scholarly journals Local and remote temperature response of regional SO<sub>2</sub> emissions

2018 ◽  
Author(s):  
Anna Lewinschal ◽  
Annica M. L. Ekman ◽  
Hans-Christen Hansson ◽  
Maria Sand ◽  
Terje K. Berntsen ◽  
...  
Keyword(s):  
East Asia ◽  
South Asia ◽  
Temperature Change ◽  
Radiative Forcing ◽  
Regional Scale ◽  
Temperature Response ◽  
The Arctic ◽  
Emission Region ◽  
So2 Emissions ◽  
Emission Changes

Abstract. Short-lived anthropogenic climate forcers, such as sulphate aerosols, affect both climate and air quality. Despite being short-lived, these forcers do not affect temperatures only locally; regions far away from the emission sources are also affected. Climate metrics are often used e.g. in a policy context to compare the climate impact of different anthropogenic forcing agents. These metrics typically relate a forcing change in a certain region with a temperature change in another region and thus often require a separate model to convert emission changes to radiative forcing changes. In this study, we used a coupled Earth System Model (NorESM) to calculate emission-to-temperature-response metrics for sulphur dioxide (SO2) emission changes in four different policy-relevant regions: Europe, North America, East Asia and South Asia. We first increased the SO2 emissions in each individual region by an amount giving approximately the same global average radiative forcing change (−0.45 W m−2). The global mean temperature change per unit sulphur emission compared to the control experiment was independent of emission region and equal to ∼ 0.006 K/TgSyr−1. On a regional scale, the Arctic showed the largest temperature response in all experiments. The second largest temperature change occurred in the region of the imposed emission increase, except when South Asian emissions were changed; in this experiment, the temperature response was approximately the same in South Asia and East Asia. We also examined the non-linearity of the temperature response by removing all anthropogenic SO2 emissions over Europe in one experiment. In this case, the temperature response (both global and regional) was twice of that in the corresponding experiment with a European emission increase. This nonlinearity in the temperature response is one of many uncertainties associated with the use of simplified climate metrics.

scholarly journals Local and remote temperature response of regional SO<sub>2</sub> emissions

2019 ◽  
Vol 19 (4) ◽  
pp. 2385-2403 ◽  
Author(s):  
Anna Lewinschal ◽  
Annica M. L. Ekman ◽  
Hans-Christen Hansson ◽  
Maria Sand ◽  
Terje K. Berntsen ◽  
...  
Keyword(s):  
East Asia ◽  
South Asia ◽  
Temperature Change ◽  
Radiative Forcing ◽  
Temperature Response ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
So2 Emissions ◽  
Emission Changes

Abstract. Short-lived anthropogenic climate forcers (SLCFs), such as sulfate aerosols, affect both climate and air quality. Despite being short-lived, these forcers do not affect temperatures only locally; regions far away from the emission sources are also affected. Climate metrics are often used in a policy context to compare the climate impact of different anthropogenic forcing agents. These metrics typically relate a forcing change in a certain region with a temperature change in another region and thus often require a separate model to convert emission changes to radiative forcing (RF) changes. In this study, we used a coupled Earth system model, NorESM (Norwegian Earth System Model), to calculate emission-to-temperature-response metrics for sulfur dioxide (SO2) emission changes in four different policy-relevant regions: Europe (EU), North America (NA), East Asia (EA) and South Asia (SA). We first increased the SO2 emissions in each individual region by an amount giving approximately the same global average radiative forcing change (−0.45 Wm−2). The global mean temperature change per unit sulfur emission compared to the control experiment was independent of emission region and equal to ∼0.006 K(TgSyr−1)−1. On a regional scale, the Arctic showed the largest temperature response in all experiments. The second largest temperature change occurred in the region of the imposed emission increase, except when South Asian emissions were changed; in this experiment, the temperature response was approximately the same in South Asia and East Asia. We also examined the non-linearity of the temperature response by removing all anthropogenic SO2 emissions over Europe in one experiment. In this case, the temperature response (both global and regional) was twice that in the corresponding experiment with a European emission increase. This non-linearity in the temperature response is one of many uncertainties associated with the use of simplified climate metrics.

scholarly journals Regional temperature change potentials for short-lived climate forcers based on radiative forcing from multiple models

2017 ◽  
Vol 17 (17) ◽  
pp. 10795-10809 ◽  
Author(s):  
Borgar Aamaas ◽  
Terje K. Berntsen ◽  
Jan S. Fuglestvedt ◽  
Keith P. Shine ◽  
William J. Collins
Keyword(s):  
East Asia ◽  
Temperature Change ◽  
Northern Hemisphere ◽  
Radiative Forcing ◽  
Atmospheric Transport ◽  
Winter Season ◽  
Temperature Response ◽  
The Arctic ◽  
Regional Temperature ◽  
Hemisphere Winter

Abstract. We calculate the absolute regional temperature change potential (ARTP) of various short-lived climate forcers (SLCFs) based on detailed radiative forcing (RF) calculations from four different models. The temperature response has been estimated for four latitude bands (90–28° S, 28° S–28° N, 28–60° N, and 60–90° N). The regional pattern in climate response not only depends on the relationship between RF and surface temperature, but also on where and when emissions occurred and atmospheric transport, chemistry, interaction with clouds, and deposition. We present four emissions cases covering Europe, East Asia, the global shipping sector, and the entire globe. Our study is the first to estimate ARTP values for emissions during Northern Hemisphere summer (May–October) and winter season (November–April). The species studied are aerosols and aerosol precursors (black carbon, organic carbon, SO2, NH3), ozone precursors (NOx, CO, volatile organic compound), and methane (CH4). For the response to BC in the Arctic, we take into account the vertical structure of the RF in the atmosphere, and an enhanced climate efficacy for BC deposition on snow. Of all SLCFs, BC is the most sensitive to where and when the emissions occur, as well as giving the largest difference in response between the latitude bands. The temperature response in the Arctic per unit BC emission is almost four times larger and more than two times larger than the global average for Northern Hemisphere winter emissions for Europe and East Asia, respectively. The latitudinal breakdown likely gives a better estimate of the global temperature response as it accounts for varying efficacies with latitude. An annual pulse of non-methane SLCF emissions globally (representative of 2008) lead to a global cooling. In contrast, winter emissions in Europe and East Asia give a net warming in the Arctic due to significant warming from BC deposition on snow.

scholarly journals Global and regional temperature-change potentials for near-term climate forcers

2012 ◽  
Vol 12 (9) ◽  
pp. 23261-23290 ◽  
Author(s):  
W. J. Collins ◽  
M. M. Fry ◽  
H. Yu ◽  
J. S. Fuglestvedt ◽  
D. T. Shindell ◽  
...  
Keyword(s):  
Temperature Change ◽  
Radiative Forcing ◽  
Transport Model ◽  
Task Force ◽  
Temperature Response ◽  
The Arctic ◽  
Emission Region ◽  
Nitric Oxides ◽  
Chemical Transport Model ◽  
Near Term

Abstract. We examine the climate effects of the emissions of near-term climate forcers (NTCFs) from 4 continental regions (East Asia, Europe, North America and South Asia) using radiative forcing from the task force on hemispheric transport of air pollution source-receptor global chemical transport model simulations. These simulations model the transport of 3 aerosol species (sulphate, particulate organic matter and black carbon) and 4 ozone precursors (methane, nitric oxides (NOx), volatile organic compounds and carbon monoxide). From the equilibrium radiative forcing results we calculate global climate metrics, global warming potentials (GWPs) and global temperature change potentials (GTPs) and show how these depend on emission region, and can vary as functions of time. For the aerosol species, the GWP(100) values are −37±12, −46±20, and 350±200 for SO2, POM and BC respectively for the direct effects only. The corresponding GTP(100) values are −5.2±2.4, −6.5±3.5, and 50±33. This analysis is further extended by examining the temperature-change impacts in 4 latitude bands. This shows that the latitudinal pattern of the temperature response to emissions of the NTCFs does not directly follow the pattern of the diagnosed radiative forcing. For instance temperatures in the Arctic latitudes are particularly sensitive to NTCF emissions in the northern mid-latitudes. At the 100-yr time horizon the ARTPs show NOx emissions can have a warming effect in the northern mid and high latitudes, but cooling in the tropics and Southern Hemisphere. The northern mid-latitude temperature response to northern mid-latitude emissions of most NTCFs is approximately twice as large as would be implied by the global average.

scholarly journals Regional temperature change potentials for short lived climate forcers from multiple models

2017 ◽  
Author(s):  
Borgar Aamaas ◽  
Terje K. Berntsen ◽  
Jan S. Fuglestvedt ◽  
Keith P. Shine ◽  
William J. Collins
Keyword(s):  
East Asia ◽  
Temperature Change ◽  
Northern Hemisphere ◽  
Radiative Forcing ◽  
Atmospheric Transport ◽  
Winter Season ◽  
Temperature Response ◽  
The Arctic ◽  
Regional Temperature ◽  
Hemisphere Winter

Abstract. We calculate the absolute regional temperature change potential (ARTP) of various short lived climate forcers (SLCFs) based on detailed radiative forcing (RF) calculations from four different models. The temperature response has been estimated for four latitude bands (90–28° S, 28° S–28° N, 28–60° N, and 60–90° N). The regional pattern in climate response not only depends on the relationship between RF and surface temperature, but also on where and when emissions occurred and atmospheric transport, chemistry, interaction with clouds, and deposition. We present four emissions cases covering Europe, East Asia, the global shipping sector, and the globe. Our study is the first to estimate ARTP values for emissions during Northern Hemisphere summer (May–October) and winter season (November–April). The species studied are aerosols and aerosol precursors (black carbon (BC), organic carbon (OC), SO2, NH3), ozone precursors (NOx, CO, volatile organic compound (VOC)), and methane (CH4). For the response to BC in the Arctic, we take into account the vertical structure of the RF in the atmosphere, and an enhanced climate efficacy for BC deposition on snow. Of all SLCFs, BC is the most sensitive to where and when the emissions occur, as well as giving the largest difference in response between the latitude bands. The temperature response in the Arctic is almost 4 times larger and more than 2 times larger than the global average for Northern Hemisphere winter emissions for Europe and East Asia, respectively. The latitudinal breakdown gives likely a better estimate of the global temperature response as it accounts for varying efficacies with latitude. An annual pulse of non-methane SLCFs emissions globally (representative of 2008) leads to a global cooling. Whereas, winter emissions in Europe and East Asia give a net warming in the Arctic due to significant warming from BC deposition on snow.

scholarly journals Global and regional temperature-change potentials for near-term climate forcers

2013 ◽  
Vol 13 (5) ◽  
pp. 2471-2485 ◽  
Author(s):  
W. J. Collins ◽  
M. M. Fry ◽  
H. Yu ◽  
J. S. Fuglestvedt ◽  
D. T. Shindell ◽  
...  
Keyword(s):  
South Asia ◽  
Temperature Change ◽  
Temperature Response ◽  
The Arctic ◽  
Emission Region ◽  
Global Average ◽  
Ozone Precursors ◽  
Aerosol Emission ◽  
Regional Temperature ◽  
Near Term

Abstract. We examine the climate effects of the emissions of near-term climate forcers (NTCFs) from 4 continental regions (East Asia, Europe, North America and South Asia) using results from the Task Force on Hemispheric Transport of Air Pollution Source-Receptor global chemical transport model simulations. We address 3 aerosol species (sulphate, particulate organic matter and black carbon) and 4 ozone precursors (methane, reactive nitrogen oxides (NOx), volatile organic compounds and carbon monoxide). We calculate the global climate metrics: global warming potentials (GWPs) and global temperature change potentials (GTPs). For the aerosols these metrics are simply time-dependent scalings of the equilibrium radiative forcings. The GTPs decrease more rapidly with time than the GWPs. The aerosol forcings and hence climate metrics have only a modest dependence on emission region. The metrics for ozone precursors include the effects on the methane lifetime. The impacts via methane are particularly important for the 20 yr GTPs. Emissions of NOx and VOCs from South Asia have GWPs and GTPs of higher magnitude than from the other Northern Hemisphere regions. The analysis is further extended by examining the temperature-change impacts in 4 latitude bands, and calculating absolute regional temperature-change potentials (ARTPs). The latitudinal pattern of the temperature response does not directly follow the pattern of the diagnosed radiative forcing. We find that temperatures in the Arctic latitudes appear to be particularly sensitive to BC emissions from South Asia. The northern mid-latitude temperature response to northern mid-latitude emissions is approximately twice as large as the global average response for aerosol emission, and about 20–30% larger than the global average for methane, VOC and CO emissions.

scholarly journals Surface temperature response to regional Black Carbon emissions: Do location and magnitude matter?

2019 ◽  
Author(s):  
Maria Sand ◽  
Terje K. Berntsen ◽  
Annica Ekman ◽  
Hans-Christen Hansson ◽  
Anna Lewinschal
Keyword(s):  
North America ◽  
Surface Temperature ◽  
South Asia ◽  
Black Carbon ◽  
Temperature Change ◽  
Radiative Forcing ◽  
Sea Surface ◽  
Emission Region ◽  
Regional Temperature ◽  
Fully Coupled

Abstract. Aerosol radiative forcing can influence climate both locally and far outside the emission region. Here we investigate Black Carbon (BC) aerosols emitted in four major emissions areas and evaluate the importance of emission location and magnitude, as well as the concept of the absolute regional temperature-change potentials. We perform simulations with a climate model (NorESM) with a fully coupled ocean and with fixed sea surface temperatures. BC emissions are increased by a rate of 10 and 20 in South Asia, North America and Europe, respectively, and by 5 and 10 in East Asia (due to higher emissions there). We find strikingly similar regional surface temperature responses and geographical patterns per unit BC emission in Europe and North America, but somewhat lower temperature sensitivities for East Asian emissions. BC emitted in South Asia shows a different geographical pattern by changing the Indian monsoon and cooling the surface. Choosing the highest emission rate results in lower surface temperature change per emission unit compared to the lowest rate, but the difference is generally not statistically significant except for the Arctic. An advantage of high-perturbation simulations is the clearer emergence of regional signals. Our results show that the linearity of normalized temperature effects of BC is fairly well preserved despite the relatively large perturbations, but that regional temperature coefficients calculated from high perturbations may be a conservative estimate. Regardless of emission region, BC causes a northward shift of the ITCZ, and this shift is apparent both with fully coupled ocean and with fixed sea surface temperatures. For these regional BC emissions perturbations, we find that the effective radiative forcing is not a good measure of the climate response.

scholarly journals Global and regional radiative forcing from 20 % reductions in BC, OC and SO<sub>4</sub> – an HTAP2 multi-model study

2016 ◽  
Vol 16 (21) ◽  
pp. 13579-13599 ◽  
Author(s):  
Camilla Weum Stjern ◽  
Bjørn Hallvard Samset ◽  
Gunnar Myhre ◽  
Huisheng Bian ◽  
Mian Chin ◽  
...  
Keyword(s):  
East Asia ◽  
Radiative Forcing ◽  
General Circulation ◽  
Temperature Response ◽  
Anthropogenic Aerosols ◽  
Aerosol Forcing ◽  
Source Regions ◽  
Intercontinental Transport ◽  
Emission Changes ◽  
The Impact

Abstract. In the Hemispheric Transport of Air Pollution Phase 2 (HTAP2) exercise, a range of global atmospheric general circulation and chemical transport models performed coordinated perturbation experiments with 20 % reductions in emissions of anthropogenic aerosols, or aerosol precursors, in a number of source regions. Here, we compare the resulting changes in the atmospheric load and vertically resolved profiles of black carbon (BC), organic aerosols (OA) and sulfate (SO4) from 10 models that include treatment of aerosols. We use a set of temporally, horizontally and vertically resolved profiles of aerosol forcing efficiency (AFE) to estimate the impact of emission changes in six major source regions on global radiative forcing (RF) pertaining to the direct aerosol effect, finding values between. 51.9 and 210.8 mW m−2 Tg−1 for BC, between −2.4 and −17.9 mW m−2 Tg−1 for OA and between −3.6 and −10.3 W m−2 Tg−1 for SO4. In most cases, the local influence dominates, but results show that mitigations in south and east Asia have substantial impacts on the radiative budget in all investigated receptor regions, especially for BC. In Russia and the Middle East, more than 80 % of the forcing for BC and OA is due to extra-regional emission reductions. Similarly, for North America, BC emissions control in east Asia is found to be more important than domestic mitigations, which is consistent with previous findings. Comparing fully resolved RF calculations to RF estimates based on vertically averaged AFE profiles allows us to quantify the importance of vertical resolution to RF estimates. We find that locally in the source regions, a 20 % emission reduction strengthens the radiative forcing associated with SO4 by 25 % when including the vertical dimension, as the AFE for SO4 is strongest near the surface. Conversely, the local RF from BC weakens by 37 % since BC AFE is low close to the ground. The fraction of BC direct effect forcing attributable to intercontinental transport, on the other hand, is enhanced by one-third when accounting for the vertical aspect, because long-range transport primarily leads to aerosol changes at high altitudes, where the BC AFE is strong. While the surface temperature response may vary with the altitude of aerosol change, the analysis in the present study is not extended to estimates of temperature or precipitation changes.

scholarly journals Surface temperature response to regional black carbon emissions: do location and magnitude matter?

2020 ◽  
Vol 20 (5) ◽  
pp. 3079-3089 ◽  
Author(s):  
Maria Sand ◽  
Terje K. Berntsen ◽  
Annica M. L. Ekman ◽  
Hans-Christen Hansson ◽  
Anna Lewinschal
Keyword(s):  
North America ◽  
Surface Temperature ◽  
South Asia ◽  
Radiative Forcing ◽  
Temperature Response ◽  
Sea Surface ◽  
Emission Region ◽  
Surface Temperatures ◽  
Regional Temperature ◽  
Fully Coupled

Abstract. Aerosol radiative forcing can influence climate both locally and far outside the emission region. Here we investigate black carbon (BC) aerosols emitted in four major emission areas and evaluate the importance of emission location and magnitude as well as the concept of the absolute regional temperature-change potentials (ARTP). We perform simulations with a climate model (NorESM) with a fully coupled ocean and with fixed sea surface temperatures. BC emissions for year 2000 are increased by factors of 10 and 20 in South Asia, North America, and Europe, respectively, and by 5 and 10 in East Asia (due to higher emissions there). The perturbed simulations and a reference simulation are run for 100 years with three ensemble members each. We find strikingly similar regional surface temperature responses and geographical patterns per unit BC emission in Europe and North America but somewhat lower temperature sensitivities for East Asian emissions. BC emitted in South Asia shows a different geographical pattern in surface temperatures, by changing the Indian monsoon and cooling the surface. We find that the ARTP approach rather accurately reproduces the fully coupled temperature response of NorESM. Choosing the highest emission rate results in lower surface temperature change per emission unit compared to the lowest rate, but the difference is generally not statistically significant except for the Arctic. An advantage of high-perturbation simulations is the clearer emergence of regional signals. Our results show that the linearity of normalized temperature effects of BC is fairly well preserved despite the relatively large perturbations but that regional temperature coefficients calculated from high perturbations may be a conservative estimate. Regardless of emission region, BC causes a northward shift of the ITCZ, and this shift is apparent both with a fully coupled ocean and with fixed sea surface temperatures. For these regional BC emission perturbations, we find that the effective radiative forcing is not a good measure of the climate response. A limitation of this study is the uncertainties in BC–cloud interactions and the amount of BC absorption, both of which are model dependent.

scholarly journals Role of radiatively forced temperature changes in enhanced semi-arid warming in the cold season over east Asia

2015 ◽  
Vol 15 (23) ◽  
pp. 13777-13786 ◽  
Author(s):  
X. Guan ◽  
J. Huang ◽  
R. Guo ◽  
H. Yu ◽  
P. Lin ◽  
...  
Keyword(s):  
East Asia ◽  
Human Activities ◽  
Radiative Forcing ◽  
Decadal Variability ◽  
Regional Scale ◽  
Warming Trend ◽  
Cold Season ◽  
Daily Maximum ◽  
Surface Temperature Change ◽  
Semi Arid

Abstract. As climate change has occurred over east Asia since the 1950s, intense interest and debate have arisen concerning the contribution of human activities to the observed warming in past decades. In this study, we investigate regional surface temperature change during the boreal cold season using a recently developed methodology that can successfully identify and separate the dynamically induced temperature (DIT) and radiatively forced temperature (RFT) changes in raw surface air temperature (SAT) data. For regional averages, DIT and RFT contribute 44 and 56 % to the SAT over east Asia, respectively. The DIT changes dominate the SAT decadal variability and are mainly determined by internal climate variability, represented by the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Atlantic Multi-decadal Oscillation (AMO). Radiatively forced SAT changes have made a major contribution to the global-scale warming trend and the regional-scale enhanced semi-arid warming (ESAW). Such enhanced warming is also found in radiatively forced daily maximum and minimum SAT. The long-term global-mean SAT warming trend is mainly related to radiative forcing produced by global well-mixed greenhouse gases. The regional anthropogenic radiative forcing, however, caused the enhanced warming in the semi-arid region, which may be closely associated with local human activities. Finally, the relationship between the so-called "global warming hiatus" and regional enhanced warming is discussed.

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