Journal articles: 'Paleoclimate modelling'

1

Hill, Kathryn E., Stuart C. Brown, Alice Jones, Damien Fordham, and Robert S. Hill. "Modelling Climate Using Leaves of Nothofagus cunninghamii—Overcoming Confounding Factors." Sustainability 15, no. 9 (May 5, 2023): 7603. http://dx.doi.org/10.3390/su15097603.

Full text

Abstract:

Fossil leaf anatomy has previously been used as a proxy for paleoclimate. However, the exposure of leaves to sun or shade during their growth can lead to morphotype differences that confound the interpretation of fossil leaf anatomy in relation to climate and prevent reliable paleoclimate reconstruction. This work aims to model the differences in leaf anatomy that are due to various climatic drivers and differences attributable to sun or shade positions, using Nothofagus cunninghamii as the model species. Leaves from the sun and shade parts of three trees have been sampled from each of 11 sites in Victoria and Tasmania, Australia. The gross morphological and cuticular features have been scored and modelled with climate data from the sites. Random forest models can accurately predict Nothofagus cunninghamii contemporary climatic conditions of the spring temperature and summer rainfall based on leaf anatomical measurements. Leaf area, stomatal density and epidermal cell density are the most accurate predictors of whether a leaf grew in the sun or shade. Leaf area is also the strongest predictor of the maximum and minimum spring temperatures and rainfall. The models have implications for the use of fossilised leaves in paleoclimate reconstruction. The models we have built can be used to effectively predict whether a fossil leaf was from a sun or shade position on the tree and thus enable more reliable inference of paleoclimate by removing the confounding issues of variable leaf anatomy due to sun exposure during growth. Finally, these models could conceivably be used to make predictions of past paleoclimatic conditions provided suitable training and validation data on climatic conditions are available.

APA, Harvard, Vancouver, ISO, and other styles

2

Bracaconnot, Pascale, and Sandy P. Harrison. "PMIP (Paleoclimate Modelling Intercomparison Project)." PAGES news 16, no. 2 (April 2008): 31–32. http://dx.doi.org/10.22498/pages.16.2.31.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Crucifix, M., P. Braconnot, S. P. Harrison, and B. Otto-Bliesner. "Second phase of paleoclimate modelling intercomparison project." Eos, Transactions American Geophysical Union 86, no. 28 (2005): 264. http://dx.doi.org/10.1029/2005eo280003.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Sueyoshi, T., R. Ohgaito, A. Yamamoto, M. O. Chikamoto, T. Hajima, H. Okajima, M. Yoshimori, et al. "Setup of the PMIP3 paleoclimate experiments conducted using an Earth System Model, MIROC-ESM." Geoscientific Model Development Discussions 5, no. 3 (September 3, 2012): 2527–69. http://dx.doi.org/10.5194/gmdd-5-2527-2012.

Full text

Abstract:

Abstract. The importance of climate model evaluation using paleoclimate simulations for better future climate projections has been recognized by the Intergovernmental Panel on Climate Change. In recent years, Earth System Models (ESMs) were developed to investigate carbon-cycle climate feedback, as well as to project the future climate. Paleoclimate events, especially those associated with the variations in atmospheric CO2 level or land vegetation, provide suitable benchmarks to evaluate ESMs. Here we present implementations of the paleoclimate experiments proposed by the Coupled Model Intercomparison Project phase 5/Paleoclimate Modelling Intercomparison Project phase 3 (CMIP5/PMIP3) using an Earth System Model, MIROC-ESM. In this paper, experimental settings and procedures of the mid-Holocene, the Last Glacial Maximum, and the Last Millennium experiments are explained. The first two experiments are time slice experiments and the last one is a transient experiment. The complexity of the model requires various steps to correctly configure the experiments. Several basic outputs are also shown.

APA, Harvard, Vancouver, ISO, and other styles

5

Baker, Andy. "Forward modelling of the speleothem oxygen isotope paleoclimate proxy." Quaternary International 279-280 (November 2012): 34. http://dx.doi.org/10.1016/j.quaint.2012.07.147.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Brierley, Chris, Kaustubh Thirumalai, Edward Grindrod, and Jonathan Barnsley. "Indian Ocean variability changes in the Paleoclimate Modelling Intercomparison Project." Climate of the Past 19, no. 3 (March 27, 2023): 681–701. http://dx.doi.org/10.5194/cp-19-681-2023.

Full text

Abstract:

Abstract. The Indian Ocean exhibits multiple modes of interannual climate variability, whose future behaviour is uncertain. Recent analysis of glacial climates has uncovered an additional El Niño-like equatorial mode in the Indian Ocean, which could also emerge in future warm states. Here we explore changes in the tropical Indian Ocean simulated by the Paleoclimate Model Intercomparison Project (PMIP4). These simulations are performed by an ensemble of models contributing to the Coupled Model Intercomparison Project 6 and over four coordinated experiments: three past periods – the mid-Holocene (6000 years ago), the Last Glacial Maximum (21 000 years ago), the last interglacial (127 000 years ago) – and an idealized forcing scenario to examine the impact of greenhouse forcing. The two interglacial experiments are used to characterize the role of orbital variations in the seasonal cycle, whilst the other pair focus on responses to large changes in global temperature. The Indian Ocean Basin Mode (IOBM) is damped in both the mid-Holocene and last interglacial, with the amount related to the damping of the El Niño–Southern Oscillation in the Pacific. No coherent changes in the strength of the IOBM are seen with global temperature changes; neither are changes in the Indian Ocean Dipole (IOD) nor the Niño-like mode. Under orbital forcing, the IOD robustly weakens during the mid-Holocene experiment, with only minor reductions in amplitude during the last interglacial. Orbital changes do impact the SST pattern of the Indian Ocean Dipole, with the cold pole reaching up to the Equator and extending along it. Induced changes in the regional seasonality are hypothesized to be an important control on changes in the Indian Ocean variability.

APA, Harvard, Vancouver, ISO, and other styles

7

Sueyoshi, T., R. Ohgaito, A. Yamamoto, M. O. Chikamoto, T. Hajima, H. Okajima, M. Yoshimori, et al. "Set-up of the PMIP3 paleoclimate experiments conducted using an Earth system model, MIROC-ESM." Geoscientific Model Development 6, no. 3 (June 21, 2013): 819–36. http://dx.doi.org/10.5194/gmd-6-819-2013.

Full text

Abstract:

Abstract. Paleoclimate experiments using contemporary climate models are an effective measure to evaluate climate models. In recent years, Earth system models (ESMs) were developed to investigate carbon cycle climate feedbacks, as well as to project the future climate. Paleoclimate events can be suitable benchmarks to evaluate ESMs. The variation in aerosols associated with the volcanic eruptions provide a clear signal in forcing, which can be a good test to check the response of a climate model to the radiation changes. The variations in atmospheric CO2 level or changes in ice sheet extent can be used for evaluation as well. Here we present implementations of the paleoclimate experiments proposed by the Coupled Model Intercomparison Project phase 5/Paleoclimate Modelling Intercomparison Project phase 3 (CMIP5/PMIP3) using MIROC-ESM, an ESM based on the global climate model MIROC (Model for Interdisciplinary Research on Climate). In this paper, experimental settings and spin-up procedures of the mid-Holocene, the Last Glacial Maximum, and the Last Millennium experiments are explained. The first two experiments are time slice experiments and the last one is a transient experiment. The complexity of the model requires various steps to correctly configure the experiments. Several basic outputs are also shown.

APA, Harvard, Vancouver, ISO, and other styles

8

Hargreaves, J. C., and J. D. Annan. "The importance of paleoclimate modelling for improving predictions of future climate change." Climate of the Past Discussions 5, no. 4 (July 29, 2009): 2053–80. http://dx.doi.org/10.5194/cpd-5-2053-2009.

Full text

Abstract:

Abstract. We use an ensemble of runs from the MIROC3.2 AGCM with slab-ocean to explore the extent to which mid-Holocene simulations are relevant to predictions of future climate change. The results are compared with similar analyses for the Last Glacial Maximum (LGM) and pre-industrial control climate. We find evidence that the paleoclimate epochs can provide some independent validation of the models that is also relevant for future predictions. Considering the paleoclimate epochs, we find that the stronger global forcing and hence larger climate change at the LGM makes this likely to be the more powerful one for estimating the large-scale changes that are anticipated due to anthropogenic forcing. The regions from the mid-Holocene simulations which produce significant results (mid to high northern latitude land temperature and monsoon precipitation) do, however, coincide with areas where the LGM results are weak, and are also areas where the paleodata indicate significant climate changes have occurred. Thus, these areas should be a high priority for model improvement and validation.

APA, Harvard, Vancouver, ISO, and other styles

9

Hartmann, A., and A. Baker. "Modelling karst vadose zone hydrology and its relevance for paleoclimate reconstruction." Earth-Science Reviews 172 (September 2017): 178–92. http://dx.doi.org/10.1016/j.earscirev.2017.08.001.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Hargreaves, J. C., and J. D. Annan. "On the importance of paleoclimate modelling for improving predictions of future climate change." Climate of the Past 5, no. 4 (December 21, 2009): 803–14. http://dx.doi.org/10.5194/cp-5-803-2009.

Full text

Abstract:

Abstract. We use an ensemble of runs from the MIROC3.2 AGCM with slab-ocean to explore the extent to which mid-Holocene simulations are relevant to predictions of future climate change. The results are compared with similar analyses for the Last Glacial Maximum (LGM) and pre-industrial control climate. We suggest that the paleoclimate epochs can provide some independent validation of the models that is also relevant for future predictions. Considering the paleoclimate epochs, we find that the stronger global forcing and hence larger climate change at the LGM makes this likely to be the more powerful one for estimating the large-scale changes that are anticipated due to anthropogenic forcing. The phenomena in the mid-Holocene simulations which are most strongly correlated with future changes (i.e., the mid to high northern latitude land temperature and monsoon precipitation) do, however, coincide with areas where the LGM results are not correlated with future changes, and these are also areas where the paleodata indicate significant climate changes have occurred. Thus, these regions and phenomena for the mid-Holocene may be useful for model improvement and validation.

APA, Harvard, Vancouver, ISO, and other styles

11

Renoult, Martin, Navjit Sagoo, Jiang Zhu, and Thorsten Mauritsen. "Causes of the weak emergent constraint on climate sensitivity at the Last Glacial Maximum." Climate of the Past 19, no. 2 (February 2, 2023): 323–56. http://dx.doi.org/10.5194/cp-19-323-2023.

Full text

Abstract:

Abstract. The use of paleoclimates to constrain the equilibrium climate sensitivity (ECS) has seen a growing interest. In particular, the Last Glacial Maximum (LGM) and the mid-Pliocene warm period have been used in emergent-constraint approaches using simulations from the Paleoclimate Modelling Intercomparison Project (PMIP). Despite lower uncertainties regarding geological proxy data for the LGM in comparison with the Pliocene, the robustness of the emergent constraint between LGM temperature and ECS is weaker at both global and regional scales. Here, we investigate the climate of the LGM in models through different PMIP generations and how various factors in the atmosphere, ocean, land surface and cryosphere contribute to the spread of the model ensemble. Certain factors have a large impact on an emergent constraint, such as state dependency in climate feedbacks or model dependency on ice sheet forcing. Other factors, such as models being out of energetic balance and sea surface temperature not responding below −1.8 ∘C in polar regions, have a limited influence. We quantify some of the contributions and find that they mostly have extratropical origins. Contrary to what has previously been suggested, from a statistical point of view, the PMIP model generations do not differ substantially. Moreover, we show that the lack of high- or low-ECS models in the ensembles critically limits the strength and reliability of the emergent constraints. Single-model ensembles may be promising tools for the future of LGM emergent constraint, as they permit a large range of ECS and reduce the noise from inter-model structural issues. Finally, we provide recommendations for a paleo-based emergent constraint and notably which paleoclimate is ideal for such an approach.

APA, Harvard, Vancouver, ISO, and other styles

12

Vadsaria, Tristan, Laurent Li, Gilles Ramstein, and Jean-Claude Dutay. "Development of a sequential tool, LMDZ-NEMO-med-V1, to conduct global-to-regional past climate simulation for the Mediterranean basin: an Early Holocene case study." Geoscientific Model Development 13, no. 5 (May 19, 2020): 2337–54. http://dx.doi.org/10.5194/gmd-13-2337-2020.

Full text

Abstract:

Abstract. Recently, major progress has been made in the simulation of the ocean dynamics of the Mediterranean using atmospheric and oceanic models with high spatial resolution. High resolution is essential to accurately capture the synoptic variability required to initiate intermediate- and deep-water formation, the engine of the Mediterranean thermohaline circulation (MTC). In paleoclimate studies, one major problem with the simulation of regional climate changes is that boundary conditions are not available from observations or data reconstruction to drive high-resolution regional models. One consistent way to advance paleoclimate modelling is to use a comprehensive global-to-regional approach. However, this approach needs long-term integration to reach equilibrium (hundreds of years), implying enormous computational resources. To tackle this issue, a sequential architecture of a global–regional modelling platform has been developed for the first time and is described in detail in this paper. First of all, the platform is validated for the historical period. It is then used to investigate the climate and in particular, the oceanic circulation, during the Early Holocene. This period was characterised by a large reorganisation of the MTC that strongly affected oxygen supply to the intermediate and deep waters, which ultimately led to an anoxic crisis (called sapropel). Beyond the case study shown here, this platform may be applied to a large number of paleoclimate contexts from the Quaternary to the Pliocene, as long as regional tectonics remain mostly unchanged. For example, the climate responses of the Mediterranean basin during the last interglacial period (LIG), the Last Glacial Maximum (LGM) and the Late Pliocene all present interesting scientific challenges which may be addressed using this numerical platform.

APA, Harvard, Vancouver, ISO, and other styles

13

Quinn, Courtney, Jan Sieber, and Anna S. von der Heydt. "Effects of Periodic Forcing on a Paleoclimate Delay Model." SIAM Journal on Applied Dynamical Systems 18, no. 2 (January 2019): 1060–77. http://dx.doi.org/10.1137/18m1203079.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Jiang, Dabang, and Zhongshi Zhang. "Paleoclimate modelling at the Institute of Atmospheric Physics, Chinese Academy of Sciences." Advances in Atmospheric Sciences 23, no. 6 (December 2006): 1040–49. http://dx.doi.org/10.1007/s00376-006-1040-z.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Ramstein, G., M. Kageyama, J. Guiot, H. Wu, C. Hély, G. Krinner, and S. Brewer. "How cold was Europe at the Last Glacial Maximum? A synthesis of the progress achieved since the first PMIP model-data comparison." Climate of the Past 3, no. 2 (June 18, 2007): 331–39. http://dx.doi.org/10.5194/cp-3-331-2007.

Full text

Abstract:

Abstract. The Last Glacial Maximum has been one of the first foci of the Paleoclimate Modelling Intercomparison Project (PMIP). During its first phase, the results of 17 atmosphere general circulation models were compared to paleoclimate reconstructions. One of the largest discrepancies in the simulations was the systematic underestimation, by at least 10°C, of the winter cooling over Europe and the Mediterranean region observed in the pollen-based reconstructions. In this paper, we investigate the progress achieved to reduce this inconsistency through a large modelling effort and improved temperature reconstructions. We show that increased model spatial resolution does not significantly increase the simulated LGM winter cooling. Further, neither the inclusion of a vegetation cover compatible with the LGM climate, nor the interactions with the oceans simulated by the atmosphere-ocean general circulation models run in the second phase of PMIP result in a better agreement between models and data. Accounting for changes in interannual variability in the interpretation of the pollen data does not result in a reduction of the reconstructed cooling. The largest recent improvement in the model-data comparison has instead arisen from a new climate reconstruction based on inverse vegetation modelling, which explicitly accounts for the CO2 decrease at LGM and which substantially reduces the LGM winter cooling reconstructed from pollen assemblages. As a result, the simulated and observed LGM winter cooling over Western Europe and the Mediterranean area are now in much better agreement.

APA, Harvard, Vancouver, ISO, and other styles

16

Ramstein, G., M. Kageyama, J. Guiot, H. Wu, C. Hély, G. Krinner, and S. Brewer. "How cold was Europe at the Last Glacial Maximum? A synthesis of the progress achieved since the first PMIP model-data comparison." Climate of the Past Discussions 3, no. 1 (January 22, 2007): 197–220. http://dx.doi.org/10.5194/cpd-3-197-2007.

Full text

Abstract:

Abstract. The Last Glacial Maximum has been one of the first foci of the Paleoclimate Modelling Intercomparison Project (PMIP). During its first phase, the results of 17 atmosphere general circulation models were compared to paleoclimate reconstructions. One of the largest discrepancies in the simulations was the systematic underestimation, by at least 10°C, of the winter cooling over Europe and the Mediterranean region observed in the pollen-based reconstructions. In this paper, we investigate the progress achieved to reduce this inconsistency through a large modelling effort and improved temperature reconstructions. We show that increased model spatial resolution does not significantly increase the simulated LGM winter cooling. Further, neither the inclusion of a vegetation cover compatible with the LGM climate, nor the interactions with the oceans simulated by the atmosphere-ocean general circulation models run in the second phase of PMIP result in a better agreement between models and data. Accounting for changes in interannual variability in the interpretation of the pollen data does not result in a reduction of the reconstructed cooling. The largest recent improvement in the model-data comparison has instead arisen from a new climate reconstruction based on inverse vegetation modelling, which explicitly accounts for the CO2 decrease at LGM and which substantially reduces the LGM winter cooling reconstructed from pollen assemblages. As a result, the simulated and observed LGM winter cooling over Western Europe and the Mediterranean area are now in much better agreement.

APA, Harvard, Vancouver, ISO, and other styles

17

Martin, Ronald E. "Time and taphonomy: Actualistic evidence for time-averaging of benthic foraminiferal assemblages." Short Courses in Paleontology 6 (1993): 34–56. http://dx.doi.org/10.1017/s2475263000001045.

Full text

Abstract:

For more than half a century, microfossils–especially foraminifera–have been widely used as stratigraphic markers and paleoenvironmental indicators. Although increasing emphasis has been placed on their use in high-resolution paleoclimate studies, the time-scales involved in most microfossil-based stratigraphic investigations have remained relatively coarse (hundreds-of-thousands to millions of years). My intent herein is to try to come to grips with the interplay between time-averaging of benthic foraminiferal assemblages and stratigraphic resolution, and the implications for recognition of short-term physical and biological processes. These sorts of considerations deserve much closer scrutiny as the applied Earth sciences continue to move from a base of resource exploration and exploitation to one of paleoclimate modelling and ecosystem management (Martin, 1991; Corliss, 1993). The potential stratigraphic and paleoenvironmental resolution of foraminiferal assemblages is assessed using concepts derived from the age analysis of deep-sea assemblages.

APA, Harvard, Vancouver, ISO, and other styles

18

Berger, M., J. Brandefelt, and J. Nilsson. "Arctic sea ice in the mid-Holocene Paleoclimate Modelling Intercomparison Project 2 simulations." Climate of the Past Discussions 8, no. 4 (August 13, 2012): 3445–80. http://dx.doi.org/10.5194/cpd-8-3445-2012.

Full text

Abstract:

Abstract. The Arctic sea ice in the mid-Holocene simulations of 11 coupled global circulation models part of the Paleoclimate Modelling Intercomparison Project phase 2 (PMIP2) is analysed in this study. The work includes a comparison of the mid-Holocene simulations to the pre-industrial control simulations for each individual model and also a model-model comparison. The forcing conditions in the mid-Holocene and pre-industrial simulations differ in the atmospheric methane concentration and the latitudinal and monthly distribution of solar insolation (due to differences in the orbital parameters). Other studies have found that the difference in insolation, with increased northern hemisphere summer insolation, explain the major differences between the simulated mid-Holocene and pre-industrial climates. The response of the simulated sea ice extent and thickness to the changes in solar insolation and atmospheric greenhouse gases is investigated. The model-model variation in pre-industrial simulated Arctic sea ice is large, with sea ice area extent ranging from 10.1 to 28.2 (7.01 to 24.6) million km2 in March (September), and the maximum sea ice thickness ranging from 1.5 m to more than 5 m in both September and March. Nevertheless, all models agree on the sign of the difference between mid-Holocene and pre-industrial in both March and September. All models have smaller summer sea ice extent and thinner ice cover in all seasons in the mid-Holocene climate compared to the control (pre-industrial) climate. The reduction in sea ice extent is mostly confined to the sea ice margins, whereas the thinning of the ice occurs over the entire ice cover. In addition, the models also experience an enhanced summer warming north of 60° N. For the central Arctic region, models with thicker ice in the mean state in the control simulation experience the largest change in the mean state between the two climates. Comparison to available Climate Model Intercomparison Project 3 (CMIP3) simulations with the same model version and atmospheric CO2 concentration increased to a doubling has also been performed. The sea ice response in this future scenario is stronger than the response in the mid-Holocene simulation. Again we find that the model with the thickest mean state has the largest response.

APA, Harvard, Vancouver, ISO, and other styles

19

Frappier, Amy, Thomas Knutson, Kam-Biu Liu, and Kerry Emanuel. "Perspective: coordinating paleoclimate research on tropical cyclones with hurricane-climate theory and modelling." Tellus A: Dynamic Meteorology and Oceanography 59, no. 4 (January 1, 2007): 529–37. http://dx.doi.org/10.1111/j.1600-0870.2007.00250.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Iyer, Karthik, Daniel W. Schmid, Sverre Planke, and John Millett. "Modelling hydrothermal venting in volcanic sedimentary basins: Impact on hydrocarbon maturation and paleoclimate." Earth and Planetary Science Letters 467 (June 2017): 30–42. http://dx.doi.org/10.1016/j.epsl.2017.03.023.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

He, Zhilin, Zhongshi Zhang, and Zhengtang Guo. "Reconstructing early Eocene (∼55 Ma) paleogeographic boundary conditions for use in paleoclimate modelling." Science China Earth Sciences 62, no. 9 (June 21, 2019): 1416–27. http://dx.doi.org/10.1007/s11430-019-9366-2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Kypke, Kolja L., and William F. Langford. "Topological Climate Change." International Journal of Bifurcation and Chaos 30, no. 02 (February 2020): 2030005. http://dx.doi.org/10.1142/s0218127420300050.

Full text

Abstract:

This article presents a bifurcation analysis of a simple Energy Balance Model (EBM) of the Earth’s climate, which suggests that topological change has occurred in the paleoclimate history of the Earth. In the theory of dynamical systems, two systems that are topologically equivalent have solutions with the same qualitative behavior. A change in the topological equivalence class, as parameters are varied, is called a bifurcation. Thus, a bifurcation demarcates a significant change in the behavior of the solutions of a dynamical system. If that system represents climate, then that topological change may represent an abrupt transformation of the climate, occurring even with a very small change in the forcing parameters. In this paper, the existence of a cusp bifurcation is proven in a climate EBM. The existence of this cusp bifurcation implies the co-existence of two distinct stable equilibrium climate states (bistability), as well as the existence of abrupt transitions between these two states (fold bifurcations) in the EBM. These transitions are dependent on the past history of the system (hysteresis). The two universal unfolding parameters for the cusp bifurcation have been determined as functions of the relevant physical parameters. These ideas lead to the proposal of a new explanation for the so-called warm equable climate problem of the mid-Cretaceous and early Eocene. The analysis presented here implies that the mid-Cretaceous and early Eocene climate systems are topologically equivalent to each other, but they are not topologically equivalent to the preindustrial modern climate. The transition from the warm, equable paleoclimate to today’s cooler nonequable climate occurs via fold (or saddle-node) bifurcations in the EBM, which correspond to the Eocene-Oligocene Transition (EOT) at the south pole and the Pliocene-Pleistocene Transition (PPT) at the north pole, in the paleoclimate record of Earth.

APA, Harvard, Vancouver, ISO, and other styles

23

Ploskov, A. N., A. V. Eliseev, and I. I. Mokhov. "ENSEMBLE MODELLING OF ICE SHEET DYNAMICS IN THE LAST GLACIAL CYCLE." Доклады Российской академии наук. Науки о Земле 510, no. 1 (May 1, 2023): 99–105. http://dx.doi.org/10.31857/s2686739722602873.

Full text

Abstract:

Ensemble simulations (taking into account uncertainty of paleoclimate reconstructions) with a models for ice sheets dynamics for the last glacial cycle (last 128 kyr) are carried out. The model realistically reproduces spatial structure of major ice sheets and heights of their domes in the Northern hemisphere as well as the associated changes in global sea level. Perturbations with a sufficiently large amplitude applied to the initial paleoreconstruction result in marked differences of the modelling, in particular, durimg the Last Glacial maximu and during 58–51 kyr before present (the initial part of MIS3). According to our simualtions, the uncertainty of temperature reconstructions durng the last galcial cycle is limited to 2°C in agreement with existing estimates.

APA, Harvard, Vancouver, ISO, and other styles

24

Schmidt, G. A., J. H. Jungclaus, C. M. Ammann, E. Bard, P. Braconnot, T. J. Crowley, G. Delaygue, et al. "Climate forcing reconstructions for use in PMIP simulations of the last millennium (v1.0)." Geoscientific Model Development 4, no. 1 (January 21, 2011): 33–45. http://dx.doi.org/10.5194/gmd-4-33-2011.

Full text

Abstract:

Abstract. Simulations of climate over the Last Millennium (850–1850 CE) have been incorporated into the third phase of the Paleoclimate Modelling Intercomparison Project (PMIP3). The drivers of climate over this period are chiefly orbital, solar, volcanic, changes in land use/land cover and some variation in greenhouse gas levels. While some of these effects can be easily defined, the reconstructions of solar, volcanic and land use-related forcing are more uncertain. We describe here the approach taken in defining the scenarios used in PMIP3, document the forcing reconstructions and discuss likely implications.

APA, Harvard, Vancouver, ISO, and other styles

25

Schmidt, G. A., J. H. Jungclaus, C. M. Ammann, E. Bard, P. Braconnot, T. J. Crowley, G. Delaygue, et al. "Climate forcing reconstructions for use in PMIP simulations of the last millennium (v1.0)." Geoscientific Model Development Discussions 3, no. 3 (September 27, 2010): 1549–86. http://dx.doi.org/10.5194/gmdd-3-1549-2010.

Full text

Abstract:

Abstract. Simulations of climate over the Last Millennium (850–1850 CE) have been incorporated into the third phase of the Paleoclimate Modelling Intercomparison Project (PMIP3). The drivers of climate over this period are chiefly orbital, solar, volcanic, changes in land use/land cover and some variation in greenhouse gas levels. While some of these effects can be easily defined, the reconstructions of solar, volcanic and land use-related forcing are more uncertain. We describe here the approach taken in defining the scenarios used in PMIP3, document the forcing reconstructions and discuss likely implications.

APA, Harvard, Vancouver, ISO, and other styles

26

Renssen, H., R. F. B. Isarin, J. Vandenberghe, M. Lautenschlager, and U. Schlese. "Permafrost as a critical factor in paleoclimate modelling: the Younger Dryas case in Europe." Earth and Planetary Science Letters 176, no. 1 (February 2000): 1–5. http://dx.doi.org/10.1016/s0012-821x(99)00322-2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Parnell, Andrew C. "A Bayesian multinomial regression model for paleoclimate reconstruction with time uncertainty." Environmetrics 27, no. 7 (October 4, 2016): 431–33. http://dx.doi.org/10.1002/env.2401.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Zhang, Qiong, Ellen Berntell, Josefine Axelsson, Jie Chen, Zixuan Han, Wesley de Nooijer, Zhengyao Lu, et al. "Simulating the mid-Holocene, last interglacial and mid-Pliocene climate with EC-Earth3-LR." Geoscientific Model Development 14, no. 2 (February 26, 2021): 1147–69. http://dx.doi.org/10.5194/gmd-14-1147-2021.

Full text

Abstract:

Abstract. As global warming is proceeding due to rising greenhouse gas concentrations, the Earth system moves towards climate states that challenge adaptation. Past Earth system states are offering possible modelling systems for the global warming of the coming decades. These include the climate of the mid-Pliocene (∼ 3 Ma), the last interglacial (∼ 129–116 ka) and the mid-Holocene (∼ 6 ka). The simulations for these past warm periods are the key experiments in the Paleoclimate Model Intercomparison Project (PMIP) phase 4, contributing to phase 6 of the Coupled Model Intercomparison Project (CMIP6). Paleoclimate modelling has long been regarded as a robust out-of-sample test bed of the climate models used to project future climate changes. Here, we document the model setup for PMIP4 experiments with EC-Earth3-LR and present the large-scale features from the simulations for the mid-Holocene, the last interglacial and the mid-Pliocene. Using the pre-industrial climate as a reference state, we show global temperature changes, large-scale Hadley circulation and Walker circulation, polar warming, global monsoons and the climate variability modes – El Niño–Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO). EC-Earth3-LR simulates reasonable climate responses during past warm periods, as shown in the other PMIP4-CMIP6 model ensemble. The systematic comparison of these climate changes in past three warm periods in an individual model demonstrates the model's ability to capture the climate response under different climate forcings, providing potential implications for confidence in future projections with the EC-Earth model.

APA, Harvard, Vancouver, ISO, and other styles

29

Fernández-Donado, L., J. F. González-Rouco, C. C. Raible, C. M. Ammann, D. Barriopedro, E. García-Bustamante, J. H. Jungclaus, et al. "Large-scale temperature response to external forcing in simulations and reconstructions of the last millennium." Climate of the Past 9, no. 1 (February 14, 2013): 393–421. http://dx.doi.org/10.5194/cp-9-393-2013.

Full text

Abstract:

Abstract. Understanding natural climate variability and its driving factors is crucial to assessing future climate change. Therefore, comparing proxy-based climate reconstructions with forcing factors as well as comparing these with paleoclimate model simulations is key to gaining insights into the relative roles of internal versus forced variability. A review of the state of modelling of the climate of the last millennium prior to the CMIP5–PMIP3 (Coupled Model Intercomparison Project Phase 5–Paleoclimate Modelling Intercomparison Project Phase 3) coordinated effort is presented and compared to the available temperature reconstructions. Simulations and reconstructions broadly agree on reproducing the major temperature changes and suggest an overall linear response to external forcing on multidecadal or longer timescales. Internal variability is found to have an important influence at hemispheric and global scales. The spatial distribution of simulated temperature changes during the transition from the Medieval Climate Anomaly to the Little Ice Age disagrees with that found in the reconstructions. Thus, either internal variability is a possible major player in shaping temperature changes through the millennium or the model simulations have problems realistically representing the response pattern to external forcing. A last millennium transient climate response (LMTCR) is defined to provide a quantitative framework for analysing the consistency between simulated and reconstructed climate. Beyond an overall agreement between simulated and reconstructed LMTCR ranges, this analysis is able to single out specific discrepancies between some reconstructions and the ensemble of simulations. The disagreement is found in the cases where the reconstructions show reduced covariability with external forcings or when they present high rates of temperature change.

APA, Harvard, Vancouver, ISO, and other styles

30

Tian, Zhiping, Tim Li, Dabang Jiang, and Lin Chen. "Causes of ENSO Weakening during the Mid-Holocene." Journal of Climate 30, no. 17 (September 2017): 7049–70. http://dx.doi.org/10.1175/jcli-d-16-0899.1.

Full text

Abstract:

The causes of the change in amplitude of El Niño–Southern Oscillation (ENSO) during the mid-Holocene were investigated by diagnosing the model simulations that participated in the Paleoclimate Modelling Intercomparison Project phases 2 and 3. Consistent with paleoclimate records, 20 out of the 28 models reproduced weaker-than-preindustrial ENSO amplitude during the mid-Holocene. Two representative models were then selected to explore the underlying mechanisms of air–sea feedback processes. A mixed layer heat budget diagnosis indicated that the weakened ENSO amplitude was primarily attributed to the decrease in the Bjerknes thermocline feedback, while the meridional advective feedback also played a role. During the mid-Holocene, the thermocline response to a unit anomalous zonal wind stress forcing in the equatorial Pacific weakened in both models because of the increased ENSO meridional scale. A further investigation revealed that the greater ENSO meridional width was caused by the strengthening of the Pacific subtropical cell, which was attributed to the enhanced mean trade wind that resulted from the intensified Asian and African monsoon rainfall and associated large-scale east–west circulation in response to the mid-Holocene orbital forcing.

APA, Harvard, Vancouver, ISO, and other styles

31

Kageyama, Masa, Sandy P. Harrison, Marie-L. Kapsch, Marcus Lofverstrom, Juan M. Lora, Uwe Mikolajewicz, Sam Sherriff-Tadano, et al. "The PMIP4 Last Glacial Maximum experiments: preliminary results and comparison with the PMIP3 simulations." Climate of the Past 17, no. 3 (May 20, 2021): 1065–89. http://dx.doi.org/10.5194/cp-17-1065-2021.

Full text

Abstract:

Abstract. The Last Glacial Maximum (LGM, ∼ 21 000 years ago) has been a major focus for evaluating how well state-of-the-art climate models simulate climate changes as large as those expected in the future using paleoclimate reconstructions. A new generation of climate models has been used to generate LGM simulations as part of the Paleoclimate Modelling Intercomparison Project (PMIP) contribution to the Coupled Model Intercomparison Project (CMIP). Here, we provide a preliminary analysis and evaluation of the results of these LGM experiments (PMIP4, most of which are PMIP4-CMIP6) and compare them with the previous generation of simulations (PMIP3, most of which are PMIP3-CMIP5). We show that the global averages of the PMIP4 simulations span a larger range in terms of mean annual surface air temperature and mean annual precipitation compared to the PMIP3-CMIP5 simulations, with some PMIP4 simulations reaching a globally colder and drier state. However, the multi-model global cooling average is similar for the PMIP4 and PMIP3 ensembles, while the multi-model PMIP4 mean annual precipitation average is drier than the PMIP3 one. There are important differences in both atmospheric and oceanic circulations between the two sets of experiments, with the northern and southern jet streams being more poleward and the changes in the Atlantic Meridional Overturning Circulation being less pronounced in the PMIP4-CMIP6 simulations than in the PMIP3-CMIP5 simulations. Changes in simulated precipitation patterns are influenced by both temperature and circulation changes. Differences in simulated climate between individual models remain large. Therefore, although there are differences in the average behaviour across the two ensembles, the new simulation results are not fundamentally different from the PMIP3-CMIP5 results. Evaluation of large-scale climate features, such as land–sea contrast and polar amplification, confirms that the models capture these well and within the uncertainty of the paleoclimate reconstructions. Nevertheless, regional climate changes are less well simulated: the models underestimate extratropical cooling, particularly in winter, and precipitation changes. These results point to the utility of using paleoclimate simulations to understand the mechanisms of climate change and evaluate model performance.

APA, Harvard, Vancouver, ISO, and other styles

32

Kalugin, Andrey, and Polina Morozova. "Hydrometeorological Conditions of the Volga Flow Generation into the Caspian Sea during the Last Glacial Maximum." Climate 11, no. 2 (February 2, 2023): 36. http://dx.doi.org/10.3390/cli11020036.

Full text

Abstract:

The goal of this study is to evaluate annual and seasonal inflow from the Volga catchment area to the Caspian Sea during the Last Glacial Maximum (LGM ~21,000 years ago) using paleoclimate modeling data. The first approach is based on the LGM simulation by the general circulation models (GCMs) in the framework of the Paleoclimate Modelling Intercomparison Project (PMIP4) and the Coupled Modelling Intercomparison Project (CMIP6). We used four GCMs: INM-CM4-8, MIROC-ES2L, AWI-ESM1-1-LR, and MPI-ESM1-2-LR. The second approach is based on the spatially distributed process-based runoff generation model using PMIP4-CMIP6 model data as boundary conditions. The use of the hydrological ECOMAG model allows us to refine estimates of the Volga runoff in comparison to GCM calculations by considering seasonal features of runoff generation related to periglacial vegetation distribution, permafrost, and streamflow transformation along the channel network. The LGM is characterized by a high uncertainty in meteorological values calculated for the Volga basin using various GCMs. The share of runoff from the three most flooded months from the annual calculated in the LGM was 95%, according to INM-CM4-8, while other GCMs ranged from 69–78%. Three GCMs (MIROC-ES2L, AWI-ESM1-1-LR, and MPI-ESM1-2-LR) showed 83–88% of the present-day value of precipitation in the Volga basin during cooling for more than 10 °C, while INM-CM4-8 showed a two-fold decrease. According to hydrological modeling results using data from three models, the annual Volga runoff was significantly higher than the present-day value, and, when using data from INM-CM4-8, it was lower.

APA, Harvard, Vancouver, ISO, and other styles

33

Lehner, F., F. Joos, C. C. Raible, J. Mignot, A. Born, K. M. Keller, and T. F. Stocker. "Climate and carbon cycle dynamics in a CESM simulation from 850 to 2100 CE." Earth System Dynamics 6, no. 2 (July 10, 2015): 411–34. http://dx.doi.org/10.5194/esd-6-411-2015.

Full text

Abstract:

Abstract. Under the protocols of phase 3 of the Paleoclimate Modelling Intercomparison Project, a number of simulations were produced that provide a range of potential climate evolutions from the last millennium to the end of the current century. Here, we present the first simulation with the Community Earth System Model (CESM), which includes an interactive carbon cycle, that covers the last millennium. The simulation is continued to the end of the twenty-first century. Besides state-of-the-art forcing reconstructions, we apply a modified reconstruction of total solar irradiance to shed light on the issue of forcing uncertainty in the context of the last millennium. Nevertheless, we find that structural uncertainties between different models can still dominate over forcing uncertainty for quantities such as hemispheric temperatures or the land and ocean carbon cycle response. Compared to other model simulations, we find forced decadal-scale variability to occur mainly after volcanic eruptions, while during other periods internal variability masks potentially forced signals and calls for larger ensembles in paleoclimate modeling studies. At the same time, we were not able to attribute millennial temperature trends to orbital forcing, as has been suggested recently. The climate–carbon-cycle sensitivity in CESM during the last millennium is estimated to be between 1.0 and 2.1 ppm °C−1. However, the dependence of this sensitivity on the exact time period and scale illustrates the prevailing challenge of deriving robust constraints on this quantity from paleoclimate proxies. In particular, the response of the land carbon cycle to volcanic forcing shows fundamental differences between different models. In CESM the tropical land dictates the response to volcanoes, with a distinct behavior for large and moderate eruptions. Under anthropogenic emissions, global land and ocean carbon uptake rates emerge from the envelope of interannual natural variability by about year 1947 and 1877, respectively, as simulated for the last millennium.

APA, Harvard, Vancouver, ISO, and other styles

34

Lehner, F., F. Joos, C. C. Raible, J. Mignot, A. Born, K. M. Keller, and T. F. Stocker. "Climate and carbon cycle dynamics in a CESM simulation from 850–2100 CE." Earth System Dynamics Discussions 6, no. 1 (February 26, 2015): 351–406. http://dx.doi.org/10.5194/esdd-6-351-2015.

Full text

Abstract:

Abstract. Under the protocols of the Paleoclimate and Coupled Modelling Intercomparison Projects a number of simulations were produced that provide a range of potential climate evolutions from the last millennium to the end of the current century. Here, we present the first simulation with the Community Earth System Model (CESM), which includes an interactive carbon cycle, that continuously covers the last millennium, the historical period, and the twenty-first century. Besides state-of-the-art forcing reconstructions, we apply a modified reconstruction of total solar irradiance to shed light on the issue of forcing uncertainty in the context of the last millennium. Nevertheless, we find that structural uncertainties between different models can still dominate over forcing uncertainty for quantities such as hemispheric temperatures or the land and ocean carbon cycle response. Comparing with other model simulations we find forced decadal-scale variability to occur mainly after volcanic eruptions, while during other periods internal variability masks potentially forced signals and calls for larger ensembles in paleoclimate modeling studies. At the same time, we fail to attribute millennial temperature trends to orbital forcing, as has been suggested recently. The climate-carbon cycle sensitivity in CESM during the last millennium is estimated to be about 1.3 ppm °C−1. However, the dependence of this sensitivity on the exact time period and scale illustrates the prevailing challenge of deriving robust constrains on this quantity from paleoclimate proxies. In particular, the response of the land carbon cycle to volcanic forcing shows fundamental differences between different models. In CESM the tropical land dictates the response to volcanoes with a distinct behavior for large and moderate eruptions. Under anthropogenic emissions, global land and ocean carbon uptake rates emerge from the envelope of interannual natural variability as simulated for the last millennium by about year 1947 and 1877, respectively.

APA, Harvard, Vancouver, ISO, and other styles

35

DONNER, REIK, and ANNETTE WITT. "TEMPORARY DIMENSIONS OF MULTIVARIATE DATA FROM PALEOCLIMATE RECORDS — A NOVEL MEASURE FOR DYNAMIC CHARACTERIZATION OF LONG-TERM CLIMATE CHANGE." International Journal of Bifurcation and Chaos 17, no. 10 (October 2007): 3685–89. http://dx.doi.org/10.1142/s0218127407019573.

Full text

Abstract:

Standard techniques of nonlinear data analysis are difficult to apply to short or insufficiently resolved multivariate time series. We demonstrate that dimension estimation based on the decay of eigenvalues of the covariance matrix yields qualitatively robust characteristics even in the case of very short measurement series. The uncertainty of these characteristics is discussed for both: synthetic data sets and measurement data. We apply this approach to measurements of trace element abundances in a marine sediment core obtained at the East Antarctic coast and discuss the results from a paleoclimate point of view.

APA, Harvard, Vancouver, ISO, and other styles

36

Feulner, Georg. "Climate modelling of mass-extinction events: a review." International Journal of Astrobiology 8, no. 3 (July 2009): 207–12. http://dx.doi.org/10.1017/s1473550409990061.

Full text

Abstract:

AbstractDespite tremendous interest in the topic and decades of research, the origins of the major losses of biodiversity in the history of life on Earth remain elusive. A variety of possible causes for these mass-extinction events have been investigated, including impacts of asteroids or comets, large-scale volcanic eruptions, effects from changes in the distribution of continents caused by plate tectonics, and biological factors, to name but a few. Many of these suggested drivers involve or indeed require changes of Earth's climate, which then affect the biosphere of our planet, causing a global reduction in the diversity of biological species. It can be argued, therefore, that a detailed understanding of these climatic variations and their effects on ecosystems are prerequisites for a solution to the enigma of biological extinctions. Apart from investigations of the paleoclimate data of the time periods of mass extinctions, climate-modelling experiments should be able to shed some light on these dramatic events. Somewhat surprisingly, however, only a few comprehensive modelling studies of the climate changes associated with extinction events have been undertaken. These studies will be reviewed in this paper. Furthermore, the role of modelling in extinction research in general and suggestions for future research are discussed.

APA, Harvard, Vancouver, ISO, and other styles

37

Liu, Shanshan, Dabang Jiang, and Xianmei Lang. "Mid-Holocene drylands: A multi-model analysis using Paleoclimate Modelling Intercomparison Project Phase III (PMIP3) simulations." Holocene 29, no. 9 (June 12, 2019): 1425–38. http://dx.doi.org/10.1177/0959683619854512.

Full text

Abstract:

This study examines changes in aridity levels during the mid-Holocene (approximately 6000 cal. yr ago) using multi-model simulations from the Paleoclimate Modelling Intercomparison Project Phase III. Overall, there is little difference in the total area of drylands from the preindustrial period; global drylands are 8% wetter than during the preindustrial period as measured by an aridity index; and 16% of preindustrial drylands convert to a wetter climate subtype, double the sum of zones that are replaced by a drier category. Considerable variations are present among regions with major contractions of each dryland subtype from northern Africa to South Asia and the main expansions of arid, semiarid, and dry subhumid climates in southern hemisphere continents. The difference in precipitation is the leading factor of the aforementioned changes. The second factor is the altered potential evapotranspiration as mainly induced by relative humidity, which contributes to additional aridity changes in a same direction as precipitation does. The collective effects of precipitation and relative humidity account for more than 80% of the dryland variations. In comparison, the simulated aridity change is in reasonable agreement with reconstructions, while there are model–data discrepancies for Australia and uncertainties across proxies for southern Africa.

APA, Harvard, Vancouver, ISO, and other styles

38

Ohgaito, R., T. Sueyoshi, A. Abe-Ouchi, T. Hajima, S. Watanabe, H. J. Kim, A. Yamamoto, and M. Kawamiya. "Climate and African precipitation changes in the mid-Holocene simulated using an Earth System Model MIROC-ESM." Climate of the Past Discussions 8, no. 4 (August 9, 2012): 3277–343. http://dx.doi.org/10.5194/cpd-8-3277-2012.

Full text

Abstract:

Abstract. The importance of evaluating models using paleoclimate simulations is becoming more recognized in efforts to improve climate projection. To evaluate an integrated Earth System Model, MIROC-ESM, we performed simulations in time-slice experiments for the mid-Holocene (6000 yr before present, 6 ka) and preindustrial (1850 AD) times under the protocol of the Coupled Model Intercomparison Project 5/Paleoclimate Modelling Intercomparison Project 3. We first overview the simulated global climates by comparing with simulations using a previous version of the MIROC model (MIROC3), which is an atmosphere-ocean coupled general circulation model, and then comprehensively discuss various aspects of climate change with 6 ka forcing. We also discuss the 6 ka African monsoon activity. The 6 ka precipitation change over northern Africa according to MIROC-ESM does not differ dramatically from that obtained with MIROC3, which means that newly developed components such as dynamic vegetation and improvements in the atmospheric processes do not have significant impacts on representing the 6 ka monsoon change suggested by proxy records. Although there is no drastic difference in the African monsoon representation between the two models, there are small but significant differences in the precipitation enhancement in MIROC-ESM, which can be related to the representation of the sea surface temperature rather than the vegetation coupling, at least in MIROC-ESM.

APA, Harvard, Vancouver, ISO, and other styles

39

Stärz, M., G. Lohmann, and G. Knorr. "Dynamic soil feedbacks on the climate of the mid-Holocene and the Last Glacial Maximum." Climate of the Past Discussions 9, no. 3 (May 24, 2013): 2717–70. http://dx.doi.org/10.5194/cpd-9-2717-2013.

Full text

Abstract:

Abstract. State-of-the-art general circulation models (GCMs) are tested and challenged by the ability to reproduce paleoclimate key intervals. In order to account for climate changes associated with soil dynamics we have developed a soil scheme, which is asynchronously coupled to a state-of-the-art atmosphere ocean GCM with dynamic vegetation. We test the scheme for conditions representative of a warmer (mid-Holocene, 6 kyr before present, BP) and colder (Last Glacial Maximum, 21 kyr BP) than pre-industrial climate. The computed change of physical soil properties (i.e. albedo, water storage capacity, and soil texture) for these different climates leads to amplified global climate anomalies. Especially regions like the transition zone of desert/savannah and taiga/tundra, exhibit an increased response as a result of the modified soil treatment. In comparison to earlier studies, the inclusion of the soil feedback pushes our model simulations towards the warmer end in the range of mid-Holocene studies and beyond current estimates of global cooling during the Last Glacial Maximum based on PMIP2 (Paleoclimate Modelling Intercomparison Project 2) studies. The main impact of the interactive soil scheme on the climate response is governed by positive feedbacks, including dynamics of vegetation, snow, sea ice, local water recycling, which might amplify forcing factors ranging from orbital to tectonic timescales.

APA, Harvard, Vancouver, ISO, and other styles

40

Beckett, Anna, Cecile Blanchet, Alexander Brauser, Rebecca Kearney, Celia Martin-Puertas, Ian Matthews, Konstantin Mittelbach, Adrian Palmer, Arne Ramisch, and Achim Brauer. "Tephra data from varved lakes of the Last Glacial–Interglacial Transition: towards a global inventory and better chronologies on the Varved Sediments Database (VARDA)." Earth System Science Data 16, no. 1 (January 24, 2024): 595–604. http://dx.doi.org/10.5194/essd-16-595-2024.

Full text

Abstract:

Abstract. The Varved Sediments Database (VARDA) was launched in 2020 and aimed to establish a community database for annually resolved chronological archives with their associated high-resolution proxy records. This resource would support reproducibility through accessible data for the paleoclimate and modelling communities. In this paper, VARDA has been extended by a dataset of European tephra geochemical data and metadata to enable the synchronisation of varve records during the Last Glacial–Interglacial Transition (LGIT; here defined as 25 to 8 ka; Beckett et al., 2022). Geochemical data from 49 known individual tephra layers across 19 lake records have been included, with Lago di Grande Monticchio being the single biggest contributor of geochemical data with 28 tephra layers. The Vedde Ash and Laacher See tephra are the most common layers found in six different records. This highlights the potential of refining the absolute age estimates for these tephra layers using varve chronologies and for synchronising regional paleoclimate archives. This is the first stage in a 5-year plan funded by the Past Global Changes (PAGES) Data Stewardship Scholarship to incorporate a global dataset of tephra geochemical data into varve records. Further stages of this project will focus on different regions and timescales. Data collated for this project are available open access at https://doi.org/10.5880/fidgeo.2023.015 (Beckett et al., 2022).

APA, Harvard, Vancouver, ISO, and other styles

41

Wang, Chun-Jing, and Ji-Zhong Wan. "Historical and contemporary climate legacy of the large-scale distributional patterns of plant richness across different taxonomic levels: An assessment of protected areas in China." Botanical Sciences 97, no. 3 (September 1, 2019): 323. http://dx.doi.org/10.17129/botsci.2211.

Full text

Abstract:

Background: Historical and contemporary climates may shape the distributional patterns of plant species richness across different scales. However, few studies have focused on the effects of historical and contemporary climate changes on the distributional patterns of plant richness in Chinese protected areas across different taxonomic levels.Hypotheses: Historical and contemporary climates can have an important legacy effect on the large-scale distributional patterns of plant richness across different taxonomic levels.Studied species: Vascular plants.Study site: China.Method: We used data on plant richness at the family, genus, and species levels from Chinese protected areas and applied regression modelling to explore the relationships between climate change and plant richness among vascular, fern, seed, gymnosperm, and angiosperm plants based on paleoclimate (Last Glacial Maximum; LGM, ca. 22,000 years ago) and contemporary climate data.Results: The large-scale distributional patterns of plant richness could be predicted across different taxonomic levels on the basis of paleoclimate and contemporary climate data. Specifically, historical and contemporary climate variables were found to better correlate with fern plant richness than seed plant richness. For seed plants, the explanatory power of historical and contemporary climate variables was found to be stronger for the richness of gymnosperms than for the richness of angiosperms.Conclusions: The distributional pattern of plant richness could be predicted across different taxonomic levels after including paleoclimate (LGM, ca. 22,000 years ago) and contemporary climate data from China. Our study could support the effectiveness of the management of protected areas in China.

APA, Harvard, Vancouver, ISO, and other styles

42

Tipton, John R., Mevin B. Hooten, Connor Nolan, Robert K. Booth, and Jason McLachlan. "Predicting paleoclimate from compositional data using multivariate Gaussian process inverse prediction." Annals of Applied Statistics 13, no. 4 (December 2019): 2363–88. http://dx.doi.org/10.1214/19-aoas1281.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

NIU, LU, GERRIT LOHMANN, SEBASTIAN HINCK, EVAN J. GOWAN, and UTA KREBS-KANZOW. "The sensitivity of Northern Hemisphere ice sheets to atmospheric forcing during the last glacial cycle using PMIP3 models." Journal of Glaciology 65, no. 252 (July 3, 2019): 645–61. http://dx.doi.org/10.1017/jog.2019.42.

Full text

Abstract:

ABSTRACTThe evolution of Northern Hemisphere ice sheets through the last glacial cycle is simulated with the glacial index method by using the climate forcing from one General Circulation Model, COSMOS. By comparing the simulated results to geological reconstructions, we first show that the modelled climate is capable of capturing the main features of the ice-sheet evolution. However, large deviations exist, likely due to the absence of nonlinear interactions between ice sheet and other climate components. The model uncertainties of the climate forcing are examined using the output from nine climate models from the Paleoclimate Modelling Intercomparison Project Phase III. The results show a large variability in simulated ice sheets between the different models. We find that the ice-sheet extent pattern resembles summer surface air temperature pattern at the Last Glacial Maximum, confirming the dominant role of surface ablation process for high-latitude Northern Hemisphere ice sheets. This study shows the importance of the upper boundary condition for ice-sheet modelling, and implies that careful constraints on climate output is essential for simulating realistic glacial Northern Hemisphere ice sheets.

APA, Harvard, Vancouver, ISO, and other styles

44

Braconnot, P. "Mid-Holocene and Last Glacial Maximum African monsoon changes as simulated within the Paleoclimate Modelling Intercomparison Project." Global and Planetary Change 26, no. 1-3 (November 2000): 51–66. http://dx.doi.org/10.1016/s0921-8181(00)00033-3.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Ohgaito, Rumi, Akitomo Yamamoto, Tomohiro Hajima, Ryouta O'ishi, Manabu Abe, Hiroaki Tatebe, Ayako Abe-Ouchi, and Michio Kawamiya. "PMIP4 experiments using MIROC-ES2L Earth system model." Geoscientific Model Development 14, no. 2 (March 2, 2021): 1195–217. http://dx.doi.org/10.5194/gmd-14-1195-2021.

Full text

Abstract:

Abstract. Following the protocol of the fourth phase of the Paleoclimate Modelling Intercomparison Project (PMIP4), we performed numerical experiments targeting distinctive past time periods using the Model for Interdisciplinary Research on Climate, Earth System version 2 for Long-term simulations (MIROC-ES2L), which is an Earth system model. Setup and basic performance of the experiments are presented. The Last Glacial Maximum was one of the most extreme climate states during the Quaternary and conducting numerical modeling experiments of this period has long been a challenge for the paleoclimate community. We conducted a Last Glacial Maximum experiment with a long spin-up of nearly 9000 years. Globally, there was reasonable agreement between the anomalies relative to the present day derived from model climatology and those derived from proxy data archives, while some regional discrepancies remained. By changing orbital and greenhouse gas forcings, we conducted experiments for two interglacial periods: 6000 and 127 000 years before present. Model anomalies relative to the present day were qualitatively consistent with variations in solar forcing. However, anomalies in the model were smaller than those derived from proxy data archives, suggesting that processes that play a role in past interglacial climates remain lacking in this state-of-the-art model. We conducted transient simulations from 850 to 1850 CE and from 1850 to 2014 CE. Cooling in the model indicated a clear response to huge volcanic eruptions, consistent with paleo-proxy data. The contrast between cooling during the Little Ice Age and warming during the 20th to 21st centuries was represented well at the multidecadal timescale.

APA, Harvard, Vancouver, ISO, and other styles

46

Zheng, Weipeng, Yongqiang Yu, Yihua Luan, Shuwen Zhao, Bian He, Li Dong, Mirong Song, Pengfei Lin, and Hailong Liu. "CAS-FGOALS Datasets for the Two Interglacial Epochs of the Holocene and the Last Interglacial in PMIP4." Advances in Atmospheric Sciences 37, no. 10 (July 10, 2020): 1034–44. http://dx.doi.org/10.1007/s00376-020-9290-8.

Full text

Abstract:

Abstract Two versions of the Chinese Academy of Sciences Flexible Global Ocean-Atmosphere-Land System model (CAS-FGOALS), version f3-L and g3, are used to simulate the two interglacial epochs of the mid-Holocene and the Last Interglacial in phase 4 of the Paleoclimate Modelling Intercomparison Project (PMIP4), which aims to study the impact of changes in orbital parameters on the Earth’s climate. Following the PMIP4 experimental protocols, four simulations for the mid-Holocene and two simulations for the Last Interglacial have been completed, and all the data, including monthly and daily outputs for the atmospheric, oceanic, land and sea-ice components, have been released on the Earth System Grid Federation (ESGF) node. These datasets contribute to PMIP4 and CMIP6 (phase 6 of the Coupled Model Intercomparison Project) by providing the variables necessary for the two interglacial periods. In this paper, the basic information of the CAS-FGOALS models and the protocols for the two interglacials are briefly described, and the datasets are validated using proxy records. Results suggest that the CAS-FGOALS models capture the large-scale changes in the climate system in response to changes in solar insolation during the interglacial epochs, including warming in mid-to-high latitudes, changes in the hydrological cycle, the seasonal variation in the extent of sea ice, and the damping of interannual variabilities in the tropical Pacific. Meanwhile, disagreements within and between the models and the proxy data are also presented. These datasets will help the modeling and the proxy data communities with a better understanding of model performance and biases in paleoclimate simulations.

APA, Harvard, Vancouver, ISO, and other styles

47

Marshall, Shawn J., Lev Tarasov, Garry K. C. Clarke, and W. Richard Peltier. "Glaciological reconstruction of the Laurentide Ice Sheet: physical processes and modelling challenges." Canadian Journal of Earth Sciences 37, no. 5 (May 1, 2000): 769–93. http://dx.doi.org/10.1139/e99-113.

Full text

Abstract:

Current understanding of Pleistocene ice-sheet history is based on collective inferences from three separate avenues of study: (1) the geologic and paleoceanographic records, (2) the isostatic record, and (3) the behaviour of contemporary glaciers and ice sheets. The geologic record provides good constraint on the areal extent of former ice sheets, while isostatic deflection patterns provide important information about late-glacial ice-sheet thickness. The picture emerging from geologic and isostatic deductions is suggestive of a thin and mobile Laurentide Ice Sheet relative to present-day Greenland and Antarctica. We model Laurentide Ice Sheet evolution through a glacial cycle to explore the glaciological mechanisms that are required to replicate the geologic and isostatic evidence. A number of glaciological processes important to the ice-sheet evolution are not fully understood, including marine-based ice dynamics, iceberg calving, rheologic properties of ice, and basal flow dynamics. We present a spectrum of glacial cycle simulations with different treatments of poorly constrained physical processes. We conclude that glaciological model reconstructions can only be reconciled with the late-glacial geologic record of a thin, low-sloping Laurentide Ice Sheet by invoking (1) extremely deformable ice, (2) widespread basal flow, or (3) paleoclimate-ice-sheet fluctuations which give last glacial maximum ice sheets that are far from equilibrium.

APA, Harvard, Vancouver, ISO, and other styles

48

van Bellen, Simon, Michelle Garneau, Andy Baird, Marc-André Bourgault, and Anne Quillet. "Exploring pathways to late Holocene increased surface wetness in subarctic peatlands of eastern Canada." Quaternary Research 90, no. 1 (May 17, 2018): 83–95. http://dx.doi.org/10.1017/qua.2018.34.

Full text

Abstract:

AbstractThe poor fens of the Laforge region, northeastern Canada, have developed under subarctic conditions. They are characterized by a microtopography of large pools and low, narrow strings. Paleorecords suggest some of these systems were once ombrotrophic and relatively dry. Taking account of their current bioclimatic position, we aimed to explore the possible pathways towards the current wet state, a process referred to as “aqualysis”. We combined paleoecological methods applied to a peat core with conceptual modelling to identify factors that might plausibly explain aqualysis. Reconstructions showed the Abeille peatland became minerotrophic with high water tables between 2400 and 2100 cal yr BP. Conceptual modelling, supported by simulations using the numerical DigiBog model, allowed us to identify the effects of cooling and increased precipitation on productivity, decay, peat hydraulic conductivity and vertical peat accumulation. Both cooling and increased precipitation were required for aqualysis to occur and for wet surface conditions to persist to the present day. Increased recharge from the catchment, which also restricted drainage from the peatland center laterally, was likely critical for the development of minerotrophic conditions. The scenario of cooling and wetting in these peatlands is supported by available paleoclimate records for eastern Canada.

APA, Harvard, Vancouver, ISO, and other styles

49

Zhou, Shangrong, Le Tao, Yun Su, Yue Sui, and Zhongshi Zhang. "Documented and Simulated Warm Extremes during the Last 600 Years over Monsoonal China." Atmosphere 12, no. 3 (March 9, 2021): 362. http://dx.doi.org/10.3390/atmos12030362.

Full text

Abstract:

In this study, we present an analysis of warm extremes over monsoonal China (21–45° N, 106–124° E) during the last 600 years based on Chinese historical documents and simulations from the Paleoclimate Modelling Intercomparison Project Phase 3 (PMIP3) and the Coupled Model Intercomparison Project Phase 5 (CMIP5). The Chinese historical documents indicate that extreme warm records become more frequent after ~1650 CE in North China and ~1850 CE in the Yangtze River Valley. Our analyses of two threshold extreme temperature indices also illustrate that warm extremes have become more frequent since the 17th century in North China and the mid-19th century in Yangtze River Valley in good agreement with the changes in warm extremes revealed in the historical documents. This agreement suggests potential mechanisms behind the shift of periods, which should be further investigated in the future.

APA, Harvard, Vancouver, ISO, and other styles

50

Sun, Jimin, Wenjiao Xiao, Brian F. Windley, and Yongyun Hu. "Editorial preface to special issue: Cenozoic tectonics and paleoclimate in Inner Asia: From case studies to climatic modelling." Palaeogeography, Palaeoclimatology, Palaeoecology 622 (July 2023): 111616. http://dx.doi.org/10.1016/j.palaeo.2023.111616.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Paleoclimate modelling'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles