UN ECA - CILSS – ACMAD - IRI Conference on Reduction of vulnerability of West Africa to climate change Ouagadougou, January 24-27 2007 mate scientist's perspective on recent environmental tre in the Sahel: a model for future change? Alessandra Giannini IRI for Climate and Society (IRI) The Earth Institute at Columbia University
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UN ECA - CILSS – ACMAD - IRI Conference on Reduction of vulnerability of West Africa to climate change Ouagadougou, January 24-27 2007 A climate scientist's.
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UN ECA - CILSS – ACMAD - IRIConference on Reduction of vulnerability of West Africa to climate change
Ouagadougou, January 24-27 2007
A climate scientist's perspective on recent environmental trendsin the Sahel: a model for future change?
Alessandra GianniniIRI for Climate and Society (IRI)
The Earth Institute at Columbia University
Outline – past, present and future of climate in the Sahel
1. oceanic forcing dominant in late 20th century droughts- what role for land-atmosphere interaction?
2. late 20th century response to anthropogenic forcings - roles of GreenHouse Gases and (sulfate) aerosols
3. why the uncertainty in projections of future change?- mechanisms of monsoon change under climate change
r = 0.60
A. Giannini, R. Saravanan and P. Chang, 2003. Science, 302, 1027-1030Also see e.g. Bader and Latif, 2003 (GRL); Lu and Delworth, 2005 (GRL);Tippett, 2006 (GRL)
land-atmosphere interaction: is it a positive feedback?(soil moisture, vegetation, dust..., evaporation, cloud cover...)
NASA/GISS analysis of surface temp – linear trend 1950-2000Hansen et al. 1999 (J. Geophys. Res.)
regression of NASA/NSIPP1 Sahel PC and sfc tempGiannini et al. 2003, 2005
IPCC 4AR: end 20th century – PreIndustrial sfc temp differenceBiasutti and Giannini 2006 (GRL)
late 20th century surface temperature changes
19 Coupled GCMs XX-PI Changes
Biasutti and Giannini, GRL 2006
IPCC 4AR simulations – late 20th century climate change
Biasutti and Giannini, 2006 (GRL)
Sahel climate change20th century 21st century
19 Coupled GCM (IPCC 4AR):recent and future temperature
changes
A1B (end 21st)- end 20th
end 20th- PreInd
CONCLUSIONS (climate science)
● African climate variability and change are inextricably tied to variations and trends in the global climate system:
-->> recent trends in the global oceans and in continental precipitation can in part be ascribed to anthropogenic forcings
-->> drought in the Sahel was forced by a warming of the oceans, in no negligible part due to GHG and aerosol forcing
“Farmers freed of blame for Sahel drought” in http://www.scidev.net/
CONCLUSIONS (climate science informing policy)
● Climate change is already here - the recent climate shift in the Sahel is a prime example of potential changes to come, as the global climate system responds to anthropogenic forcings
-->> regional institutions/CILSS have an opportunity to take advantage of the lessons learned from managing the climate shift of the last ~30 years
-->> harmonization of desertification and climate change issues is overdue!
CONCLUSIONS (climate science informing practice - climate risk management)
● collaborate on climate science● improve (two-way) communication
-->> between climate scientists and policymakers-->> between climate scientists and stakeholders in sectors vulnerable to climate