scholarly journals Isolating the Temperature Feedback Loop and Its Effects on Surface Temperature

2016 ◽  
Vol 73 (8) ◽  
pp. 3287-3303 ◽  
Author(s):  
Sergio A. Sejas ◽  
Ming Cai
Keyword(s):  
Surface Temperature ◽  
Feedback Loop ◽  
Temperature Response ◽  
Feedback Loops ◽  
The Arctic ◽  
Response Analysis ◽  
Surface Warming ◽  
Temperature Feedback ◽  
The Tropics ◽  
Temperature Responses

Abstract Climate feedback processes are known to substantially amplify the surface warming response to an increase of greenhouse gases. When the forcing and feedbacks modify the temperature response they trigger temperature feedback loops that amplify the direct temperature changes due to the forcing and nontemperature feedbacks through the thermal–radiative coupling between the atmosphere and surface. This study introduces a new feedback-response analysis method that can isolate and quantify the effects of the temperature feedback loops of individual processes on surface temperature from their corresponding direct surface temperature responses. The authors analyze a 1% yr−1 increase of CO2 simulation of the NCAR CCSM4 at the time of CO2 doubling to illustrate the new method. The Planck sensitivity parameter, which indicates colder regions experience stronger surface temperature responses given the same change in surface energy flux, is the inherent factor that leads to polar warming amplification (PWA). This effect explains the PWA in the Antarctic, while the direct temperature response to the albedo and cloud feedbacks further explains the greater PWA of the Arctic. Temperature feedback loops, particularly the one associated with the albedo feedback, further amplify the Arctic surface warming relative to the tropics. In the tropics, temperature feedback loops associated with the CO2 forcing and water vapor feedback cause most of the surface warming. Overall, the temperature feedback is responsible for most of the surface warming globally, accounting for nearly 76% of the global-mean surface warming. This is 3 times larger than the next largest warming contribution, indicating that the temperature feedback loop is the preeminent contributor to the surface warming.

scholarly journals How Asian aerosols impact regional surface temperatures across the globe

2020 ◽  
Author(s):  
Joonas Merikanto ◽  
Kalle Nordling ◽  
Petri Räisänen ◽  
Jouni Räisänen ◽  
Declan O'Donnell ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Temperature Effects ◽  
Energy Transport ◽  
Temperature Response ◽  
The Arctic ◽  
Anthropogenic Aerosols ◽  
Atmospheric Energy ◽  
Atmospheric Energy Transport ◽  
Temperature Responses ◽  
Global Surface

Abstract. South and East Asian anthropogenic aerosols mostly reside in an air mass extending from the Indian Ocean to the North Pacific. Yet the surface temperature effects of Asian aerosols spread across the whole globe. Here, we remove Asian anthropogenic aerosols from two independent climate models (ECHAM6.1 and NorESM1) using the same representation of aerosols via MACv2-SP (a simple plume implementation of the 2nd version of the Max Planck Institute Aerosol Climatology). We then robustly decompose the global distribution of surface temperature responses into contributions from atmospheric energy flux changes. We find that the horizontal atmospheric energy transport strongly moderates the surface temperature response over the regions where Asian aerosols reside. Atmospheric energy transport and changes in clear-sky longwave radiation redistribute the temperature effects efficiently across the Northern hemisphere, and to a lesser extent also over the Southern hemisphere. The model-mean global surface temperature response to Asian anthropogenic aerosol removal is 0.26 ± 0.04 °C (0.22 ± 0.03 for ECHAM6.1 and 0.30 ± 0.03 °C for NorESM1) of warming. Model-to-model differences in global surface temperature response mainly arise from differences in longwave cloud (0.01 ± 0.01 for ECHAM6.1 and 0.05 ± 0.01 °C for NorESM1) and shortwave cloud (0.03 ± 0.03 for ECHAM6.1 and 0.07 ± 0.02 °C for NorESM1) responses. The differences in cloud responses between the models also dominate the differences in regional temperature responses. In both models, the Northern hemispheric surface warming amplifies towards the Arctic, where the total temperature response is highly seasonal and weakest during the Arctic summer. We estimate that under a strong Asian aerosol mitigation policy tied with strong climate mitigation (Shared Socioeconomic Pathway 1-1.9) the Asian aerosol reductions can add around 8 years' worth of current day global warming during the next few decades.

scholarly journals Local and remote mean and extreme temperature response to regional aerosol emissions reductions

2019 ◽  
Author(s):  
Daniel M. Westervelt ◽  
Nora R. Mascioli ◽  
Arlene M. Fiore ◽  
Andrew J. Conley ◽  
Jean-François Lamarque ◽  
...  
Keyword(s):  
Extreme Temperature ◽  
Temperature Response ◽  
Carbonaceous Aerosol ◽  
The Arctic ◽  
Emissions Reductions ◽  
Aerosol Forcing ◽  
Regional Temperature ◽  
The Tropics ◽  
Aerosol Emissions ◽  
Temperature Responses

Abstract. The climatic implications of regional aerosol and precursor emissions reductions implemented to protect human health are poorly understood. We investigate the mean and extreme temperature response to regional changes in aerosol emissions using three coupled chemistry-climate models: NOAA GFDL-CM3, NCAR-CESM1, and NASA GISS-E2. Our approach contrasts a long present-day control simulation from each model (up to 400 years with perpetual year 2000 or 2005 emissions) with fourteen individual aerosol emissions perturbation simulations (160–240 years each). We perturb emissions of sulfur dioxide (SO2) and/or carbonaceous aerosol within six world regions and assess the statistical significance of mean and extreme temperature responses relative to internal variability determined by the control simulation and across the models. In all models, the global mean surface temperature response (perturbation minus control) to SO2 and/or carbonaceous aerosol is mostly positive (warming), statistically significant, and ranges from +0.17 K (Europe SO2) to −0.06 K (US BC). The warming response to SO2 reductions is strongest in the US and Europe perturbation simulations, both globally and regionally, with Arctic warming up to 1 K due to a removal of European anthropogenic SO2 emissions alone; however, even emissions from regions remote to the Arctic, such as SO2 from India, significantly warm the Arctic by up to 0.5 K. Arctic warming is the most robust response across each model and several aerosol emissions perturbations. The temperature response in the northern hemisphere mid-latitudes is most sensitive to emissions perturbations within that region. In the tropics, however, the temperature response to emissions perturbations is roughly the same in magnitude from emissions perturbations either within or outside of the tropics. We find that climate sensitivity to regional aerosol perturbations ranges from 0.5 to 1.0 K per W m−2 depending on the region and aerosol composition, and is larger than the climate sensitivity to a doubling of CO2 in two of three models. We update previous estimates of Regional Temperature Potential (RTP), a metric for estimating the regional temperature responses to a regional emissions perturbation that can facilitate assessment of climate impacts with integrated assessment models without requiring computationally demanding coupled climate model simulations. These calculations indicate a robust regional response to aerosol forcing within the northern hemisphere mid-latitudes, regardless of where the aerosol forcing is located longitudinally. We show that regional aerosol perturbations can significantly increase extreme temperatures on the regional scale. Except in the Arctic in the summer, extreme temperature responses largely mirror mean temperature responses to regional aerosol perturbations through a shift of the temperature distributions and are mostly dominated by local rather than remote aerosol forcing.

scholarly journals How Asian aerosols impact regional surface temperatures across the globe

2021 ◽  
Vol 21 (8) ◽  
pp. 5865-5881
Author(s):  
Joonas Merikanto ◽  
Kalle Nordling ◽  
Petri Räisänen ◽  
Jouni Räisänen ◽  
Declan O'Donnell ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Temperature Effects ◽  
Energy Transport ◽  
Temperature Response ◽  
The Arctic ◽  
Anthropogenic Aerosols ◽  
Atmospheric Energy ◽  
Atmospheric Energy Transport ◽  
Temperature Responses ◽  
Global Surface

Abstract. South and East Asian anthropogenic aerosols mostly reside in an air mass extending from the Indian Ocean to the North Pacific. Yet the surface temperature effects of Asian aerosols spread across the whole globe. Here, we remove Asian anthropogenic aerosols from two independent climate models (ECHAM6.1 and NorESM1) using the same representation of aerosols via MACv2-SP (a simple plume implementation of the second version of the Max Planck Institute Aerosol Climatology). We then robustly decompose the global distribution of surface temperature responses into contributions from atmospheric energy flux changes. We find that the horizontal atmospheric energy transport strongly moderates the surface temperature response over the regions where Asian aerosols reside. Atmospheric energy transport and changes in clear-sky longwave radiation redistribute the temperature effects efficiently across the Northern Hemisphere and to a lesser extent also over the Southern Hemisphere. The model-mean global surface temperature response to Asian anthropogenic aerosol removal is 0.26±0.04 ∘C (0.22±0.03 for ECHAM6.1 and 0.30±0.03 ∘C for NorESM1) of warming. Model-to-model differences in global surface temperature response mainly arise from differences in longwave cloud (0.01±0.01 for ECHAM6.1 and 0.05±0.01 ∘C for NorESM1) and shortwave cloud (0.03±0.03 for ECHAM6.1 and 0.07±0.02 ∘C for NorESM1) responses. The differences in cloud responses between the models also dominate the differences in regional temperature responses. In both models, the northern-hemispheric surface warming amplifies towards the Arctic, where the total temperature response is highly seasonal and weakest during the Arctic summer. We estimate that under a strong Asian aerosol mitigation policy tied with strong climate mitigation (Shared Socioeconomic Pathway 1-1.9) the Asian aerosol reductions can add around 8 years' worth of current-day global warming during the next few decades.

scholarly journals Local and remote mean and extreme temperature response to regional aerosol emissions reductions

2020 ◽  
Vol 20 (5) ◽  
pp. 3009-3027 ◽  
Author(s):  
Daniel M. Westervelt ◽  
Nora R. Mascioli ◽  
Arlene M. Fiore ◽  
Andrew J. Conley ◽  
Jean-François Lamarque ◽  
...  
Keyword(s):  
Extreme Temperature ◽  
Temperature Response ◽  
Carbonaceous Aerosol ◽  
The Arctic ◽  
Emissions Reductions ◽  
Aerosol Forcing ◽  
Regional Temperature ◽  
The Tropics ◽  
Aerosol Emissions ◽  
Temperature Responses

Abstract. The climatic implications of regional aerosol and precursor emissions reductions implemented to protect human health are poorly understood. We investigate the mean and extreme temperature response to regional changes in aerosol emissions using three coupled chemistry–climate models: NOAA GFDL CM3, NCAR CESM1, and NASA GISS-E2. Our approach contrasts a long present-day control simulation from each model (up to 400 years with perpetual year 2000 or 2005 emissions) with 14 individual aerosol emissions perturbation simulations (160–240 years each). We perturb emissions of sulfur dioxide (SO2) and/or carbonaceous aerosol within six world regions and assess the statistical significance of mean and extreme temperature responses relative to internal variability determined by the control simulation and across the models. In all models, the global mean surface temperature response (perturbation minus control) to SO2 and/or carbonaceous aerosol is mostly positive (warming) and statistically significant and ranges from +0.17 K (Europe SO2) to −0.06 K (US BC). The warming response to SO2 reductions is strongest in the US and Europe perturbation simulations, both globally and regionally, with Arctic warming up to 1 K due to a removal of European anthropogenic SO2 emissions alone; however, even emissions from regions remote to the Arctic, such as SO2 from India, significantly warm the Arctic by up to 0.5 K. Arctic warming is the most robust response across each model and several aerosol emissions perturbations. The temperature response in the Northern Hemisphere midlatitudes is most sensitive to emissions perturbations within that region. In the tropics, however, the temperature response to emissions perturbations is roughly the same in magnitude as emissions perturbations either within or outside of the tropics. We find that climate sensitivity to regional aerosol perturbations ranges from 0.5 to 1.0 K (W m−2)−1 depending on the region and aerosol composition and is larger than the climate sensitivity to a doubling of CO2 in two of three models. We update previous estimates of regional temperature potential (RTP), a metric for estimating the regional temperature responses to a regional emissions perturbation that can facilitate assessment of climate impacts with integrated assessment models without requiring computationally demanding coupled climate model simulations. These calculations indicate a robust regional response to aerosol forcing within the Northern Hemisphere midlatitudes, regardless of where the aerosol forcing is located longitudinally. We show that regional aerosol perturbations can significantly increase extreme temperatures on the regional scale. Except in the Arctic in the summer, extreme temperature responses largely mirror mean temperature responses to regional aerosol perturbations through a shift of the temperature distributions and are mostly dominated by local rather than remote aerosol forcing.

Decomposing local and remote surface temperature impacts of Asian aerosols

2021 ◽  
Author(s):  
Joonas Merikanto ◽  
Kalle Nordling ◽  
Petri Räisänen ◽  
Jouni Räisänen ◽  
Declan O'Donnell ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Energy Transport ◽  
East Asian ◽  
Temperature Response ◽  
Longwave Radiation ◽  
Shortwave Radiation ◽  
Anthropogenic Aerosols ◽  
Anthropogenic Aerosol ◽  
Clear Sky ◽  
Temperature Responses

<p>We investigate how a regionally confined radiative forcing of South and East Asian aerosols translate into local and remote surface temperature responses across the globe. To do so, we carry out equilibrium climate simulations with and without modern day South and East Asian anthropogenic aerosols in two climate models with independent development histories (ECHAM6.1 and NorESM1).  We run the models with the same anthropogenic aerosol representations via MACv2-SP (a simple plume implementation of the 2<sup>nd</sup> version of the Max Planck Institute Aerosol Climatology). This leads to a near identical change in instantaneous direct and indirect aerosol forcing due to removal of Asian aerosols in the two models. We then robustly decompose and compare the energetic pathways that give rise to the global and regional surface temperature effects in the models by a novel temperature response decomposition method, which translated the changes in atmospheric and surface energy fluxes into surface temperature responses by using a concept of planetary emissivity.  </p><p>We find that the removal of South and East Asian anthropogenic aerosols leads to strong local warming  response from increased clear-sky shortwave radiation over the region, combined with opposing warming and cooling responses due to changes in cloud longwave and shortwave radiation. However, the local warming response is strongly modulated by the changes in horizontal atmospheric energy transport. Atmospheric energy transport and changes in clear-sky longwave radiation redistribute the surface temperature responses efficiently across the Northern hemisphere, and to a lesser extent also over the Southern hemisphere. The model-mean global surface temperature response to Asian anthropogenic aerosol removal is 0.26±0.04 °C (0.22±0.03 for ECHAM6.1 and 0.30±0.03 °C for NorESM1) of warming. Model-to-model differences in global surface temperature response mainly arise from differences in longwave cloud (0.01±0.01 for ECHAM6.1 and 0.05±0.01 °C for NorESM1) and shortwave cloud (0.03±0.03 for ECHAM6.1 and 0.07±0.02 °C for NorESM1) responses. The differences in cloud responses between the models also dominate the differences in regional temperature responses. In both models, the Northern hemispheric surface warming amplifies towards the Arctic, where the total temperature response is highly seasonal and modulated by seasonal changes in oceanic heat exchange and clear-sky longwave radiation.</p><p>We estimate that under a strong Asian aerosol mitigation policy tied with strong greenhouse gas mitigation (Shared Socioeconomic Pathway 1-1.9) the Asian aerosol reductions can add around 8 years’ worth of current day global warming during the next few decades.</p>

Surface Arctic Amplification Factors in CMIP5 Models: Land and Oceanic Surfaces and Seasonality

2016 ◽  
Vol 29 (9) ◽  
pp. 3297-3316 ◽  
Author(s):  
Alexandre Laîné ◽  
Masakazu Yoshimori ◽  
Ayako Abe-Ouchi
Keyword(s):  
Global Warming ◽  
Arctic Ocean ◽  
Kernel Method ◽  
The Arctic ◽  
Cmip5 Models ◽  
Primary Role ◽  
Arctic Amplification ◽  
Surface Warming ◽  
The Arctic Ocean ◽  
The Tropics

Abstract Arctic amplification (AA) is a major characteristic of observed global warming, yet the different mechanisms responsible for it and their quantification are still under investigation. In this study, the roles of different factors contributing to local surface warming are quantified using the radiative kernel method applied at the surface after 100 years of global warming under a representative concentration pathway 4.5 (RCP4.5) scenario simulated by 32 climate models from phase 5 of the Coupled Model Intercomparison Project. The warming factors and their seasonality for land and oceanic surfaces were investigated separately and for different domains within each surface type where mechanisms differ. Common factors contribute to both land and oceanic surface warming: tropospheric-mean atmospheric warming and greenhouse gas increases (mostly through water vapor feedback) for both tropical and Arctic regions, nonbarotropic warming and surface warming sensitivity effects (negative in the tropics, positive in the Arctic), and warming cloud feedback in the Arctic in winter. Some mechanisms differ between land and oceanic surfaces: sensible and latent heat flux in the tropics, albedo feedback peaking at different times of the year in the Arctic due to different mean latitudes, a very large summer energy uptake and winter release by the Arctic Ocean, and a large evaporation enhancement in winter over the Arctic Ocean, whereas the peak occurs in summer over the ice-free Arctic land. The oceanic anomalous energy uptake and release is further studied, suggesting the primary role of seasonal variation of oceanic mixed layer temperature changes.

scholarly journals Arctic Climate Variability and Trends from Satellite Observations

2012 ◽  
Vol 2012 ◽  
pp. 1-22 ◽  
Author(s):  
Xuanji Wang ◽  
Jeffrey Key ◽  
Yinghui Liu ◽  
Charles Fowler ◽  
James Maslanik ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Surface Temperature ◽  
Cloud Fraction ◽  
Arctic Sea Ice ◽  
Satellite Observations ◽  
Arctic Climate ◽  
The Arctic ◽  
Climate Indices ◽  
Surface Warming

Arctic climate has been changing rapidly since the 1980s. This work shows distinctly different patterns of change in winter, spring, and summer for cloud fraction and surface temperature. Satellite observations over 1982–2004 have shown that the Arctic has warmed up and become cloudier in spring and summer, but cooled down and become less cloudy in winter. The annual mean surface temperature has increased at a rate of 0.34°C per decade. The decadal rates of cloud fraction trends are −3.4%, 2.3%, and 0.5% in winter, spring, and summer, respectively. Correspondingly, annually averaged surface albedo has decreased at a decadal rate of −3.2%. On the annual average, the trend of cloud forcing at the surface is −2.11 W/m2per decade, indicating a damping effect on the surface warming by clouds. The decreasing sea ice albedo and surface warming tend to modulate cloud radiative cooling effect in spring and summer. Arctic sea ice has also declined substantially with decadal rates of −8%, −5%, and −15% in sea ice extent, thickness, and volume, respectively. Significant correlations between surface temperature anomalies and climate indices, especially the Arctic Oscillation (AO) index, exist over some areas, implying linkages between global climate change and Arctic climate change.

scholarly journals Distinct roles of land cover in regulating spatial variabilities of temperature responses to radiative effects of aerosols and clouds

2021 ◽  
Author(s):  
Linyi Wei ◽  
Yong Wang ◽  
Shu Liu ◽  
Guang J. Zhang ◽  
Bin Wang
Keyword(s):  
Land Cover ◽  
Surface Temperature ◽  
Land Surface ◽  
Western Europe ◽  
Temperature Response ◽  
The United States ◽  
Surface Energy Budget ◽  
Radiative Effects ◽  
Anthropogenic Aerosol ◽  
Temperature Responses

Abstract Surface temperature responses to aerosol and cloud radiative perturbations are complicated by the underlying land surface processes. To disentangle this complexity, this study investigates the role of land surfaces in the radiative effects of aerosols and clouds on surface temperature from a terrestrial surface energy budget perspective using the National Center for Atmospheric Research (NCAR) Community Earth System Model version 1.2.1 (CESM1.2.1). It is found that land cover enhances the spatial variation of the temperature response to aerosol direct radiative effects (DRE) and cloud radiative effects (CRE) during daytime and nighttime respectively while it reduces that of the temperature response to CRE during the daytime by collocation of local surface climate sensitivity and aerosol DRE and CRE. With identical anthropogenic aerosol emissions over eight major emission regions in the past, present and future projections including Brazil, China, East Africa, India, Indonesia, South Africa, the United States and Western Europe, local temperature responses to aerosol DRE (CRE) are more strongly regulated by land cover in the daytime (nighttime).

scholarly journals Understanding the surface temperature response and its uncertainty to CO<sub>2</sub>, CH<sub>4</sub>, black carbon, and sulfate

2021 ◽  
Vol 21 (19) ◽  
pp. 14941-14958
Author(s):  
Kalle Nordling ◽  
Hannele Korhonen ◽  
Jouni Räisänen ◽  
Antti-Ilari Partanen ◽  
Bjørn H. Samset ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Black Carbon ◽  
Surface Albedo ◽  
Climate Models ◽  
Temperature Response ◽  
Regional Model ◽  
Climate Forcing ◽  
Clear Sky ◽  
Temperature Responses ◽  
Global Surface

Abstract. Understanding the regional surface temperature responses to different anthropogenic climate forcing agents, such as greenhouse gases and aerosols, is crucial for understanding past and future regional climate changes. In modern climate models, the regional temperature responses vary greatly for all major forcing agents, but the causes of this variability are poorly understood. Here, we analyze how changes in atmospheric and oceanic energy fluxes due to perturbations in different anthropogenic climate forcing agents lead to changes in global and regional surface temperatures. We use climate model data on idealized perturbations in four major anthropogenic climate forcing agents (CO2, CH4, sulfate, and black carbon aerosols) from Precipitation Driver Response Model Intercomparison Project (PDRMIP) climate experiments for six climate models (CanESM2, HadGEM2-ES, NCAR-CESM1-CAM4, NorESM1, MIROC-SPRINTARS, GISS-E2). Particularly, we decompose the regional energy budget contributions to the surface temperature responses due to changes in longwave and shortwave fluxes under clear-sky and cloudy conditions, surface albedo changes, and oceanic and atmospheric energy transport. We also analyze the regional model-to-model temperature response spread due to each of these components. The global surface temperature response stems from changes in longwave emissivity for greenhouse gases (CO2 and CH4) and mainly from changes in shortwave clear-sky fluxes for aerosols (sulfate and black carbon). The global surface temperature response normalized by effective radiative forcing is nearly the same for all forcing agents (0.63, 0.54, 0.57, 0.61 K W−1 m2). While the main physical processes driving global temperature responses vary between forcing agents, for all forcing agents the model-to-model spread in temperature responses is dominated by differences in modeled changes in longwave clear-sky emissivity. Furthermore, in polar regions for all forcing agents the differences in surface albedo change is a key contributor to temperature responses and its spread. For black carbon, the modeled differences in temperature response due to shortwave clear-sky radiation are also important in the Arctic. Regional model-to-model differences due to changes in shortwave and longwave cloud radiative effect strongly modulate each other. For aerosols, clouds play a major role in the model spread of regional surface temperature responses. In regions with strong aerosol forcing, the model-to-model differences arise from shortwave clear-sky responses and are strongly modulated by combined temperature responses to oceanic and atmospheric heat transport in the models.

A Study on the Change of Arctic Ocean Surface Temperature in CESM

2020 ◽  
Author(s):  
Peiyan Xie ◽  
Hailun He ◽  
Shuang Li
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Global Climate ◽  
The Arctic ◽  
Lower Latitude ◽  
Surface Warming ◽  
Arctic Sea ◽  
Community Earth System Model ◽  
The Arctic Oscillation ◽  
Arctic Area

&lt;p&gt;Since the 1950s, human has begun to explore the Arctic&amp;#160;area. As the scientific research goes further, scientists gradually realize the important role the Arctic plays in the global climate system, and it has been said the Arctic has an&amp;#160;amplifying&amp;#160;effect&amp;#160;on surface warming, which increases&amp;#160;2 to 3 times faster than the global average&amp;#160;increment. Given the importance of this area, we try to figure out the relationship among the Arctic sea surface temperature&amp;#160;(SST), sea ice index and the Arctic Oscillation (AO) in this paper. By using Community Earth System Model (CESM), we calculated an ocean-seaice-atmosphere coupled 200-year experiment. As a result, we found out that the variation&amp;#160;of Arctic SST is negatively correlated with the change of sea ice area.&amp;#160;There is a significant correlation between the change of SST&amp;#160;and AO, which can lead to the anomaly of&amp;#160;air&amp;#160;heat transport between the Arctic area and the areas in lower latitude.&lt;/p&gt;

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