A multi-model assessment of last interglacial temperatures

Abstract. The Last Interglaciation (∼130 to 116 ka) is a time period with a strong astronomically-induced seasonal forcing of insolation compared to modern. Proxy records indicate a significantly different climate to that of the modern, in particular Arctic summer warming and higher eustatic sea level. Because the forcings are relatively well constrained, it provides an opportunity to test numerical models which are used for future climate prediction. In this paper, we compile a set of climate model simulations of the early Last Interglaciation (130 to 125 ka), encompassing a range of model complexity. We compare the models to each other, and to a recently published compilation of Last Interglacial temperature estimates. We show that the annual mean response of the models is rather small, with no clear signal in many regions. However, the seasonal response is more robust, and there is significant agreement amongst models as to the regions of warming vs. cooling. However, the quantitative agreement of the models with data is poor, with the models in general underestimating the magnitude of response seen in the proxies. Taking possible seasonal biases in the proxies into account improves the agreement marginally, but the agreement is still far from perfect. However, a lack of uncertainty estimates in the data does not allow us to draw firm conclusions. Instead, this paper points to several ways in which both modelling and data could be improved, to allow a more robust model-data comparison.

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A multi-model assessment of last interglacial temperatures

Climate of the Past ◽

10.5194/cp-9-699-2013 ◽

2013 ◽

Vol 9 (2) ◽

pp. 699-717 ◽

Cited By ~ 103

Author(s):

D. J. Lunt ◽

A. Abe-Ouchi ◽

P. Bakker ◽

A. Berger ◽

P. Braconnot ◽

...

Keyword(s):

Climate Model ◽

Numerical Models ◽

Quantitative Agreement ◽

Model Assessment ◽

Last Interglacial ◽

Model Simulations ◽

Proxy Records ◽

Robust Model ◽

Uncertainty Estimates ◽

Climate Model Simulations

Abstract. The last interglaciation (~130 to 116 ka) is a time period with a strong astronomically induced seasonal forcing of insolation compared to the present. Proxy records indicate a significantly different climate to that of the modern, in particular Arctic summer warming and higher eustatic sea level. Because the forcings are relatively well constrained, it provides an opportunity to test numerical models which are used for future climate prediction. In this paper we compile a set of climate model simulations of the early last interglaciation (130 to 125 ka), encompassing a range of model complexities. We compare the simulations to each other and to a recently published compilation of last interglacial temperature estimates. We show that the annual mean response of the models is rather small, with no clear signal in many regions. However, the seasonal response is more robust, and there is significant agreement amongst models as to the regions of warming vs cooling. However, the quantitative agreement of the model simulations with data is poor, with the models in general underestimating the magnitude of response seen in the proxies. Taking possible seasonal biases in the proxies into account improves the agreement, but only marginally. However, a lack of uncertainty estimates in the data does not allow us to draw firm conclusions. Instead, this paper points to several ways in which both modelling and data could be improved, to allow a more robust model–data comparison.

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Teleconnections and relationship between ENSO and SAM in reconstructions and models over the past millennium

10.5194/cp-2019-110 ◽

2019 ◽

Author(s):

Christoph Dätwyler ◽

Martin Grosjean ◽

Nathan J. Steiger ◽

Raphael Neukom

Keyword(s):

Climate Model ◽

Southern Oscillation ◽

Negative Temperature ◽

Internal Variability ◽

Southern Annular Mode ◽

Teleconnection Patterns ◽

Modes Of Variability ◽

Proxy Records ◽

Climate Model Simulations ◽

Instrumental Records

Abstract. The climate of the Southern Hemisphere (SH) is strongly influenced by variations in the El Niño-Southern Oscillation (ENSO) and the Southern Annular Mode (SAM). Due to the temporally very limited instrumental records in most parts of the SH, very little is known about the relationship between these two key modes of variability and its stability over time. Here, we use proxy-based reconstructions and climate model simulations to quantify changes in tropical-extratropical SH teleconnections as represented by the correlation between the ENSO and SAM indices. Reconstructions indicate mostly negative correlations back to around 1400 CE confirming the pattern seen in the instrumental record over the last few decades. An ensemble of last millennium simulations of the model CESM1 confirms this pattern with very stable ensemble mean correlations around −0.3. Individual forced simulations, the pre-industrial control run and the proxy-based reconstructions indicate intermittent periods of positive correlations and particularly strong negative correlations. The fluctuations of the ENSO-SAM correlations are not significantly related to solar nor volcanic forcing in both proxy and model data, indicating that they are driven by internal variability in the climate system. Pseudoproxy experiments indicate that the currently available proxy records are able to reproduce the tropical-extratropical teleconnection patterns back to around 1600 CE. We analyse the spatial temperature and sea level pressure patterns during periods of positive and particularly strong negative teleconnections in the CESM model. Results indicate no consistent pattern during periods where the ENSO-SAM teleconnection changes its sign. However, periods of very strong negative SH teleconnections are associated with negative temperature anomalies across large fractions of the extra-tropical Pacific and a strengthening of the Aleutian Low.

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Satellite Observations for CMIP5: The Genesis of Obs4MIPs

Bulletin of the American Meteorological Society ◽

10.1175/bams-d-12-00204.1 ◽

2014 ◽

Vol 95 (9) ◽

pp. 1329-1334 ◽

Cited By ~ 45

Author(s):

Joao Teixeira ◽

Duane Waliser ◽

Robert Ferraro ◽

Peter Gleckler ◽

Tsengdar Lee ◽

...

Keyword(s):

Observational Data ◽

Climate Models ◽

Climate Model ◽

Coupled Model ◽

Climate Science ◽

Satellite Observations ◽

Model Intercomparison ◽

Uncertainty Estimates ◽

Science Community ◽

Climate Model Simulations

The objective of the Observations for Model Intercomparison Projects (Obs4MIPs) is to provide observational data to the climate science community, which is analogous (in terms of variables, temporal and spatial frequency, and periods) to output from the 5th phase of the World Climate Research Programme's (WCRP) Coupled Model Intercomparison Project (CMIP5) climate model simulations. The essential aspect of the Obs4MIPs methodology is that it strictly follows the CMIP5 protocol document when selecting the observational datasets. Obs4MIPs also provides documentation that describes aspects of the observational data (e.g., data origin, instrument overview, uncertainty estimates) that are of particular relevance to scientists involved in climate model evaluation and analysis. In this paper, we focus on the activities related to the initial set of satellite observations, which are being carried out in close coordination with CMIP5 and directly engage NASA's observational (e.g., mission and instrument) science teams. Having launched Obs4MIPs with these datasets, a broader effort is also briefly discussed, striving to engage other agencies and experts who maintain datasets, including reanalysis, which can be directly used to evaluate climate models. Different strategies for using satellite observations to evaluate climate models are also briefly summarized.

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Empirical estimate of the signal content of Holocene temperature proxy records

10.5194/cp-2018-154 ◽

2018 ◽

Author(s):

Maria Reschke ◽

Kira Rehfeld ◽

Thomas Laepple

Keyword(s):

Time Series ◽

Climate Models ◽

Climate Model ◽

Time Series Data ◽

Series Data ◽

Past Climate ◽

Proxy Records ◽

Model Time Series ◽

Climate Model Simulations ◽

Temperature Proxy

Abstract. Proxy records from climate archives provide evidence about past climate changes, but the recorded signal is affected by non-climate related effects as well as time uncertainty. As proxy based climate reconstructions are frequently used to test climate models and to quantitatively infer past climate, we need to improve our understanding of the proxy records’ signal content as well as the uncertainties involved. In this study, we empirically estimate signal-to-noise ratios (SNRs) of temperature proxy records used in global compilations of the mid to late Holocene. This is achieved through a comparison of proxy time series from close-by sites of three compilations and model time series data at the proxy sites from two transient Holocene climate model simulations. In all comparisons, we found the mean correlations of the proxy time series on centennial to millennial time scales to be rather low (R

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Multiscale combination of climate model simulations and proxy records over the last millennium

Theoretical and Applied Climatology ◽

10.1007/s00704-017-2119-4 ◽

2017 ◽

Vol 132 (3-4) ◽

pp. 763-777

Author(s):

Xin Chen ◽

Pei Xing ◽

Yong Luo ◽

Suping Nie ◽

Zongci Zhao ◽

...

Keyword(s):

Climate Model ◽

Last Millennium ◽

Model Simulations ◽

Proxy Records ◽

Climate Model Simulations

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Impact of meltwater on high-latitude early Last Interglacial climate

Climate of the Past ◽

10.5194/cp-12-1919-2016 ◽

2016 ◽

Vol 12 (9) ◽

pp. 1919-1932 ◽

Cited By ~ 14

Author(s):

Emma J. Stone ◽

Emilie Capron ◽

Daniel J. Lunt ◽

Antony J. Payne ◽

Joy S. Singarayer ◽

...

Keyword(s):

Southern Ocean ◽

North Atlantic ◽

Climate Model ◽

Model Data ◽

Last Interglacial ◽

Model Simulations ◽

The North ◽

Freshwater Forcing ◽

The North Atlantic ◽

Climate Model Simulations

Abstract. Recent data compilations of the early Last Interglacial period have indicated a bipolar temperature response at 130 ka, with colder-than-present temperatures in the North Atlantic and warmer-than-present temperatures in the Southern Ocean and over Antarctica. However, climate model simulations of this period have been unable to reproduce this response, when only orbital and greenhouse gas forcings are considered in a climate model framework. Using a full-complexity general circulation model we perform climate model simulations representative of 130 ka conditions which include a magnitude of freshwater forcing derived from data at this time. We show that this meltwater from the remnant Northern Hemisphere ice sheets during the glacial–interglacial transition produces a modelled climate response similar to the observed colder-than-present temperatures in the North Atlantic at 130 ka and also results in warmer-than-present temperatures in the Southern Ocean via the bipolar seesaw mechanism. Further simulations in which the West Antarctic Ice Sheet is also removed lead to warming in East Antarctica and the Southern Ocean but do not appreciably improve the model–data comparison. This integrated model–data approach provides evidence that Northern Hemisphere freshwater forcing is an important player in the evolution of early Last Interglacial climate.

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Ecological and hydroclimate responses to strengthening of the Hadley circulation in South America during the Late Miocene cooling

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1810721116 ◽

2019 ◽

Vol 116 (20) ◽

pp. 9747-9752 ◽

Cited By ~ 7

Author(s):

Barbara Carrapa ◽

Mark Clementz ◽

Ran Feng

Keyword(s):

South America ◽

Late Miocene ◽

Climate Model ◽

Hadley Circulation ◽

C4 Plant ◽

General Increase ◽

Proxy Records ◽

Pedogenic Carbonates ◽

Grassland Ecosystems ◽

Climate Model Simulations

Near-modern ecosystems were established as a result of rapid ecological adaptation and climate change in the Late Miocene. On land, Late Miocene aridification spread in tandem with expansion of open habitats including C4 grassland ecosystems. Proxy records for the central Andes spanning the Late Miocene cooling (LMC) show the reorganization of subtropical ecosystems and hydroclimate in South America between 15 and 35°S. Continental pedogenic carbonates preserved in Neogene basins record a general increase of δ18O and δ13C values from pre-LMC to post-LMC, most robustly occurring in the subtropics (25 to 30°S), suggesting aridification and a shift toward a more C4-plant-dominated ecosystem. These changes are closely tied to the enhancement of the Hadley circulation and moisture divergence away from the subtropics toward the Intertropical Convergence Zone as revealed by climate model simulations with prescribed sea-surface temperatures (SSTs) reflecting different magnitudes of LMC steepening of equator-to-pole temperature gradient and CO2 decline.

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Changes in the high-latitude Southern Hemisphere through the Eocene–Oligocene transition: a model–data comparison

Climate of the Past ◽

10.5194/cp-16-555-2020 ◽

2020 ◽

Vol 16 (2) ◽

pp. 555-573 ◽

Cited By ~ 2

Author(s):

Alan T. Kennedy-Asser ◽

Daniel J. Lunt ◽

Paul J. Valdes ◽

Jean-Baptiste Ladant ◽

Joost Frieling ◽

...

Keyword(s):

Southern Hemisphere ◽

Climate Model ◽

Drake Passage ◽

Climatic Changes ◽

High Latitudes ◽

Model Simulations ◽

Proxy Records ◽

Before And After ◽

Climate Model Simulations ◽

Atmospheric Pco2

Abstract. The global and regional climate changed dramatically with the expansion of the Antarctic Ice Sheet at the Eocene–Oligocene transition (EOT). These large-scale changes are generally linked to declining atmospheric pCO2 levels and/or changes in Southern Ocean gateways such as the Drake Passage around this time. To better understand the Southern Hemisphere regional climatic changes and the impact of glaciation on the Earth's oceans and atmosphere at the EOT, we compiled a database of 10 ocean and 4 land-surface temperature reconstructions from a range of proxy records and compared this with a series of fully coupled, low-resolution climate model simulations from two models (HadCM3BL and FOAM). Regional patterns in the proxy records of temperature show that cooling across the EOT was less at high latitudes and greater at mid-latitudes. While certain climate model simulations show moderate–good performance at recreating the temperature patterns shown in the data before and after the EOT, in general the model simulations do not capture the absolute latitudinal temperature gradient shown by the data, being too cold, particularly at high latitudes. When taking into account the absolute temperature before and after the EOT, as well as the change in temperature across it, simulations with a closed Drake Passage before and after the EOT or with an opening of the Drake Passage across the EOT perform poorly, whereas simulations with a drop in atmospheric pCO2 in combination with ice growth generally perform better. This provides further support for previous research that changes in atmospheric pCO2 are more likely to have been the driver of the EOT climatic changes, as opposed to the opening of the Drake Passage.

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The future of sea level: More knowledge, more uncertainty

10.5194/egusphere-egu2020-7675 ◽

2020 ◽

Author(s):

Dewi Le Bars ◽

Sybren Drijfhout ◽

Marjolijn Haasnoot

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Climate Model ◽

Numerical Models ◽

Coupled Model ◽

Expert Judgment ◽

Mitigation And Adaptation ◽

Level Information ◽

Climate Model Simulations

Sea level rise is one of the most indisputable effects of global warming with important consequences for current decisions concerning mitigation and adaptation. A few evolutions in the climate and decision making fields have recently increased the concerns of sea level information users about the potential impacts of future sea level. We identify four main evolutions:- Most countries are not on track to reach their Paris agreement emission pledges, making the goal of staying well bellow 2&#186;C less and less attainable.- New climate model simulations from the Coupled Model Inter-comparison Project 6 (CMIP6) have both a higher average climate sensitivity and a larger spread between models compared to CMIP5.- The Greenland and Antarctic ice sheets are melting faster than expected in previous IPCC reports and future projections from a recent structured expert judgment show larger expected melt and more uncertainty than both current numerical models and a previous expert judgment.- Decision makers are more and more interested in events with a large impact and a small probability to build robust infrastructure and design robust long term strategies concerning relocation of coastal communities.While these four evolutions are fundamentally deeply uncertain, to explore their combined effect we build a subjective probabilistic framework that allows to propagate the uncertainty through the different components and obtain sea level rise projections. In this presentation we present this framework, the results and their sensitivity to multiple hypothesis and we discuss implications for different uses and users of sea level rise information.

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Warm Climate States during Last Glacial Cycle with a Multi-Resolution Climate/Ice Sheet Model

10.5194/egusphere-egu2020-8205 ◽

2020 ◽

Author(s):

Paul Gierz ◽

Lars Ackermann ◽

Christian Rodehacke ◽

Uta Krebs-Kanzow ◽

Christian Stepanek ◽

...

Keyword(s):

Climate Model ◽

Ice Sheets ◽

Ice Sheet ◽

Glacial Cycle ◽

Last Interglacial ◽

Sea Levels ◽

The Holocene ◽

Climate Model Simulations ◽

Proxy Reconstructions ◽

Improved Model

Interglacials during the Quaternary represent the youngest climate states in the paleoclimate record that are similar to potential warmer-than-present states during the Anthropocene. In particular, those periods with warmer reconstructed temperatures and/or higher sea levels provide insights into the mechanisms that may be at work now and in the future. To date, climate model simulations of Quaternary Interglacials have been restricted to Atmosphere-Biosphere-Ocean simulations, with static ice sheet geometries from glaciological, geological, and geophysical reconstructions. Simulations including fully interactive ice sheets have not been widely available. Here, we present the first simulations of the PMIP4 timeslices for the Holocene and the Last Interglacial (LIG) with a fully coupled multi-resolution climate/cryosphere model, the AWI-ESM. We compare the simulated snapshots for the Holocene and LIG to simulations to proxy reconstructions, and to runs without dynamic ice sheets to highlight the processes now represented by the improved model. Furthermore, we show various schemes implemented in our model system to represent the ice sheet mass balance, both from surface ablation as well as ocean interaction. We find that both the Holocene and Last Interglacial ice sheets contain a smaller volume of ice compared to present day, with relative sea level equivalent changes of -3% and -7%, respectively.

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