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Gorse (Ulex europeus L.) is a woody legume and invasive woody weed that has been introduced to temperate pastoral landscapes worldwide. Despite the apparent cosmopolitan distribution of gorse across much of the temperate agroecological landscapes of the world, research and practice pertaining to the management of gorse has been largely constrained to single-treatments, regions, or timeframes. Gorse eradication has been widely attempted, with limited success. Using the PRISMA (preferred reporting items for systematic reviews and meta-analysis) method and a quasi-metanalytical approach, we reviewed the seminal ~299 papers pertaining to gorse management. We identified (i) the ecological characteristics of the species that predispose gorse to behaving invasively, and (ii) the success of management actions (from a plant ecological life history perspective) in reducing weed vigour and impact. A broad ecological niche, high reproductive output, propagule persistence, and low vulnerability to pests allow for rapid landscape exploitation by gorse throughout much the world. Additionally, there are differences in flowering duration and season in the northern and southern hemisphere that make gorse particularly pernicious in the latter, as gorse flowers twice per year. The implications of these life history stages and resistance to environmental sieves after establishment are that activity and efficacy of control is more likely to be favourable in juvenile stages. Common approaches to gorse control, including herbicides, biological controls, and fire have not been ubiquitously successful, and may in fact target the very site resources—sward cover, soil stability, hydrological balance—that, when degraded, facilitate gorse invasion. Ongoing seedling regeneration presents difficulties if eradication is a goal, but facilitated competition may reduce costs via natural suppression. Mechanical methods of gorse removal, though highly successful, induce chronic soil erosion and land degradation and should hence be used sparingly.
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Xie, Qiulan, Yan Lin, Roger J. Arnold, and Jiangzhong Luo. "How Corymbia citriodora from various origins genetically differ in their environmental adaption in China." Agrociencia Uruguay 27, NE2 (2023): e1289. http://dx.doi.org/10.31285/agro.27.1289.
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Corymbia citriodora subsp. citriodora has a long history of cultivation as a multipurpose tree in China and many other countries of southeast and south Asia. Despite its over 100-year history of introduction outside from Australia, the genetic differences on environmental adaption among and/or within provenances/seed sources when introduced to the other hemisphere are rarely reported. To test and genetically improve this species, a field trial was established in southern China in 2015. In this trial, 5 natural stand seed sources from Australia and 6 seed sources from exotic plantings in China were tested, 171 families in total. Significant variation was found among and within both seed sources and families within these seed sources for pest (cockchafer) and disease (Quambalaria pitereka) resistance, survival, growth and stem form up to age 81 months. Australian seed sources were generally superior for most of the traits to Chinese ones. There was also significant difference among sources within each country. In the Australian sources, sources 2 (Glen Gorden) and 5 (NE Mareeba) were significantly better than the other Australian seed sources. But source 4 (Hughenden) was notably inferior to all other Australian sources. Survival rate of the three sources at 81 months were 55.1%, 50.7% and 26.1%. It is noteworthy that source 4 was from a further southern location in Australia, while the four other Australian sources were from far north in North Queensland. Significant differences were also found among the Chinese seed sources for these traits, with source 8 (Huizhou) and source 10 (Dongmen) being significantly better than the other Chinese sources on most traits, and with a survival rate of 31.6% and 28.0%. The individual tree heritability for the assessed traits was low to moderate ranging from 0.11±0.24 for an index of tree crown health at age 31 months up to 0.48±0.60 for disease resistance at age 10 months. Phenotypic and genetic correlations (rg) among traits were generally favourable, age 10-month Disease susceptibility and age 81-month tree volume (rg= 0.53±0.32), and age 31-month tree volume and age 81-month tree volume (rg= 0.96±0.49). Overall, the genetic variation observed in the field trial along with the heritability and genetic correlation indicate good potential for reasonable genetic gains in this species from selection and ongoing breeding.
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Wilf, Peter, Scott L. Wing, Herbert W. Meyer, et al. "An image dataset of cleared, x-rayed, and fossil leaves vetted to plant family for human and machine learning." PhytoKeys 187 (December 16, 2021): 93–128. http://dx.doi.org/10.3897/phytokeys.187.72350.
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Leaves are the most abundant and visible plant organ, both in the modern world and the fossil record. Identifying foliage to the correct plant family based on leaf architecture is a fundamental botanical skill that is also critical for isolated fossil leaves, which often, especially in the Cenozoic, represent extinct genera and species from extant families. Resources focused on leaf identification are remarkably scarce; however, the situation has improved due to the recent proliferation of digitized herbarium material, live-plant identification applications, and online collections of cleared and fossil leaf images. Nevertheless, the need remains for a specialized image dataset for comparative leaf architecture. We address this gap by assembling an open-access database of 30,252 images of vouchered leaf specimens vetted to family level, primarily of angiosperms, including 26,176 images of cleared and x-rayed leaves representing 354 families and 4,076 of fossil leaves from 48 families. The images maintain original resolution, have user-friendly filenames, and are vetted using APG and modern paleobotanical standards. The cleared and x-rayed leaves include the Jack A. Wolfe and Leo J. Hickey contributions to the National Cleared Leaf Collection and a collection of high-resolution scanned x-ray negatives, housed in the Division of Paleobotany, Department of Paleobiology, Smithsonian National Museum of Natural History, Washington D.C.; and the Daniel I. Axelrod Cleared Leaf Collection, housed at the University of California Museum of Paleontology, Berkeley. The fossil images include a sampling of Late Cretaceous to Eocene paleobotanical sites from the Western Hemisphere held at numerous institutions, especially from Florissant Fossil Beds National Monument (late Eocene, Colorado), as well as several other localities from the Late Cretaceous to Eocene of the Western USA and the early Paleogene of Colombia and southern Argentina. The dataset facilitates new research and education opportunities in paleobotany, comparative leaf architecture, systematics, and machine learning.
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McTaggart-Cowan, Ron, Lance F. Bosart, John R. Gyakum, and Eyad H. Atallah. "Hurricane Katrina (2005). Part I: Complex Life Cycle of an Intense Tropical Cyclone." Monthly Weather Review 135, no. 12 (2007): 3905–26. http://dx.doi.org/10.1175/2007mwr1875.1.
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Abstract The devastating effects of Hurricane Katrina (2005) on the Gulf Coast of the United States are without compare for natural disasters in recent times in North America. With over 1800 dead and insured losses near $40 billion (U.S. dollars), Katrina ranks as the costliest and one of the deadliest Atlantic hurricanes in history. This study documents the complex life cycle of Katrina, a storm that was initiated by a tropical transition event in the Bahamas. Katrina intensified to a category-1 hurricane shortly before striking Miami, Florida; however, little weakening was observed as the system crossed the Florida peninsula. An analog climatology is used to show that this behavior is consistent with the historical record for storms crossing the southern extremity of the peninsula. Over the warm Gulf of Mexico waters, Katrina underwent two periods of rapid intensification associated with a warm core ring shed by the Loop Current. Between these spinup stages, the storm doubled in size, leading to a monotonic increase in power dissipation until Katrina reached a superintense state on 28 September. A pair of extremely destructive landfalls in Louisiana followed the weakening of the system over shelf waters. Despite its strength as a hurricane, Katrina did not reintensify following extratropical transition. The evolution of the storm’s outflow anticyclone, however, led to a perturbation of the midlatitude flow that is shown in a companion study to influence the Northern Hemisphere over a period of 2 weeks. An understanding of the varied components of Katrina’s complex evolution is necessary for further developing analysis and forecasting techniques as they apply to storms that form near the North American continent and rapidly intensify over the Gulf of Mexico. Given the observed overall increase in Atlantic hurricane activity since the mid-1990s, an enhanced appreciation for the forcings involved in such events could help to mitigate the impact of similar severe hurricanes in the future.
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Allmon, Warren D., Roger Portell, Gary Rosenberg, and Kevin Schindler. "Species diversity of Pliocene-Recent mollusk faunas of the western Atlantic: implications for climatic history." Paleontological Society Special Publications 6 (1992): 4. http://dx.doi.org/10.1017/s2475262200005645.
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The late Cenozoic history of mollusks in the tropical and subtropical Western Atlantic has traditionally been viewed as one of decreasing species richness via a series of more or less discrete extinction episodes, from a Mio-Pliocene peak to the depauperate (relative to the Eastern Pacific) fauna of today. These extinction episodes have been interpreted by some authors as responses to climatic deterioration, especially climatic cooling associated with northern hemisphere glaciation.Two new species-level compilations of gastropods suggest, however, that this traditional scenario may be oversimplified.1) A new (but still preliminary) compilation of species from the Late Pliocene “Pinecrest Sand” of southern Florida contains 365 species. This compilation is based mainly on specimens > 5mm in size taken from bulk samples collected in quarries near Sarasota and held in the collections of the Florida Museum of Natural History; when smaller specimens are considered, and systematic analysis of larger forms from this and other localities is complete, it is likely that this number will increase significantly. The Pinecrest has been systematically neglected; although our count is preliminary, it represents the most complete and well-documented compilation available for this spectacular and highly diverse fauna.This number for the Pinecrest compares with 479 species of gastropods in the overlying Late Pliocene-Early Pleistocene Caloosahatchee “Formation” (data of Campbell et al., 1975). 178 gastropod species are in common between the two units, yielding an extinction level of 51.2%. 301 (62.8%) of the Caloosahatchee gastropod species are not present in the Pinecrest.Stanley (1986) listed 211 species of bivalves in the Pinecrest and 150 in the Calooshatchee, with 110 in common, giving an extinction level of 47.9%. 40 (26.7%) of the Caloosahatchee bivalve species are not present in the Pinecrest.2) A new compilation of all described Recent shelled gastropods in the Western Atlantic (Cape Hatteras to Rio de Janeiro) contains 2800 species (2418 of which were described before 1972), compared to the 2360 species listed by Keen (1971) for the Recent Eastern Pacific. These two lists compare similar size and depth ranges, and indicate that the Western Atlantic gastropod fauna is not less species-rich than the Eastern Pacific gastropod fauna.In addition, a growing body of evidence from other studies (ostracodes, foraminifera, isotopic analyses) indicates that the Late Pliocene was not a time of marked climatic cooling, at least not in the Western Atlantic. Still other studies (e.g., of the biogeography of turritelline gastropods, isotopic analyses on both sides of the Central American Isthmus, paleoceanographic modelling) suggest that the most significant environmental changes at this time may have been associated with changes in nutrient levels.Taken together, these very preliminary results suggest a more complex history for the Western Atlantic mollusk fauna than previously envisioned. If the Plio-Pleistocene was a time of significant turnover but not significant diversity decline, and gastropods of the Recent Western Atlantic are not less diverse than their Eastern Pacific counterparts, then the patterns to be explained must be reexamined. Late Cenozoic extinction may have been significant in the Western Atlantic, but it may have been accompanied by high levels of diversification.In any case, those faunal changes that did occur at this time may have been caused as much or more by changes in nutrient levels as in temperature.
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Orchiston, Wayne. "Book Review: Southern Hemisphere Astronomy, under Capricorn: A History of Southern Hemisphere Astronomy." Journal for the History of Astronomy 21, no. 3 (1990): 304–6. http://dx.doi.org/10.1177/002182869002100311.
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Betty, Emma L., Karen A. Stockin, Adam N. H. Smith, Barbara Bollard, Mark B. Orams, and Sinéad Murphy. "Sexual maturation in male long-finned pilot whales (Globicephala melas edwardii): defining indicators of sexual maturity." Journal of Mammalogy 100, no. 4 (2019): 1387–402. http://dx.doi.org/10.1093/jmammal/gyz086.
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Abstract Male reproductive biology is described for the Southern Hemisphere long-finned pilot whale (Globicephala melas edwardii), a subspecies that regularly mass strands along the New Zealand coastline. Ten mass stranding events sampled over a 7-year period enabled assessments of key life history parameters. Sexual maturation in immature, maturing, and mature males was assessed using morphological data and histological examination of testicular tissue. Variation was observed in the age (11–15 years) and length (450–490 cm) at which individuals attained sexual maturity. Using Bayesian cumulative logit regression models, we estimated the average age and length at the attainment of sexual maturity to be 13.5 years and 472 cm, respectively. Combined testes weight, combined testes length, an index of testicular development (combined testes weight/combined testes length), and mean seminiferous tubule diameter were all good indicators of sexual maturity status. Combined testes length was the best nonhistological indicator, and all testicular measures were found to be better indicators of sexual maturation for G. m. edwardii than age or total body length. Sexual maturity was attained before physical maturity (> 40 years and 570 cm), and at a younger age and smaller body length than previously reported for Globicephala melas melas in the North Atlantic. Given the ease of collection, minimal processing, and applicability to suboptimal material collected from stranding events, future studies should assess the value of testicular size as an indicator of sexual maturity in pilot whales and other cetacean species. Estimates of the average age and length at sexual maturity for G. m. edwardii provided in this study may be used to inform population models required for conservation management of the subspecies, which is subject to high levels of stranding-related mortality.
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Boyer, Tim, Ellen Bartow-Gillies, A. Abida, et al. "Introduction." Bulletin of the American Meteorological Society 104, no. 9 (2023): S1—S10. http://dx.doi.org/10.1175/2023bamsstateoftheclimate_intro.1.
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Abstract —J. BLUNDEN, T. BOYER, AND E. BARTOW-GILLIES Earth’s global climate system is vast, complex, and intricately interrelated. Many areas are influenced by global-scale phenomena, including the “triple dip” La Niña conditions that prevailed in the eastern Pacific Ocean nearly continuously from mid-2020 through all of 2022; by regional phenomena such as the positive winter and summer North Atlantic Oscillation that impacted weather in parts the Northern Hemisphere and the negative Indian Ocean dipole that impacted weather in parts of the Southern Hemisphere; and by more localized systems such as high-pressure heat domes that caused extreme heat in different areas of the world. Underlying all these natural short-term variabilities are long-term climate trends due to continuous increases since the beginning of the Industrial Revolution in the atmospheric concentrations of Earth’s major greenhouse gases. In 2022, the annual global average carbon dioxide concentration in the atmosphere rose to 417.1±0.1 ppm, which is 50% greater than the pre-industrial level. Global mean tropospheric methane abundance was 165% higher than its pre-industrial level, and nitrous oxide was 24% higher. All three gases set new record-high atmospheric concentration levels in 2022. Sea-surface temperature patterns in the tropical Pacific characteristic of La Niña and attendant atmospheric patterns tend to mitigate atmospheric heat gain at the global scale, but the annual global surface temperature across land and oceans was still among the six highest in records dating as far back as the mid-1800s. It was the warmest La Niña year on record. Many areas observed record or near-record heat. Europe as a whole observed its second-warmest year on record, with sixteen individual countries observing record warmth at the national scale. Records were shattered across the continent during the summer months as heatwaves plagued the region. On 18 July, 104 stations in France broke their all-time records. One day later, England recorded a temperature of 40°C for the first time ever. China experienced its second-warmest year and warmest summer on record. In the Southern Hemisphere, the average temperature across New Zealand reached a record high for the second year in a row. While Australia’s annual temperature was slightly below the 1991–2020 average, Onslow Airport in Western Australia reached 50.7°C on 13 January, equaling Australia's highest temperature on record. While fewer in number and locations than record-high temperatures, record cold was also observed during the year. Southern Africa had its coldest August on record, with minimum temperatures as much as 5°C below normal over Angola, western Zambia, and northern Namibia. Cold outbreaks in the first half of December led to many record-low daily minimum temperature records in eastern Australia. The effects of rising temperatures and extreme heat were apparent across the Northern Hemisphere, where snow-cover extent by June 2022 was the third smallest in the 56-year record, and the seasonal duration of lake ice cover was the fourth shortest since 1980. More frequent and intense heatwaves contributed to the second-greatest average mass balance loss for Alpine glaciers around the world since the start of the record in 1970. Glaciers in the Swiss Alps lost a record 6% of their volume. In South America, the combination of drought and heat left many central Andean glaciers snow free by mid-summer in early 2022; glacial ice has a much lower albedo than snow, leading to accelerated heating of the glacier. Across the global cryosphere, permafrost temperatures continued to reach record highs at many high-latitude and mountain locations. In the high northern latitudes, the annual surface-air temperature across the Arctic was the fifth highest in the 123-year record. The seasonal Arctic minimum sea-ice extent, typically reached in September, was the 11th-smallest in the 43-year record; however, the amount of multiyear ice—ice that survives at least one summer melt season—remaining in the Arctic continued to decline. Since 2012, the Arctic has been nearly devoid of ice more than four years old. In Antarctica, an unusually large amount of snow and ice fell over the continent in 2022 due to several landfalling atmospheric rivers, which contributed to the highest annual surface mass balance, 15% to 16% above the 1991–2020 normal, since the start of two reanalyses records dating to 1980. It was the second-warmest year on record for all five of the long-term staffed weather stations on the Antarctic Peninsula. In East Antarctica, a heatwave event led to a new all-time record-high temperature of −9.4°C—44°C above the March average—on 18 March at Dome C. This was followed by the collapse of the critically unstable Conger Ice Shelf. More than 100 daily low sea-ice extent and sea-ice area records were set in 2022, including two new all-time annual record lows in net sea-ice extent and area in February. Across the world’s oceans, global mean sea level was record high for the 11th consecutive year, reaching 101.2 mm above the 1993 average when satellite altimetry measurements began, an increase of 3.3±0.7 over 2021. Globally-averaged ocean heat content was also record high in 2022, while the global sea-surface temperature was the sixth highest on record, equal with 2018. Approximately 58% of the ocean surface experienced at least one marine heatwave in 2022. In the Bay of Plenty, New Zealand’s longest continuous marine heatwave was recorded. A total of 85 named tropical storms were observed during the Northern and Southern Hemisphere storm seasons, close to the 1991–2020 average of 87. There were three Category 5 tropical cyclones across the globe—two in the western North Pacific and one in the North Atlantic. This was the fewest Category 5 storms globally since 2017. Globally, the accumulated cyclone energy was the lowest since reliable records began in 1981. Regardless, some storms caused massive damage. In the North Atlantic, Hurricane Fiona became the most intense and most destructive tropical or post-tropical cyclone in Atlantic Canada’s history, while major Hurricane Ian killed more than 100 people and became the third costliest disaster in the United States, causing damage estimated at $113 billion U.S. dollars. In the South Indian Ocean, Tropical Cyclone Batsirai dropped 2044 mm of rain at Commerson Crater in Réunion. The storm also impacted Madagascar, where 121 fatalities were reported. As is typical, some areas around the world were notably dry in 2022 and some were notably wet. In August, record high areas of land across the globe (6.2%) were experiencing extreme drought. Overall, 29% of land experienced moderate or worse categories of drought during the year. The largest drought footprint in the contiguous United States since 2012 (63%) was observed in late October. The record-breaking megadrought of central Chile continued in its 13th consecutive year, and 80-year record-low river levels in northern Argentina and Paraguay disrupted fluvial transport. In China, the Yangtze River reached record-low values. Much of equatorial eastern Africa had five consecutive below-normal rainy seasons by the end of 2022, with some areas receiving record-low precipitation totals for the year. This ongoing 2.5-year drought is the most extensive and persistent drought event in decades, and led to crop failure, millions of livestock deaths, water scarcity, and inflated prices for staple food items. In South Asia, Pakistan received around three times its normal volume of monsoon precipitation in August, with some regions receiving up to eight times their expected monthly totals. Resulting floods affected over 30 million people, caused over 1700 fatalities, led to major crop and property losses, and was recorded as one of the world’s costliest natural disasters of all time. Near Rio de Janeiro, Brazil, Petrópolis received 530 mm in 24 hours on 15 February, about 2.5 times the monthly February average, leading to the worst disaster in the city since 1931 with over 230 fatalities. On 14–15 January, the Hunga Tonga-Hunga Ha'apai submarine volcano in the South Pacific erupted multiple times. The injection of water into the atmosphere was unprecedented in both magnitude—far exceeding any previous values in the 17-year satellite record—and altitude as it penetrated into the mesosphere. The amount of water injected into the stratosphere is estimated to be 146±5 Terragrams, or ∼10% of the total amount in the stratosphere. It may take several years for the water plume to dissipate, and it is currently unknown whether this eruption will have any long-term climate effect.
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Семенютина, А. В., and М. В. Цой. "Ecological and biological features of taxa of the Cupressaceae family in dendrological collections of the dry-steppe region." World Ecology Journal, no. 2 (October 30, 2021): 4–34. http://dx.doi.org/10.25726/q2423-4851-2863-i.
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Актуальность связана с расширением зеленого строительства на новых территориях в разнообразных и нередко тяжелых природных и агротехнических условиях возникла потребность в широком и разнообразном по биологическим и техническим свойствам ассортименте древесных пород и разработке дифференцированных методов их выращивания. Интродукция должна быть основана на обстоятельном изучении существующего опыта интродукции и знании стран – источников интродукции, истории формирования того или иного вида, учета экологических особенностей местообитаний, вертикальной зональности, существования географических и эдафических форм. Цель исследования заключалась в изучении эколого-биологических особенностей таксонов семейства Cupressaceae Bartl. в дендрологических коллекциях сухостепного региона. Исследованы шесть древесных вида семейства Cupressaceae, произрастающие в дендроколлекциях ФНЦ Агроэкологии РАН: Juniperus virginiana L., J. communis L., J. sabina L., Thuja occidentalis L, Platycladus orientalis(L.) Franco, Pseudotsuga menziesii (Milb) Franco. Изучены естественные ареалы объектов исследования. Выявлено, что виды подсемейства Thujoideae встречаются как в северном, так и в южном полушарии, виды подсемейства Juniperoideae (род Juniperus) – в умеренных областях северного полушария. Фенологические наблюдения выявили, что рост хвои у можжевельника обыкновенного начинался одновременно с ростом побегов в конце марта - начале апреля (на 1-1,5 месяца раньше, чем на родине), Период роста хвои продолжался 2-2,5 месяца, побегов – 135-180 дней. В ходе наблюдений за динамикой роста сеянцев, были получены метрические показатели сеянцев, 1-летние сеянцы Platycladus orientalis – 16-18 см, Thuja occidentalis – 9-14 см, J. communis – 10-15 см, J. sabina – 14-16 см, Juniperus virginiana – 14-16 см высотой. Анализ изменчивости морфологических признаков и биоэкологических свойств, адаптаций в новых условиях среды имеют большое значение для биоэкологического обоснования введения в культуру древесных таксонов семейства Cupressaceae. Этот анализ затрагивает оценку природного разнообразия растений с таких важных сторон, как скорость роста, устойчивость и декоративность, сведений о которых в засушливых условиях крайне мало. The urgency is connected with the expansion of green construction in new territories in diverse and often difficult natural and agrotechnical conditions, there is a need for a wide and diverse assortment of tree species in terms of biological and technical properties and the development of differentiated methods of their cultivation. The introduction should be based on a thorough study of the existing experience of introduction and knowledge of the countries - sources of introduction, the history of the formation of a particular species, taking into account the ecological features of habitats, vertical zonality, the existence of geographical and edaphic forms. The aim of the study was to study the ecological and biological features of the taxa of the Cupressaceae Bartl family. in dendrological collections of the dry-steppe region. Six woody species of the Cupressaceae family growing in the arboretum collections of the Federal Research Center of Agroecology of the Russian Academy of Sciences were studied: Juniperus virginiana L., J. communis L., J. sabina L., Thuja occidentalis L, Platycladus orientalis (L.) Franco, Pseudotsuga menziesii (Milb) Franco. The natural areas of the objects of study have been studied. It was revealed that the species of the subfamily Thujoideae are found in both the northern and southern hemispheres, the species of the subfamily Juniperoideae (genus Juniperus) – in the temperate regions of the northern hemisphere. Phenological observations revealed that the growth of needles in common juniper began simultaneously with the growth of shoots in late March - early April (1-1.5 months earlier than at home), the period of growth of needles lasted 2-2.5 months, shoots - 135-180 days. During observations of the growth dynamics of seedlings, metric indicators of seedlings were obtained, 1-year-old seedlings Platycladus orientalis - 16-18 cm, Thuja occidentalis - 9-14 cm, J. communis - 10-15 cm, J. sabina - 14-16 cm, Juniperus virginiana - 14-16 cm tall. Analysis of the variability of morphological features and bioecological properties, adaptations in new environmental conditions are of great importance for the bioecological justification of the introduction of woody taxa of the Cupressaceae family into culture. This analysis affects the assessment of the natural diversity of plants from such important aspects as growth rate, stability and decorative properties, information about which is extremely scarce in arid conditions.
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Thomas, Jordan L., Darryn W. Waugh, and Anand Gnanadesikan. "Southern Hemisphere extratropical circulation: Recent trends and natural variability." Geophysical Research Letters 42, no. 13 (2015): 5508–15. http://dx.doi.org/10.1002/2015gl064521.
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Mayewski, P. A., and K. A. Maasch. "Recent warming inconsistent with natural association between temperature and atmospheric circulation over the last 2000 years." Climate of the Past Discussions 2, no. 3 (2006): 327–55. http://dx.doi.org/10.5194/cpd-2-327-2006.
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Abstract. Comparison between proxies for atmospheric circulation and temperature reveals associations over the last few decades that are inconsistent with those of the past 2000 years. Notably, patterns of middle to high latitude atmospheric circulation in both hemispheres are still within the range of variability of the last 6–10 centuries while, as demonstrated by Mann and Jones (2003), Northern Hemisphere temperatures over recent decades are the highest of the last 2000 years. Further, recent temperature change precedes change in middle to high latitude atmospheric circulation unlike the two most notable changes in climate of the past 2000 years during which change in atmospheric circulation preceded or coincided with change in temperature. In addition, the most prominent change in Southern Hemisphere temperature and atmospheric circulation of the past 2000, and probably 9000 years, precedes change in temperature and atmospheric circulation in the Northern Hemisphere unlike the recent change in Northern Hemisphere temperature that leads. These findings provide new verification that recent rise in temperature is inconsistent with natural climate variability and is most likely related to anthropogenic activity in the form of enhanced greenhouse gases. From our investigation we conclude that the delayed warming over much of the Southern Hemisphere may be, in addition to other factors, a consequence of underpinning by natural climate variability. Further bipolar comparison of proxy records of atmospheric circulation demonstrates that change in atmospheric circulation in the Southern Hemisphere led by 400 years, the most abrupt change in Northern Hemisphere atmospheric circulation of the last 9000 years. This finding may be highly relevant to understanding a future when warming becomes more fully established in the Southern Hemisphere.
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Leão, Pedro, Lia C. R. S. Teixeira, Jefferson Cypriano, et al. "North-Seeking Magnetotactic Gammaproteobacteria in the Southern Hemisphere." Applied and Environmental Microbiology 82, no. 18 (2016): 5595–602. http://dx.doi.org/10.1128/aem.01545-16.
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ABSTRACTMagnetotactic bacteria (MTB) comprise a phylogenetically diverse group of prokaryotes capable of orienting and navigating along magnetic field lines. Under oxic conditions, MTB in natural environments in the Northern Hemisphere generally display north-seeking (NS) polarity, swimming parallel to the Earth's magnetic field lines, while those in the Southern Hemisphere generally swim antiparallel to magnetic field lines (south-seeking [SS] polarity). Here, we report a population of an uncultured, monotrichously flagellated, and vibrioid MTB collected from a brackish lagoon in Brazil in the Southern Hemisphere that consistently exhibits NS polarity. Cells of this organism were mainly located below the oxic-anoxic interface (OAI), suggesting it is capable of some type of anaerobic metabolism. Magnetosome crystalline habit and composition were consistent with elongated prismatic magnetite (Fe3O4) particles. Phylogenetic analysis based on 16S rRNA gene sequencing indicated that this organism belongs to a distinct clade of theGammaproteobacteriaclass. The presence of NS MTB in the Southern Hemisphere and the previously reported finding of SS MTB in the Northern Hemisphere reinforce the idea that magnetotaxis is more complex than we currently understand and may be modulated by factors other than O2concentration and redox gradients in sediments and water columns.IMPORTANCEMagnetotaxis is a navigational mechanism used by magnetotactic bacteria to move along geomagnetic field lines and find an optimal position in chemically stratified sediments. For that, magnetotactic bacteria swim parallel to the geomagnetic field lines under oxic conditions in the Northern Hemisphere, whereas those in the Southern Hemisphere swim antiparallel to magnetic field lines. A population of uncultured vibrioid magnetotactic bacteria was discovered in a brackish lagoon in the Southern Hemisphere that consistently swim northward, i.e., the opposite of the overwhelming majority of other Southern Hemisphere magnetotactic bacteria. This finding supports the idea that magnetotaxis is more complex than previously thought.
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Wolfe, Jack A. "Late Cretaceous-Cenozoic history of deciduousness and the terminal Cretaceous event." Paleobiology 13, no. 2 (1987): 215–26. http://dx.doi.org/10.1017/s0094837300008769.
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Deciduousness in mesic, broad-leaved plants occurred in disturbed, middle-latitude environments during the Late Cretaceous. Only in polar environments in the Late Cretaceous was the deciduous element dominant, although of low diversity. The terminal Cretaceous event resulted in wide-spread selection for plants of deciduous habit and diversification of deciduous taxa, thus leaving a lasting imprint on Northern Hemisphere vegetation. Various environmental factors have played important roles in subsequent diversification of mesic, broad-leaved deciduous taxa and in origination and decline of broad-leaved deciduous forests. Low diversity and rarity of mesic deciduous plants in the post-Cretaceous of the Southern Hemisphere indicate that the inferred “impact winter” of the terminal Cretaceous event had little effect on Southern Hemisphere vegetation and climate.
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Beck, Jonas, Michael Bock, Jochen Schmitt, Barbara Seth, Thomas Blunier, and Hubertus Fischer. "Bipolar carbon and hydrogen isotope constraints on the Holocene methane budget." Biogeosciences 15, no. 23 (2018): 7155–75. http://dx.doi.org/10.5194/bg-15-7155-2018.
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Abstract. Atmospheric methane concentration shows a well-known decrease over the first half of the Holocene following the Northern Hemisphere summer insolation before it started to increase again to preindustrial values. There is a debate about what caused this change in the methane concentration evolution, in particular, whether an early anthropogenic influence or natural emissions led to the reversal of the atmospheric CH4 concentration evolution. Here, we present new methane concentration and stable hydrogen and carbon isotope data measured on ice core samples from both Greenland and Antarctica over the Holocene. With the help of a two-box model and the full suite of CH4 parameters, the new data allow us to quantify the total methane emissions in the Northern Hemisphere and Southern Hemisphere separately as well as their stable isotopic signatures, while interpretation of isotopic records of only one hemisphere may lead to erroneous conclusions. For the first half of the Holocene our results indicate an asynchronous decrease in Northern Hemisphere and Southern Hemisphere CH4 emissions by more than 30 Tg CH4 yr−1 in total, accompanied by a drop in the northern carbon isotopic source signature of about −3 ‰. This cannot be explained by a change in the source mix alone but requires shifts in the isotopic signature of the sources themselves caused by changes in the precursor material for the methane production. In the second half of the Holocene, global CH4 emissions increased by about 30 Tg CH4 yr−1, while preindustrial isotopic emission signatures remained more or less constant. However, our results show that this early increase in methane emissions took place in the Southern Hemisphere, while Northern Hemisphere emissions started to increase only about 2000 years ago. Accordingly, natural emissions in the southern tropics appear to be the main cause of the CH4 increase starting 5000 years before present, not supporting an early anthropogenic influence on the global methane budget by East Asian land use changes.
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Cole-Dai, Jihong, Ellen Mosley-Thompson, and Lonnie G. Thompson. "Annually resolved southern hemisphere volcanic history from two Antarctic ice cores." Journal of Geophysical Research: Atmospheres 102, no. D14 (1997): 16761–71. http://dx.doi.org/10.1029/97jd01394.
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Rule, James P., Justin W. Adams, Felix G. Marx, et al. "First monk seal from the Southern Hemisphere rewrites the evolutionary history of true seals." Proceedings of the Royal Society B: Biological Sciences 287, no. 1938 (2020): 20202318. http://dx.doi.org/10.1098/rspb.2020.2318.
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Living true seals (phocids) are the most widely dispersed semi-aquatic marine mammals, and comprise geographically separate northern (phocine) and southern (monachine) groups. Both are thought to have evolved in the North Atlantic, with only two monachine lineages—elephant seals and lobodontins—subsequently crossing the equator. The third and most basal monachine tribe, the monk seals, have hitherto been interpreted as exclusively northern and (sub)tropical throughout their entire history. Here, we describe a new species of extinct monk seal from the Pliocene of New Zealand, the first of its kind from the Southern Hemisphere, based on one of the best-preserved and richest samples of seal fossils worldwide. This unanticipated discovery reveals that all three monachine tribes once coexisted south of the equator, and forces a profound revision of their evolutionary history: rather than primarily diversifying in the North Atlantic, monachines largely evolved in the Southern Hemisphere, and from this southern cradle later reinvaded the north. Our results suggest that true seals crossed the equator over eight times in their history. Overall, they more than double the age of the north–south dichotomy characterizing living true seals and confirms a surprisingly recent major change in southern phocid diversity.
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Kühn, Susanne, Albert van Oyen, Elisa L. Bravo Rebolledo, Amalie V. Ask, and Jan Andries van Franeker. "Polymer types ingested by northern fulmars (Fulmarus glacialis) and southern hemisphere relatives." Environmental Science and Pollution Research 28, no. 2 (2020): 1643–55. http://dx.doi.org/10.1007/s11356-020-10540-6.
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AbstractAlthough ingestion of plastic by tubenosed seabirds has been documented regularly, identification of the polymer composition of these plastics has rarely been described. Polymer assessment may assist in identifying sources and may indicate risks from additives occurring in specific types of polymers. Using known test materials, two identification methods Fourier transform infrared spectroscopy and near infrared spectroscopy (FTIR and NIR) were compared. Although both methods were found to be similarly suitable for identification of plastic polymers, a significant difference was observed in identification of natural materials. FTIR frequently misclassified natural materials as being a synthetic polymer. Within our results, an 80% match score threshold functioned best to distinguish between natural items and synthetics. Using NIR, the historical variability of plastics ingested by northern fulmars (Fulmarus glacialis) from the Dutch sector of the North Sea was analysed for three time periods since the 1980s. For the more recent decade, variability between fulmars from different regions in the northeast Atlantic was investigated. Regional variation was further explored by analysing plastics obtained from the stomachs of southern hemisphere relatives of the fulmar (southern fulmar, cape petrel, snow petrel) and Wilson’s storm petrel. Results show that proportional abundance of polymer types in these seabirds is closely related to the plastic categories that they ingest (e.g. pellets, foam, fragments). The uptake of different plastic categories and related polymer types most likely reflects spatial and temporal variations in availability rather than ingestion preferences of the birds.
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Parrish, David D., Richard G. Derwent, Steven T. Turnock, et al. "Investigations on the anthropogenic reversal of the natural ozone gradient between northern and southern midlatitudes." Atmospheric Chemistry and Physics 21, no. 12 (2021): 9669–79. http://dx.doi.org/10.5194/acp-21-9669-2021.
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Abstract. Our quantitative understanding of natural tropospheric ozone concentrations is limited by the paucity of reliable measurements before the 1980s. We utilize the existing measurements to compare the long-term ozone changes that occurred within the marine boundary layer at northern and southern midlatitudes. Since 1950 ozone concentrations have increased by a factor of 2.1 ± 0.2 in the Northern Hemisphere (NH) and are presently larger than in the Southern Hemisphere (SH), where only a much smaller increase has occurred. These changes are attributed to increased ozone production driven by anthropogenic emissions of photochemical ozone precursors that increased with industrial development. The greater ozone concentrations and increases in the NH are consistent with the predominant location of anthropogenic emission sources in that hemisphere. The available measurements indicate that this interhemispheric gradient was much smaller and was likely reversed in the pre-industrial troposphere with higher concentrations in the SH. Six Earth system model (ESM) simulations indicate similar total NH increases (1.9 with a standard deviation of 0.3), but they occurred more slowly over a longer time period, and the ESMs do not find higher pre-industrial ozone in the SH. Several uncertainties in the ESMs may cause these model–measurement disagreements: the assumed natural nitrogen oxide emissions may be too large, the relatively greater fraction of ozone injected by stratosphere–troposphere exchange to the NH may be overestimated, ozone surface deposition to ocean and land surfaces may not be accurately simulated, and model treatment of emissions of biogenic hydrocarbons and their photochemistry may not be adequate.
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Canales-Aguirre, Cristian B., Peter A. Ritchie, Sebastián Hernández, et al. "Phylogenetic relationships, origin and historical biogeography of the genus Sprattus (Clupeiformes: Clupeidae)." PeerJ 9 (August 18, 2021): e11737. http://dx.doi.org/10.7717/peerj.11737.
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The genus Sprattus comprises five species of marine pelagic fishes distributed worldwide in antitropical, temperate waters. Their distribution suggests an ancient origin during a cold period of the earth’s history. In this study, we evaluated this hypothesis and corroborated the non-monophyly of the genus Sprattus, using a phylogenetic approach based on DNA sequences of five mitochondrial genome regions. Sprattus sprattus is more closely related to members of the genus Clupea than to other Sprattus species. We also investigated the historical biogeography of the genus, with the phylogenetic tree showing two well-supported clades corresponding to the species distribution in each hemisphere. Time-calibrated phylogenetic analyses showed that an ancient divergence between Northern and Southern Hemispheres occurred at 55.8 MYBP, followed by a diversification in the Oligocene epoch in the Northern Hemisphere clade (33.8 MYBP) and a more recent diversification in the Southern Hemisphere clade (34.2 MYBP). Historical biogeography analyses indicated that the most recent common ancestor (MRCA) likely inhabited the Atlantic Ocean in the Southern Hemisphere. These results suggest that the ancestral population of the MRCA diverged in two populations, one was dispersed to the Northern Hemisphere and the other across the Southern Hemisphere. Given that the Eocene was the warmest epoch since the Paleogene, the ancestral populations would have crossed the tropics through deeper cooler waters, as proposed by the isothermal submergence hypothesis. The non-monophyly confirmed for the genus Sprattus indicates that its systematics should be re-evaluated.
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Weller, Evan, Bo-Joung Park, and Seung-Ki Min. "Anthropogenic and Natural Contributions to the Lengthening of the Southern Hemisphere Summer Season." Journal of Climate 33, no. 24 (2020): 10539–53. http://dx.doi.org/10.1175/jcli-d-20-0084.1.
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AbstractThis study provides the first quantitative assessment of observed long-term changes in summer-season timing and length in the Southern Hemisphere (SH) and its subregions over the past 60 years, enabling a global completeness by complementing such characteristics previously reported for the Northern Hemisphere (NH). Using an objective algorithm that is based on temperature indices, relative measures of summer onset, withdrawal, and duration are determined at each land location over the period 1953–2012. Significant widespread summer-season lengthening, due to earlier onset and delayed withdrawal, has occurred across the SH, a longer period for extreme heat-wave events and wildfires to potentially occur. The asymmetric magnitude (onset vs withdrawal) in summer-season lengthening is slightly less over the SH than over the NH. Contributions of anthropogenic and natural factors to the observed trends in summer-season characteristics were investigated using phase 5 of the Coupled Model Intercomparison Project (CMIP5) multimodel simulations integrated with observed external forcings [anthropogenic plus natural (ALL)], greenhouse gas forcing only (GHG), and natural forcing only [solar and volcanic activities (NAT)]. Overall, consistent with the NH, increased greenhouse gases were the main cause of observed changes in the SH, with negligible contribution from other external forcings. ALL and GHG simulations also reproduced a slight tendency for earlier summer onset to contribute more to summer lengthening. Proportions of observed regional trends in summer-season indices attributable to trends in long-term internal variability in the SH, namely, the interdecadal Pacific oscillation (IPO) and southern annular mode (SAM), suggests such variability can only explain up to ~12%, supporting the dominant role of greenhouse gas forcing.
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Woodruff, William, and Donald Denoon. "Settler Capitalism: The Dynamics of Dependent Development in the Southern Hemisphere." American Historical Review 90, no. 1 (1985): 109. http://dx.doi.org/10.2307/1860758.
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Duncanson, Rob, and Walter P. Purio. "Uncharted waters: LNG as a marine fuel in Australasia." APPEA Journal 57, no. 2 (2017): 434. http://dx.doi.org/10.1071/aj16083.
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This paper explores the emerging market for liquefied natural gas (LNG) as a marine fuel, with a particular focus on the market in Australasia. While LNG as a marine fuel is a growing market in the northern hemisphere, slower rates of adoption of LNG fuel technologies in maritime industry are evident in the southern hemisphere. This paper aims to ground the Australasian LNG marine fuel market in a global context and to explore opportunities for Australia to lead the region in developing and adopting LNG as a marine fuel. This paper looks at the key drivers behind championing LNG as a marine fuel, focusing on four main areas of impact; economy, environment, public health and innovation. This paper uses Australia as a case study for the adoption of LNG as a marine fuel in the southern hemisphere. It considers the opportunities presented by LNG as a marine fuel to assist Australia in: achieving energy independence; reducing the impact of air pollution from ships on the environment and public health; and positioning Australia as an innovative leader in LNG as a marine fuel.
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Regayre, Leighton A., Julia Schmale, Jill S. Johnson, et al. "The value of remote marine aerosol measurements for constraining radiative forcing uncertainty." Atmospheric Chemistry and Physics 20, no. 16 (2020): 10063–72. http://dx.doi.org/10.5194/acp-20-10063-2020.
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Abstract. Aerosol measurements over the Southern Ocean are used to constrain aerosol–cloud interaction radiative forcing (RFaci) uncertainty in a global climate model. Forcing uncertainty is quantified using 1 million climate model variants that sample the uncertainty in nearly 30 model parameters. Measurements of cloud condensation nuclei and other aerosol properties from an Antarctic circumnavigation expedition strongly constrain natural aerosol emissions: default sea spray emissions need to be increased by around a factor of 3 to be consistent with measurements. Forcing uncertainty is reduced by around 7 % using this set of several hundred measurements, which is comparable to the 8 % reduction achieved using a diverse and extensive set of over 9000 predominantly Northern Hemisphere measurements. When Southern Ocean and Northern Hemisphere measurements are combined, uncertainty in RFaci is reduced by 21 %, and the strongest 20 % of forcing values are ruled out as implausible. In this combined constraint, observationally plausible RFaci is around 0.17 W m−2 weaker (less negative) with 95 % credible values ranging from −2.51 to −1.17 W m−2 (standard deviation of −2.18 to −1.46 W m−2). The Southern Ocean and Northern Hemisphere measurement datasets are complementary because they constrain different processes. These results highlight the value of remote marine aerosol measurements.
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Bashford, Alison, Pratik Chakrabarti, and Jarrod Hore. "Towards a modern history of Gondwanaland." Journal of the British Academy 9s6 (2021): 5–26. http://dx.doi.org/10.5871/jba/009s6.005.
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Gondwanaland was a southern mega-continent that began to break up 180 million years ago. This article explores Gondwanaland�s modern history, its unexpected political and cultural purchase since the 1880s. Originating with geological and palaeontological research in the Gond region of Central India, �Gondwana� has become recognisable and useful, especially in settler colonial contexts. This prospectus sets out a program for a highly unusual �transnational� project, involving scholars of India, Australia, Antarctica, southern Africa and South America. Unpredictably across the five continents of former Gondwanaland, the term itself signals depth of time and place across the spectrum of Indigenous land politics, coal-based extractive politics, and, paradoxically, nationalist environmental politics. All kinds of once-living Gondwanaland biota deliver us fossil fuels today � the �gifts of Gondwana� some geologists call southern hemisphere coal, gas, petroleum � and so the modern history of Gondwanaland is also a substantive history of the Anthropocene.
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Jones, Megan E., David H. Bromwich, Julien P. Nicolas, et al. "Sixty Years of Widespread Warming in the Southern Middle and High Latitudes (1957–2016)." Journal of Climate 32, no. 20 (2019): 6875–98. http://dx.doi.org/10.1175/jcli-d-18-0565.1.
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Abstract Temperature trends across Antarctica over the last few decades reveal strong and statistically significant warming in West Antarctica and the Antarctic Peninsula (AP) contrasting with no significant change overall in East Antarctica. However, recent studies have documented cooling in the AP since the late 1990s. This study aims to place temperature changes in the AP and West Antarctica into a larger spatial and temporal perspective by analyzing monthly station-based surface temperature observations since 1957 across the extratropical Southern Hemisphere, along with sea surface temperature (SST) data and mean sea level pressure reanalysis data. The results confirm statistically significant cooling in station observations and SST trends throughout the AP region since 1999. However, the full 60-yr period shows statistically significant, widespread warming across most of the Southern Hemisphere middle and high latitudes. Positive SST trends broadly reflect these warming trends, especially in the midlatitudes. After confirming the importance of the southern annular mode (SAM) on southern high-latitude climate variability, the influence is removed from the station temperature records, revealing statistically significant background warming across all of the extratropical Southern Hemisphere. Antarctic temperature trends in a suite of climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) are then investigated. Consistent with previous work the CMIP5 models warm Antarctica at the background temperature rate that is 2 times faster than that observed. However, removing the SAM influence from both CMIP5 and observed temperatures results in Antarctic trends that differ only modestly, perhaps due to natural multidecadal variability remaining in the observations.
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Porter, Andrew, and D. Denoon. "Settler Capitalism: The Dynamics of Dependent Development in the Southern Hemisphere." Economic History Review 38, no. 1 (1985): 172. http://dx.doi.org/10.2307/2596683.
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Roman Lopes, Alexandre, Zulema Abraham, Anderson Caproni, Jacques R. D. Lépine, and Jose W. S. Vilas-Boas. "NLTE NH3(J,K) = (1,1) observations towards southern hemisphere compact regions." Symposium - International Astronomical Union 206 (2002): 244–47. http://dx.doi.org/10.1017/s0074180900222481.
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We present NH3(J,K) = (1,1) observations toward CS(2,1) sources in the southern hemisphere, obtained with the Itapetinga Radio Telescope, that exhibit departure from LTE conditions. The mechanism of selective trapping in the hyperfine transitions of NH3(J, K) =(2,1)-(1,1) is invoked to explain the non-thermal population in the NH3(J, K) = (1,1) hyperfine states. This effect is relevant only when the width of the hyperfine lines lie between 0.3 and 0.6 km s−1. Due to this restriction, the assumption that the molecular cloud is formed by clumps, which produce spectra within this line-width interval seems to be a natural explanation for the non-thermal population. The observed spectra can be the result of the superposition of individual clump spectra with different central velocities. This model was applied to determine the physical conditions of the observed regions, providing satisfactory results for most of them. However, for some sources the model is not adequate to reproduce the observations, indicating that some other effects should be included, such as IR continuum, that was neglected in the radiative transfer calculations.
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Hill, Robert S., and Tim J. Brodribb. "Southern Conifers in Time and Space." Australian Journal of Botany 47, no. 5 (1999): 639. http://dx.doi.org/10.1071/bt98093.
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The three southern conifer families, Araucariaceae, Cupressaceae and Podocarpaceae, have a long history and continue to be an important part of the vegetation today. The Araucariaceae have the most extensive fossil record, occurring in both hemispheres, and with Araucaria in particular having an ancient origin. In the Southern Hemisphere Araucaria and Agathis have substantial macrofossil records, especially in Australasia, and Wollemia probably also has an important macrofossil record. At least one extinct genus of Araucariaceae is present as a macrofossil during the Cenozoic. Cupressaceae macrofossils are difficult to identify in older sediments, but the southern genera begin their record in the Cretaceous (Athrotaxis) and become more diverse and extensive during the Cenozoic. Several extinct genera of Cupressaceae also occur in Cretaceous and Cenozoic sediments in Australasia. The Podocarpaceae probably begin their macrofossil record in the Triassic, although the early history is still uncertain. Occasional Podocarpaceae macrofossils have been recorded in the Northern Hemisphere, but they are essentially a southern family. The Cenozoic macrofossil record of the Podocarpaceae is extensive, especially in south-eastern Australia, where the majority of the extant genera have been recorded. Some extinct genera have also been reported from across high southern latitudes, confirming an extremely diverse and widespread suite of Podocarpaceae during the Cenozoic in the region. In the Southern Hemisphere today conifers achieve greatest abundance in wet forests. Those which compete successfully with broad-leaved angiosperms in warmer forests produce broad, flat photosynthetic shoots. In the Araucariaceae this is achieved by the planation of multiveined leaves into large compound shoots. In the other two families leaves are now limited to a single vein (except Nageia), and to overcome this limitation many genera have resorted to re-orientation of leaves and two-dimensional flattening of shoots. The Podocarpaceae show greatest development of this strategy with 11 of 19 genera producing shoots analogous to compound leaves. The concentration of conifers in wet forest left them vulnerable to the climate change which occurred in the Cenozoic, and decreases in diversity have occurred since the Paleogene in all regions where fossil records are available. Information about the history of the dry forest conifers is extremely limited because of a lack of fossilisation in such environments. The southern conifers, past and present, demonstrate an ability to compete effectively with angiosperms in many habitats and should not be viewed as remnants which are ineffectual against angiosperm competitors.
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Battistel, Dario, Natalie M. Kehrwald, Piero Zennaro, et al. "High-latitude Southern Hemisphere fire history during the mid- to late Holocene (6000–750 BP)." Climate of the Past 14, no. 6 (2018): 871–86. http://dx.doi.org/10.5194/cp-14-871-2018.
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Abstract. We determined the specific biomass burning biomarker levoglucosan in an ice core from the TALos Dome Ice CorE drilling project (TALDICE) during the mid- to late Holocene (6000–750 BP). The levoglucosan record is characterized by a long-term increase with higher rates starting at ∼ 4000 BP and peaks between 2500 and 1500 BP. The anomalous increase in levoglucosan centered at ∼ 2000 BP is consistent with other Antarctic biomass burning records. Multiple atmospheric phenomena affect the coastal Antarctic Talos Dome drilling site, where the Southern Annular Mode (SAM) is the most prominent as the Southern Annular Mode Index (SAMA) correlates with stable isotopes in precipitation throughout the most recent 1000 years of the ice core. If this connection remains throughout the mid- to late Holocene, then our results demonstrate that changes in biomass burning, rather than changes in atmospheric transport, are the major influence on the TALDICE levoglucosan record. Comparisons with charcoal syntheses help evaluate fire sources, showing a greater contribution from southern South American fires than from Australian biomass burning. The levoglucosan peak centered at ∼ 2000 BP occurs during a cool period throughout the Southern Hemisphere, yet during a time of increased fire activity in both northern and southern Patagonia. This peak in biomass burning is influenced by increased vegetation in southern South America from a preceding humid period, in which the vegetation desiccated during the following cool, dry period. The Talos Dome ice core record from 6000 to ∼ 750 BP currently does not provide clear evidence that the fire record may be strongly affected by anthropogenic activities during the mid- to late Holocene, although we cannot exclude at least a partial influence.
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Van Den Broeke, Michiel R. "The semi-annual oscillation and Antarctic climate. Part 2: recent changes." Antarctic Science 10, no. 2 (1998): 184–91. http://dx.doi.org/10.1017/s095410209800025x.
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Following a weakening of the semi-annual oscillation (SAO) since the mid-1970s, the half-yearly pressure wave in the Southern Hemisphere has become less significant. As a result, May/June temperatures have decreased in East Antarctica, which has moderated Antarctic warming. Spectral analysis of 87 years of pressure data at Orcadas suggest that the recent weakening of the SAO is part of the natural variability of the Southern Hemisphere circulation on decadal timescales. We interpret the time series of composite Antarctic temperature in terms of the historical strengthening and weakening of the SAO. If the dominant oscillations that occurred in the past prove to be persistent, an accelerated East Antarctic warming trend is expected for the coming decades. There are indications that the strength of the SAO is linked to the Southern Oscillation, in the sense that warm phases of the Southern Oscillation coincide with strong westerlies, a weakly developed SAO and below-average temperatures in East Antarctica. Temperatures on the west coast of the Antarctic Peninsula show strongly deviant patterns, which can not be explained by the same mechanism that applies to East Antarctica.
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Pamungkas, J., CJ Glasby, and MJ Costello. "Biogeography of polychaete worms (Annelida) of the world." Marine Ecology Progress Series 657 (January 7, 2021): 147–59. http://dx.doi.org/10.3354/meps13531.
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The global biogeography of polychaete worms has never been assessed previously. In the present study, we studied the world distribution patterns of polychaetes based on datasets obtained from the Global Biodiversity Information Facility, the Ocean Biogeographic Information System and our recently published checklist of Indonesian polychaete species. Polychaete biogeographic regions were visualized using ‘Infomap Bioregions’, and the latitudinal species richness gradient of the animals was examined using 3 metrics, i.e. alpha, gamma and estimated species richness (the last metric was adjusted for sampling bias). We identified 11 major polychaete biogeographic regions. The North Atlantic, Australia and Indonesia were the top 3 species-rich biogeographic regions in the world. The total number of polychaete species was higher in the southern hemisphere (~2100 species, 67 families) than in the northern hemisphere (~1800 species, 75 families) despite significantly more data in the latter (>500000 records compared to >26000 records). Contrary to the classical idea of a unimodal distribution pattern, the latitudinal gradient of polychaetes was generally bimodal with a pronounced dip north of the Equator (15°N). We suggest that the slightly higher peak of species richness in the southern (30°S) than in the northern (60°N) hemisphere reflects higher southern endemicities. These patterns are unlikely to be due to sampling bias but rather represent a natural phenomenon, and we found them most significantly correlated with sea temperature.
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Gasse, Françoise, and Elise Van Campo. "A 40,000-yr Pollen and Diatom Record from Lake Tritrivakely, Madagascar, in the Southern Tropics." Quaternary Research 49, no. 3 (1998): 299–311. http://dx.doi.org/10.1006/qres.1998.1967.
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Links between southern and northern hemisphere climates during the Late Quaternary are poorly known, partly due to the scarcity of continuous climatic records in the southern tropics. Pollen and diatom evidence from Lake Tritrivakely (19°47′S) provides information on vegetational and hydrological changes in the central highlands of Madagascar over the past 40,000 yr. Most of the record reflects natural environmental variability since humans arrived on the island ca. 2000 yr B.P. During glacial times, the migration of mountain plants toward lower altitudes is consistent with a temperature decrease and with reduced atmospheric CO2 levels. In the lake, a positive mean annual hydrologic balance, from 38,000 to 36,000 and from 17,500 to 9800 cal yr B.P., coincided with periods of decreasing summer insolation and preceded by several millennia lake rises in the northern tropics. A negative hydrologic budget during periods of maximum seasonal contrast in solar radiation is partly attributed to high summer evaporation rate. The last glacial maximum was cool and dry. The deglacial warming occurred in two steps. The first step, accompanied by an increase in wetness, occurred abruptly at ca. 17,000 cal yr B.P., about two millennia earlier than in the northern hemisphere. It is abundantly documented in southern terrestrial data. The second step, at 15,000 cal yr B.P., was in phase with the first major temperature change in the northern hemisphere.
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Alberti, T., F. Lepreti, A. Vecchio, E. Bevacqua, V. Capparelli, and V. Carbone. "Natural periodicities and Northern Hemisphere–Southern Hemisphere connection of fast temperature changes during the last glacial period: EPICA and NGRIP revisited." Climate of the Past 10, no. 5 (2014): 1751–62. http://dx.doi.org/10.5194/cp-10-1751-2014.
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Abstract. We investigate both the European Project for Ice Coring in Antarctica Dronning Maud Land (EDML) and North Greenland Ice-Core Project (NGRIP) data sets to study both the time evolution of the so-called Dansgaard–Oeschger events and the dynamics at longer timescales during the last glacial period. Empirical mode decomposition (EMD) is used to extract the proper modes of both the data sets. It is shown that the time behavior at the typical timescales of Dansgaard–Oeschger events is captured through signal reconstructions obtained by summing five EMD modes for NGRIP and four EMD modes for EDML. The reconstructions obtained by summing the successive modes can be used to describe the climate evolution at longer timescales, characterized by intervals in which Dansgaard–Oeschger events happen and intervals when these are not observed. Using EMD signal reconstructions and a simple model based on the one-dimensional Langevin equation, it is argued that the occurrence of a Dansgaard–Oeschger event can be described as an excitation of the climate system within the same state, while the longer timescale behavior appears to be due to transitions between different climate states. Finally, on the basis of a cross-correlation analysis performed on EMD reconstructions, evidence that the Antarctic climate changes lead those of Greenland by a lag of ≈ 3.05 kyr is presented.
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Prather, Michael J. "CO<sub>2</sub> surface variability: from the stratosphere or not?" Earth System Dynamics 13, no. 2 (2022): 703–9. http://dx.doi.org/10.5194/esd-13-703-2022.
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Abstract. Fluctuations in atmospheric CO2 can be measured with great precision and are used to identify human-driven sources as well as natural cycles of ocean and land carbon. One source of variability is the stratosphere, where the influx of aged CO2-depleted air can produce fluctuations at the surface. This process has been speculated to be a potential source of interannual variability (IAV) in CO2 that might obscure the quantification of other sources of IAV. Given the recent success in demonstrating that the stratospheric influx of N2O- and chlorofluorocarbon-depleted air is a dominant source of their surface IAV in the Southern Hemisphere, I apply the same model and measurement analysis here to CO2. Using chemistry-transport modeling or scaling of the observed N2O variability, I find that the stratosphere-driven surface variability in CO2 is at most 10 % of the observed IAV and is not an important source. Diagnosing the amplitude of the CO2 annual cycle and its increase from 1985 to 2021 through the annual variance gives rates similar to traditional methods in the Northern Hemisphere (BRW, MLO) but can identify the emergence of small trends (0.08 ppm per decade) in the Southern Hemisphere (SMO, CGO).
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Dergunov, Alexander V., Valentin B. Kashkin, Тatyana V. Rubleva, Alexey A. Romanov, and Roman V. Odintsov. "ANTARCTIC OZONE HOLE AS A NATURAL GEOPHYSICAL OBJECT." E3S Web of Conferences 75 (2019): 02008. http://dx.doi.org/10.1051/e3sconf/20197502008.
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Satellite data on total ozone content for 1985-2015 have been used. Methods of evaluating ozone deficit in the polar region and its excess in middle latitudes of the Southern Hemisphere have been developed. In early spring the ozone molecules outflow and the ozone anomaly forms. Ozone inflows the middle latitudes, its total content increases and a ring with elevated TO forms. In October-November the dynamic process reverses, from the ring the ozone molecules transfer to the polar latitudes. The amount of ozone leaving the ring into the polar regions and filling the ozone anomaly is virtually the same. The results produces indicate that the Antarctic ozone hole is a natural geophysical formation.