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Past and future aerosol emission reductions and their impact on Arctic climate
Hansson, H.-C., Acosta Navarro, J. C. & Varma, V, Riipinen, I., Seland, Ø., Kirkevåg, A., Struthers, H.,
Iversen, T., Ekman, A. M. L.
Stockholm University, Sweden and Norwegian Meteorological Institute, Oslo, Norway
Has European air quality measures affected the climate in Europe or elsewhere?
CLRTAP30% reduction agreement
Emission scenarios
The scenario “Fixed EU emissions” assume that SO2 emissions from EU has been constant since 1980. Other emissions as they have been.
The scenario “Historic emissions” is the emissions from that EU and all other countries have had since 1980 and forward
EU SO2 emissions
Global SO2 emissions
Effect on Aerosol Optical Depth“Historic” minus “Fixed EU emissions” scenario
Dotted indicate significant (95%) effect
Effect on Cloud Droplet Number“Historic” minus “Fixed EU emissions” scenario
Dotted indicate significant (95%) effect
Effect on Net Top of the Atmosphere Radiation (Long + Short Wave)
“Historic” minus “Fixed EU emissions” scenario
Dotted indicate significant (95%) effect
Effect on Surface Temperature“Historic” minus “Fixed EU emissions” scenario
Dotted indicate significant (95%) effect
So
• Major air quality measures can have an effect on the large scale atmospheric circulation causing significant climate changes.
• This climate change do not have to effect the regions where the emission changes occurred
• It can effect totally different regions.
CLE: Current Legislation Emissions(Only minor changes)
MFR: Maximum Feasible Reduction (About 70-80% decrease of emissions)
CO2 and CH4 according to RCP 4.5 (CO2 peak before 2100 at about 2*CO2 and CH4 about unchanged
The Conclusions • European emission reductions have been
responsible for a significant fraction of the recent Arctic warming.
• Future global reduction will have a significant influence on the Arctic climate.
• HOWEVER CO2 DOMINATE the Arctic climate change.
• The climate change will most likely in all emission scenarios continue to have a dramatic influence on the Arctic
Result!!
The aerosol-induced positive radiative flux perturbation at the top of the atmosphere over mid-latitudes has been compensated by an increased poleward dry-static heat transport.
This response is contrary to the decrease in poleward dry-static heat transport associated with increased atmospheric concentrations of CO2.
The results reveal a unique inherent link between air quality regulations in the Northern hemisphere, general circulation and Arctic climate.