Contribution of sea ice albedo and insulation effects to Arctic amplification in the EC-Earth Pliocene simulation

Zheng, Jianqiu; Zhang, Qiong; Li, Qiang; Cai, Ming

doi:10.5194/cp-15-291-2019

Cited by 33 publications

(31 citation statements)

References 52 publications

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“…Since there is very little sea ice, more heat can be released, explaining the higher SAT in the Arctic during September to November. This was also seen in the study by Zheng et al (2019). The Hudson Bay shows a large temperature reduction during winter because it has been replaced by land which cannot stabilise the surface air temperature as much as water can (Hunter et al, 2019).…”

Section: Surface Air Temperaturesupporting

confidence: 68%

Pliocene Model Intercomparison Project (PlioMIP2) simulations using the Model for Interdisciplinary Research on Climate (MIROC4m)

Chan

Abe‐Ouchi

2020

Clim. Past

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Abstract. The second phase of the Pliocene Model Intercomparison Project (PlioMIP2) has attracted many climate modelling groups in its continuing efforts to better understand the climate of the mid-Piacenzian warm period (mPWP) when atmospheric CO2 was last closest to present-day levels. Like the first phase, PlioMIP1, it is an internationally coordinated initiative that allows for a systematic comparison of various models in a similar manner to the Paleoclimate Modelling Intercomparison Project (PMIP). Model intercomparison and model–data comparison now focus specifically on the interglacial at marine isotope stage KM5c (3.205 Ma), and experimental design is not only based on new boundary conditions but includes various sensitivity experiments. In this study, we present results from long-term model integrations using the MIROC4m (Model for Interdisciplinary Research on Climate) atmosphere–ocean coupled general circulation model, developed at the institutes CCSR, NIES and FRCGC in Japan. The core experiment, with CO2 levels set to 400 ppm, shows a warming of 3.1 ∘C compared to the pre-industrial period, with two-thirds of the warming being attributed to the increase in CO2. Although this level of warming is less than that in the equivalent PlioMIP1 experiment, there is slightly better agreement with proxy sea surface temperature (SST) data at PRISM3 (PRISM – Pliocene Research Interpretation and Synoptic Mapping) locations, especially in the northern North Atlantic where there were large model–data discrepancies in PlioMIP1. Similar spatial changes in precipitation and sea ice are seen and the Arctic remains ice-free in the summer in the core experiments of both phases. Comparisons with both the proxy SST data and proxy surface air temperature data from paleobotanical sites indicate a weaker polar amplification in model results. Unlike PlioMIP1, the Atlantic Meridional Overturning Circulation (AMOC) is now stronger than that of the pre-industrial period, even though increasing CO2 tends to weaken it. This stronger AMOC is a consequence of a closed Bering Strait in the PlioMIP2 paleogeography. Also, when present-day boundary conditions are replaced by those of the Pliocene, the dependency of the AMOC strength on CO2 is significantly weakened. Sensitivity tests show that lower values of CO2 give a global SST which is overall more consistent with the PRISM3 SST field presented in PlioMIP1, while SSTs at many of the PRISM4 sites are still too high to be reconciled with any of the model results. On the other hand, tropical Pacific SST in the core experiment agrees well with more recent proxy data, which suggested that PRISM3 SST there was overestimated. Future availability of climate reconstructions from proxy data will continue to help evaluate model results. The inclusion of dynamical vegetation and the effects of all possible extreme orbital configurations outside KM5c should be considered in future experiments using MIROC4m for the mPWP.

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Section: Surface Air Temperaturesupporting

confidence: 68%

Pliocene Model Intercomparison Project (PlioMIP2) simulations using the Model for Interdisciplinary Research on Climate (MIROC4m)

Chan

Abe‐Ouchi

2020

Clim. Past

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“…In marine and lacustrine sediments, bacterial brGDGTs were thought to originate predominantly from continental soil erosion arriving in the sediments through terrestrial runoff. More recent studies, however, have indicated that aquatically produced brGDGTs could be affecting the distribution of the sedimentary brGDGTs and thus the temperature estimates based upon them (Warden et al, 2016;Zell et al, 2013;Zhu et al, 2011). Since the discovery that sedimentary brGDGTs can have varying sources, different calibrations have been developed depending on the origin of the brGDGTs, i.e., soil calibration (De Jonge et al, 2014), peat calibration (Naafs et al, 2017) and aquatic calibrations (i.e., Foster et al, 2016;Pearson et al, 2011;Russell et al, 2018).…”

Section: Provenance Of Branched Gdgtsmentioning

confidence: 99%

“…Paleoclimate records from the Arctic indicate that the change in Arctic summer temperatures during past global warm periods was 3-4 times larger than global temperature change (Miller et al, 2010). While earth system models (ESMs) have been able to provide fairly accurate predictions of the modern amplification of Arctic temperatures hitherto observed for some time (Marshall et al, 2014), they have only recently implemented mechanisms that simulate Arctic amplification of temperature for past warm periods such as the Pliocene (2.6-5.3) with a convincing pattern of seasonality (Zheng et al, 2019). The success of earlier models at capturing modern warming, contrasted with the additions needed to simulate the Pliocene Arctic temperatures, suggest that the array of fast and slow feedback mechanisms have not fully manifested themselves for the modern Arctic, and perhaps there are still further feedback mechanisms we are yet to understand and implement in climate models.…”

Section: Introductionmentioning

confidence: 99%

Evidence for fire in the Pliocene Arctic in response to amplified temperature

et al. 2019

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The mid-Pliocene is a valuable time interval for investigating equilibrium climate at current atmospheric CO 2 concentrations because atmospheric CO 2 concentrations are thought to have been comparable to the current day and yet the climate and distribution of ecosystems were quite different. One intriguing, but not fully understood, feature of the early to mid-Pliocene climate is the amplified Arctic temperature response and its impact on Arctic ecosystems. Only the most recent models appear to correctly estimate the degree of warming in the Pliocene Arctic and validation of the currently proposed feedbacks is limited by scarce terrestrial records of climate and environment. Here we reconstruct the summer temperature and fire regime from a subfossil fenpeat deposit on west-central Ellesmere Island, Canada, that has been chronologically constrained using cosmogenic nuclide burial dating to 3.9 + 1.5/ − 0.5 Ma.The estimate for average mean summer temperature is 15.4 ± 0.8 • C using specific bacterial membrane lipids, i.e., branched glycerol dialkyl glycerol tetraethers. This is above the proposed threshold that predicts a substantial increase in wildfire in the modern high latitudes. Macro-charcoal was present in all samples from this Pliocene section with notably higher charcoal concentration in the upper part of the sequence. This change in charcoal was synchronous with a change in vegetation that included an increase in abundance of fire-promoting Pinus and Picea. Paleo-vegetation reconstructions are consistent with warm summer temperatures, relatively low summer precipitation and an incidence of fire comparable to fire-adapted boreal forests of North America and central Siberia.To our knowledge, this site provides the northernmost evidence of fire during the Pliocene. It suggests that ecosystem productivity was greater than in the present day, providing fuel for wildfires, and that the climate was conducive to the ignition of fire during this period. The results reveal that interactions between paleo-vegetation and paleoclimate were mediated by fire in the High Arctic during the Pliocene, even though CO 2 concentrations were similar to modern values.Published by Copernicus Publications on behalf of the European Geosciences Union.

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“…As a practical diagnostic tool to analyse the role of various forcing and 152 feedback, CFRAM has been used widely in climate change research on 153 studying surface climate change (Taylor et al, 2013;Song and Zhang, 2014;154 Hu et al, 2017;Zheng et al, 2019). 155 156 This method has been applied to the middle atmosphere climate sensitivity 157 study as well (Zhu et al, 2016).…”

Section: ) 143 144mentioning

confidence: 99%

Quantifying climate feedbacks in the middle atmosphere using WACCM

Kuilman

Zhang

Cai

et al. 2020

Preprint

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Abstract. The importance of feedback processes in the middle atmosphere for surface and tropospheric climate is increasingly realized. To better understand feedback processes in response to a doubling of CO2 we use the climate feedback response analysis method (CFRAM). We examine the middle atmosphere response to CO2 doubling with respect to the pre-industrial state in the Whole Atmosphere Community Climate Model (WACCM). Globally, the simulated temperature decrease between 200 and 0.01 hPa (~ 12–80 km) is found to be −5.2 K in July and −5.5 K in January in WACCM. The CFRAM calculations show that the direct forcing of CO2 alone would lead to an even stronger cooling of approximately 9 K in the middle atmosphere in both July and January. This cooling is being mitigated by the combined effect of the different feedback processes. The contribution from the ozone feedback causes a warming of approximately 1.5 K, mitigating the cooling due to changes in CO2. Changes in CO2 also lead to changes in the middle atmosphere dynamics. The changes in dynamics play a large role locally, especially above 0.1 hPa. Other feedback processes, which are known to be important in the tropospheric and surface climate, such as the water vapor, albedo and cloud feedbacks are of minor importance in the middle atmosphere,although some effects are seen in the stratosphere, mainly through the responses to sea surface temperature and sea ice changes. It should be noted that there is a relatively large error term associated with the current method in the middle atmosphere, which can be explained by the linearization in the method.

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Contribution of sea ice albedo and insulation effects to Arctic amplification in the EC-Earth Pliocene simulation

Cited by 33 publications

References 52 publications

Pliocene Model Intercomparison Project (PlioMIP2) simulations using the Model for Interdisciplinary Research on Climate (MIROC4m)

Pliocene Model Intercomparison Project (PlioMIP2) simulations using the Model for Interdisciplinary Research on Climate (MIROC4m)

Evidence for fire in the Pliocene Arctic in response to amplified temperature

Quantifying climate feedbacks in the middle atmosphere using WACCM

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