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

Global surface temperature in the CLE and MFR scenarios

Surface temperature change (S2-S1) between 2046-2070 & 1990-2014

Surface temperature change in the CLE scenario between 1990-2014 & 2046-2070

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

Thank you for your attention

Change in surface temperature

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.