Arctic Amplification Response to Individual Climate Drivers

Stjern, Camilla W.; Lund, Marianne T.; Samset, B. H.; Myhre, Gunnar; Forster, Piers M.; Andrews, Timothy; Boucher, Oliviér; Faluvegi, Gregory; Fläschner, Dagmar; Iversen, Trond; Kasoar, Matthew; Kharin, Viatcheslav; Kirkevåg, Alf; Lamarque, J. F.; Olivié, Dirk; Richardson, T.; Sand, Maria; Shawki, Dilshad; Shindell, D. T.; Smith, Christopher J.; Takemura, Toshihiko; Voulgarakis, Apostolos

doi:10.1029/2018jd029726

Cited by 46 publications

(37 citation statements)

References 106 publications

(147 reference statements)

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“…5) resulting from a lack of a cloud lifetime effect in that model (Westervelt et al, 2017(Westervelt et al, , 2018. In all three models, the largest remote temperature responses are over the Arctic, owing to the well-established polar amplification phenomenon (Smith et al, 2019;Stjern et al, 2019). Surface temperature response is strongest in the US SO 2 and Europe SO 2 simulations in all three models, with annual mean local and remote temperature increases of up to 1 K or higher.…”

Section: Extreme Indicesmentioning

confidence: 87%

“…Emissions of aerosols and their precursors are spatially heterogeneous and short-lived and thereby expected to exert complex responses as emissions of air pollutants are reduced through policies enacted to protect human health. Emissions of sulfur dioxide (SO 2 ), black carbon (BC), and organic carbon aerosol (OA) have decreased throughout the United States and Europe for several decades (Leibensperger et al, 2012;Tørseth et al, 2012). On the other hand, emissions have largely increased in recent decades in countries such as China, India, and others in the Global South; however, since 2013, emissions of SO 2 have begun to decline at least in China, while emissions in India continue to increase (Fontes et al, 2017;Li et al, 2017;Lu et al, 2011;Samset et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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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.

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Section: Extreme Indicesmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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“…Removal of US anthropogenic SO 2 emissions showed robust patterns of temperature responses over land, with increases in temperature for most of the Northern Hemisphere land regions and the strongest response towards the Arctic (Conley et al, 2018;Shindell et al, 2015). Other recent model studies indicate an amplification of the temperature response towards the Arctic due to local and remote aerosol forcing Westervelt et al, 2018;Stjern et al, 2019). Furthermore, model perturbation simulations with increasing SO 2 in Europe, North America, East Asia and South Asia showed a consistent cooling almost everywhere over the Northern Hemisphere with the Arctic revealing the largest temperature response in all experiments (Lewinschal et al, 2019).…”

Section: Introductionmentioning

confidence: 84%

Fast responses on pre-industrial climate from present-day aerosols in a CMIP6 multi-model study

et al. 2020

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Abstract. In this work, we use Coupled Model Intercomparison Project Phase 6 (CMIP6) simulations from 10 Earth system models (ESMs) and general circulation models (GCMs) to study the fast climate responses on pre-industrial climate, due to present-day aerosols. All models carried out two sets of simulations: a control experiment with all forcings set to the year 1850 and a perturbation experiment with all forcings identical to the control, except for aerosols with precursor emissions set to the year 2014. In response to the pattern of all aerosols effective radiative forcing (ERF), the fast temperature responses are characterized by cooling over the continental areas, especially in the Northern Hemisphere, with the largest cooling over East Asia and India, sulfate being the dominant aerosol surface temperature driver for present-day emissions. In the Arctic there is a warming signal for winter in the ensemble mean of fast temperature responses, but the model-to-model variability is large, and it is presumably linked to aerosol-induced circulation changes. The largest fast precipitation responses are seen in the tropical belt regions, generally characterized by a reduction over continental regions and presumably a southward shift of the tropical rain belt. This is a characteristic and robust feature among most models in this study, associated with weakening of the monsoon systems around the globe (Asia, Africa and America) in response to hemispherically asymmetric cooling from a Northern Hemisphere aerosol perturbation, forcing possibly the Intertropical Convergence Zone (ITCZ) and tropical precipitation to shift away from the cooled hemisphere despite that aerosols' effects on temperature and precipitation are only partly realized in these simulations as the sea surface temperatures are kept fixed. An interesting feature in aerosol-induced circulation changes is a characteristic dipole pattern with intensification of the Icelandic Low and an anticyclonic anomaly over southeastern Europe, inducing warm air advection towards the northern polar latitudes in winter.

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“…Arctic surface air temperature has risen at twice the rate of the global mean over the past three decades. This phenomenon is called Arctic amplification (Serreze and Barry, 2011), and our understanding of its causes is inadequate (Pithan and Mauritsen, 2014;Stjern et al, 2019). Important consequences of the rapidly increasing temperature in the Arctic are the loss of ice, resulting in the reduction of ice extent; loss of thickness; and a reduced fraction of multiyear ice (Stroeve et al, 2012) and the increasing rate of loss of the Greenland ice cap (Mouginot et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Long-term time series of Arctic tropospheric BrO derived from UV–VIS satellite remote sensing and its relation to first-year sea ice

et al. 2020

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Abstract. Every polar spring, phenomena called bromine explosions occur over sea ice. These bromine explosions comprise photochemical heterogeneous chain reactions that release bromine molecules, Br2, to the troposphere and lead to tropospheric plumes of bromine monoxide, BrO. This autocatalytic mechanism depletes ozone, O3, in the boundary layer and troposphere and thereby changes the oxidizing capacity of the atmosphere. The phenomenon also leads to accelerated deposition of metals (e.g., Hg). In this study, we present a 22-year (1996 to 2017) consolidated and consistent tropospheric BrO dataset north of 70∘ N, derived from four different ultraviolet–visible (UV–VIS) satellite instruments (GOME, SCIAMACHY, GOME-2A and GOME-2B). The retrieval data products from the different sensors are compared during periods of overlap and show good agreement (correlations of 0.82–0.98 between the sensors). From our merged time series of tropospheric BrO vertical column densities (VCDs), we infer changes in the bromine explosions and thus an increase in the extent and magnitude of tropospheric BrO plumes during the period of Arctic warming. We determined an increasing trend of about 1.5 % of the tropospheric BrO VCDs per year during polar springs, while the size of the areas where enhanced tropospheric BrO VCDs can be found has increased about 896 km2 yr−1. We infer from comparisons and correlations with sea ice age data that the reported changes in the extent and magnitude of tropospheric BrO VCDs are moderately related to the increase in first-year ice extent in the Arctic north of 70∘ N, both temporally and spatially, with a correlation coefficient of 0.32. However, the BrO plumes and thus bromine explosions show significant variability, which also depends, apart from sea ice, on meteorological conditions.

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Arctic Amplification Response to Individual Climate Drivers

Cited by 46 publications

References 106 publications

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

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

Fast responses on pre-industrial climate from present-day aerosols in a CMIP6 multi-model study

Long-term time series of Arctic tropospheric BrO derived from UV–VIS satellite remote sensing and its relation to first-year sea ice

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