1. MERGE for GAC 19-20 May 2010 Climate Scenarios for Decisions and Policies Markku Rummukainen Lund University Centre for Environmental and Climate research Markku.Rummukainen@cec.lu.se

2. MERGE for GAC 19-20 May 2010 ”Terra incognita” 2 Then Now Soon ? ? ?

3. MERGE for GAC 19-20 May 2010 Visibleearth.nasa.gov

4. MERGE for GAC 19-20 May 2010 C C 1. Read the field with PE 0 and distribute the error code C ierr = 0 if( mype.eq.0 ) then C call gread(lun,type,param,alev, X w,nx_grib,ny_grib,ierr,idum) C endif ! mype call broadca(0,'i',1,ierr,rdum,ldum,cdum) if(ierr.ne.0) return C C 2. Send to all processors C call broadca(0,'r', + nx_grib*ny_grib, + idum,w,ldum,cdum) C C 3. Do the interpolation C do j=1,ny_local do i=1,nx_local ii = i_f(i,j) jj = j_f(i,j) ckw 040301 iip = 1+mod(ii,nx_grib) cuh 050608 jjp = min(jj+1,ny_grib) f(i,j) = (1.-w_x_f(i,j))*(1.-w_y_f(i,j))*w(ii,jj) + x (1.-w_x_f(i,j))*w_y_f(i,j) *w(ii,jjp) + x w_x_f(i,j)*(1.-w_y_f(i,j))*w(iip,jj) + x w_x_f(i,j)*w_y_f(i,j) *w(iip,jjp) end do return c end

5. MERGE for GAC 19-20 May 2010 Triolith supercomputer. Photo: Göran Billeson. www.liu.se

6. MERGE for GAC 19-20 May 2010 We know that It’s getting warmer, etc. We are the cause The future is not set in stone, yet SMHI bildbank

7. MERGE for GAC 19-20 May 2010 How much climate change? Climate sensitivity Carbon cycle / climate Emissions

8. MERGE for GAC 19-20 May 2010 A ”thousand” alternative futures Fuss et al. 2014 Net carbon dioxide emittions Gt CO 2/ yr Year

9. MERGE for GAC 19-20 May 2010 Climate change: changing & changed climate Year ºC After IPCC 2013 12 10 8 6 4 2 0 Business as Usual Ambitious mitigation

10. MERGE for GAC 19-20 May 2010 Regional differences in changes E.g., Sea level rise towards 2100 under cont’d large emissions IPCC 2013

11. MERGE for GAC 19-20 May 2010 2ºC2ºC2ºC2ºC 3ºC3ºC3ºC3ºC 4ºC4ºC4ºC4ºC 6ºC6ºC6ºC6ºC

12. Climate models useful for finding out about How much will climate change (for given emissions)? What are the global, regional and local impacts? What is the possibility for tipping points? Photos: M. Rummukainen

13. MERGE for GAC 19-20 May 2010 Climate scenarios provide for ”climate proofing” Adaptation Mitigation Residual impacts Photos: M. Rummukainen, sxz.hu, Stockholm In essence, proofing future development

14. MERGE for GAC 19-20 May 2010 Image © Risager, torebda.se, svensktvatten.se, http://www.mynewsdesk.com/se/stockholm_international_water_institute Urban areas Physical infrastructure, e.g. sewer systems, harbours, roads and railways, … Coastal erosion Water resources Irrigation Biodiversity, Nature conservation Power grids Laws and regulations Natural catastrophes, e.g. landslides, flooding Technology change and Innovation Consumption patterns Regional planning Traffic and Transports Renewables Insurance mechanisms Agriculture, Forestry Investments Sustainable Development …