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.

scholarly journals Role of radiatively forced temperature changes in enhanced semi-arid warming over East Asia

2015 ◽  
Vol 15 (16) ◽  
pp. 22975-23004 ◽  
Author(s):  
X. Guan ◽  
J. Huang ◽  
R. Guo ◽  
P. Lin ◽  
Y. Zhang
Keyword(s):  
East Asia ◽  
Human Activities ◽  
Radiative Forcing ◽  
Decadal Variability ◽  
Regional Scale ◽  
Surface Air Temperature ◽  
Warming Trend ◽  
Daily Maximum ◽  
Surface Temperature Change ◽  
Semi Arid

Abstract. As the climate change occurred over East Asia since 1950s, intense interest and debate have arisen concerning the contribution of human activities to the warming observed in previous decades. In this study, we investigate surface temperature change 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 make 43.7 and 56.3 % contributions to the SAT over East Asia, respectively. The DIT changes dominate the SAT decadal variability and are mainly determined by internal climate variability, such as the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Atlantic Multi-decadal Oscillation (AMO). The radiatively forced SAT changes made 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 global warming hiatus and regional enhanced warming is discussed.

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 Enhanced cold-season warming in semi-arid regions

2012 ◽  
Vol 12 (12) ◽  
pp. 5391-5398 ◽  
Author(s):  
J. Huang ◽  
X. Guan ◽  
F. Ji
Keyword(s):  
North America ◽  
Land Surface ◽  
Temperature Increase ◽  
Arid Regions ◽  
Surface Air Temperature ◽  
Warming Trend ◽  
Cold Season ◽  
Arid Areas ◽  
Temperature Trends ◽  
Semi Arid

Abstract. This study examined surface air temperature trends over global land from 1901–2009. It is found that the warming trend was particularly enhanced, in the boreal cold season (November to March) over semi-arid regions (with precipitation of 200–600 mm yr−1) showing a temperature increase of 1.53 °C as compared to the global annual mean temperature increase of 1.13 °C over land. In mid-latitude semi-arid areas of Europe, Asia, and North America, temperatures in the cold season increased by 1.41, 2.42, and 1.5 °C, respectively. The semi-arid regions contribute 44.46% to global annual-mean land-surface temperature trend. The mid-latitude semi-arid regions in the Northern Hemisphere contribute by 27.0% of the total, with the mid-latitude semi-arid areas in Europe, Asia, and North America accounting for 6.29%, 13.81%, and 6.85%, respectively. Such enhanced semi-arid warming (ESAW) imply drier and warmer trend of these regions.

scholarly journals Source attribution of Arctic aerosols and associated Arctic warming trend during 1980–2018

2020 ◽  
Author(s):  
Lili Ren ◽  
Yang Yang ◽  
Hailong Wang ◽  
Rudong Zhang ◽  
Pinya Wang ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Climate Model ◽  
Warming Trend ◽  
The Arctic ◽  
Source Attribution ◽  
Surface Temperature Change ◽  
Arctic Warming ◽  
Surface Warming ◽  
Poleward Heat Transport ◽  
Arctic Surface

Abstract. Observations show that the concentrations of Arctic sulfate and black carbon (BC) aerosols have declined since the early 1980s, which potentially contributed to the recent rapid Arctic warming. In this study, a global aerosol-climate model equipped with an Explicit Aerosol Source Tagging (CAM5-EAST) is applied to quantify the source apportionment of aerosols in the Arctic from sixteen source regions and the role of aerosol variations in the Arctic surface temperature change over the past four decades (1980–2018). The CAM5-EAST simulated surface concentrations of sulfate and BC in the Arctic had a decrease of 43 % and 23 %, respectively, in 2014–2018 relative to 1980–1984, mainly due to the reduction of emissions from Europe, Russia and Arctic local sources. Increases in emissions from South and East Asia led to positive trends of Arctic sulfate and BC in the upper troposphere. Changes in radiative forcing of sulfate and BC through aerosol-radiation interactions are found to exert a +0.145 K Arctic surface warming during 2014–2018 with respect to 1980–1984, with the largest contribution (61 %) by sulfate decrease, especially originating from the mid-latitude regions. The changes in atmospheric BC outside the Arctic produced an Arctic warming of +0.062 K, partially offset by −0.005 K of cooling due to atmospheric BC within the Arctic and −0.041 K related to the weakened snow/ice albedo effect of BC. Through aerosol-cloud interactions, the sulfate reduction gave an Arctic warming of +0.193 K between the first and last five years of 1980–2018, the majority of which is due to the mid-latitude emission change. Our results suggest that changes in aerosols over the mid-latitudes of the Northern Hemisphere have a larger impact on Arctic temperature than other regions associated with enhanced poleward heat transport from the aerosol-induced stronger meridional temperature gradient. The combined aerosol effects of sulfate and BC together produce an Arctic surface warming of +0.297 K during 1980–2018, explaining approximately 20 % of the observed Arctic warming during the same time period.

scholarly journals Geoengineering: Impact of Marine Cloud Brightening Control on the Extreme Temperature Change over East Asia

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1345
Author(s):  
Do-Hyun Kim ◽  
Ho-Jeong Shin ◽  
Il-Ung Chung
Keyword(s):  
East Asia ◽  
Radiative Forcing ◽  
Climate Models ◽  
Extreme Temperature ◽  
Global Climate Models ◽  
Maximum Temperature ◽  
Daily Minimum Temperature ◽  
Daily Maximum Temperature ◽  
Daily Maximum ◽  
Extreme Temperatures

We investigated the effect of artificial marine cloud brightening on extreme temperatures over East Asia. We used simulation data from five global climate models which have conducted the GeoMIP G4cdnc experiment. G4cdnc was designed to simulate an increase in the cloud droplet number concentration of the global marine lower clouds by 50% under the greenhouse gas forcing of the RCP4.5 scenario. G4cdnc decreased the net radiative forcing in the top of the atmosphere more over the ocean, alleviating the rise in mean temperature under RCP4.5 forcing. For extreme temperatures, G4cdnc reduced both the monthly minimum of daily minimum temperature (TNn) and monthly maximum of daily maximum temperature (TXx). The response of TNn was higher than that of TXx, especially in the winter, over the Sea of Okhotsk and the interior of the continent. This spatial heterogeneity and seasonality of the response were associated with sea ice–albedo and snow–albedo feedbacks. We also calculated the efficacy of warming mitigation as a measure of the relative effect of geoengineering. The efficacy for TXx was higher than that for TNn, opposite to the absolute effect. After the termination of geoengineering, both TNn and TXx tended to rapidly revert to their trend under the RCP4.5 forcing.

scholarly journals Enhanced cold-season warming in semi-arid regions

2012 ◽  
Vol 12 (2) ◽  
pp. 4627-4653 ◽  
Author(s):  
J. Huang ◽  
X. Guan ◽  
F. Ji
Keyword(s):  
North America ◽  
Land Surface ◽  
Temperature Increase ◽  
Arid Regions ◽  
Surface Air Temperature ◽  
Warming Trend ◽  
Cold Season ◽  
Arid Areas ◽  
Temperature Trends ◽  
Semi Arid

Abstract. This study examined surface air temperature trends over global land from 1901–2009. It is found that the warming trend was particularly enhanced, in the boreal cold season (November to March) over semi-arid regions (with precipitation of 200–600 mm yr−1), showing a temperature increase of 1.53 °C as compared to the global annual mean temperature increase of 1.13 °C over land. In mid-latitude semi-arid areas of Europe, Asia, and North America, temperatures in the cold season increased by 1.41, 2.42, and 1.5 °C, respectively. The semi-arid regions contribute 44.46% to global annual-mean land-surface temperature trend. The mid-latitude semi-arid regions in the Northern Hemisphere accounting contribute by 27.0% of the total, with the mid-latitude semi-arid areas in Europe, Asia, and North America accounting for 6.29%, 13.81%, and 6.85%, respectively. Such enhanced semi-arid warming (ESAW) may cause these regions to become drier and warmer.

scholarly journals Spatial variations in the warming trend and the transition to more severe weather in midlatitudes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Francisco Estrada ◽  
Dukpa Kim ◽  
Pierre Perron
Keyword(s):  
Radiative Forcing ◽  
Warming Trend ◽  
Severe Weather ◽  
Montreal Protocol ◽  
The Arctic ◽  
Extreme Weather Events ◽  
Jet Stream ◽  
Atmospheric Blocking ◽  
Regional Warming ◽  
Weather Events

AbstractDue to various feedback processes called Arctic amplification, the high-latitudes’ response to increases in radiative forcing is much larger than elsewhere in the world, with a warming more than twice the global average. Since the 1990’s, this rapid warming of the Arctic was accompanied by no-warming or cooling over midlatitudes in the Northern Hemisphere in winter (the hiatus). The decrease in the thermal contrast between Arctic and midlatitudes has been connected to extreme weather events in midlatitudes via, e.g., shifts in the jet stream towards the equator and increases in the probability of high-latitude atmospheric blocking. Here we present an observational attribution study showing the spatial structure of the response to changes in radiative forcing. The results also connect the hiatus with diminished contrast between temperatures over regions in the Arctic and midlatitudes. Recent changes in these regional warming trends are linked to international actions such as the Montreal Protocol, and illustrate how changes in radiative forcing can trigger unexpected responses from the climate system. The lesson for climate policy is that human intervention with the climate is already large enough that even if stabilization was attained, impacts from an adjusting climate are to be expected.

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