Climate and society in the recent environmental change in the Sahel Alessandra Giannini, IRI

1. Climate and society in the recent environmental change in the Sahel Alessandra Giannini, IRI alesall@iri.columbia.edu

2. Intersection of climate and society, predictability and sensitivity at global scale Ropelewski and Halpert 1987, 1989 Sachs et al, 2001 in Sci Am IRI mission: “We use a science-based approach to enhance society's capability to understand, anticipate and manage the impacts of climate in order to improve human welfare and the environment, especially in developing countries.”

3. Intersection of climate and society, predictability and sensitivity: the case of the Sahel Grey and Sadoff, World Bank 2005 IPCC AR4, Chapter 3 (Observations) I

4. Climate thread: oceans’ influence explains past persistent drought attribution of drought to emissions from industrialization projections of future change Time scales of climatic influence on livelihoods in Mali Adaptation is happening It is resilient? What role for climate science in global negotiations, in regional policy?

5. Giannini, A, R Saravanan, P Chang, 2003. Science, 320, 1027-1030 Oceans caused 20th century Sahel drought land surface-atmosphere interaction a positive feedback

6. Peaking out from the ivory tower: -- how does one get involved in ensuring that the knowledge generated in academia is translated into action that benefits society? -- dissonance between doom and gloom about global climate change and local action/people on the ground

7. Variability in Sahel rainfall (25% in obs, 21% in ens-mean) Giannini, A, R Saravanan, P Chang, 2005 in Clim. Dyn.

8. Giannini, A, R Saravanan, P Chang, 2003 in Science Variability in Sahel rainfall: separation of interdecadal and interannual time scales

9. How do different time scales impact society? “The climate sensitivity of food security in Mali” a collaboration between IRI and the UN World Food Programme (Giannini, Krishnamurthy, Cousin and Choularton)

10. The 2005 Comprehensive Food Security Vulnerability Analysis of Mali: a socio-economic survey of ~2000 households in ~200 villages

11. FEWSnet livelihood zones and climate annual mean rainfall from GPCP 1979-2007

12. Shifting 20th century climatologies Number of years out of 30 that it rained at least 450 mm during wet 1941-1970 and dry 1971-2000, and % hh who grow millet: a staple crop dry 1971-2000 wet 1941-1970

13. 2005 CFSVA of Mali: a rural survey • Of 2074 hh surveyed: • 1142 practiced agriculture and livestock raising • 566 agriculture, but not livestock raising • 275 livestock raising, but not agriculture • 91 neither activity • % hh by livelihood zone who practice… • agriculture only, livestock raising only, both activities… • Abdulai and Crole-Rees; Barrett et al 2001, in Food Pol.

14. The effect of the multi-decadal persistence of drought is most visible in the central/Sahelian region of Mali, in the structural loss of assets and alternative livelihoods that is exemplified by the reduced engagement in livestock raising [However, not shown here, the occasional drought in the southern/Soudanian region can cause conjunctural food insecurity if it affects the dominant cash crop (cotton)]

15. In the meantime, people did not wait around for the end of the world… In fact, the positive outcome in defining the cause of drought as local is that >> it empowers people to find local solutions Are these solutions valuable in the face of climate change? (Warmer temperatures, greater variability in rainfall, including its intensity, perhaps shorter rainy seasons…)

16. The re-greening of the Sahel “In Niger, Trees and Crops Turn Back the Desert” Lydia Polgreen, New York Times, 11 Feb 2007

17. Comparing the roles of people, development donors and climate in re-greening the Sahel (Stith, Giannini, del Corral, Adamo, de Sherbinin)

18. Trends in environmental indicators: 1981-2003 [Jan-Dec means] Normalized Difference Vegetation Index (NDVI) Precipitation Stith et al, in prep.

19. Measures of human influence Number of “development” interventions per administrative region Population density in 1990 [CIESIN] Stith et al, in prep.

20. Places where there is a significant trend in greenness that correlates with precipitation in the long-term, but not on interannual time scales Stith et al, in prep.

21. A multiplicity of narratives… Stith et al, in prep.

22. Soil&water conservation on the Thies plateau, Senegal June 2011

23. What do climate change models say about the Sahel? • Attribution • Projections

24. IPCC AR4 simulations of late 20th century climate change consistently show a decrease in Sahel precipitation and warming of the oceans more pronounced in the tropics and southern hemisphere Biasutti and Giannini 2006, in Geophys Res Lett See Biasutti 2013 in J Geophys Res for the CMIP5 update precipitation change surface temperature change

25. IPCC AR4 simulations coherence of late 20th century response in the Sahel (l.h.s.) compared to 21st century projections (r.h.s.) Biasutti and Giannini 2006, in Geophys Res Lett

26. The relative roles of the Atlantic and Indian Oceans green – Sahel rainfall blue – north Atlantic SST (minus global mean) red – equatorial Indian Ocean SST (with sign reversed)

27. Sulfate aerosols reduced 20th century warming of the North compared to the South Atlantic Observations Multi-decadal Oscillation “Trend” Chang, Chiang et al 2010, in J Climate

28. Mechanisms to connect dynamics of variability and change: • Indian Ocean/warming of the tropical oceans •  controls vertical stability •  related to frequency of daily rainfall? • Atlantic Ocean/ •  controls moisture supply •  related to intensity of daily rainfall?

29. Models say that if the subtropical North Atlantic warms up more than the global tropics, then the Sahel could get wetter… Future: Yellow: mid-21st (A1B) – end 20th Red: end 21st – end 20th Past Green: end 20th century – pre-Industrial Blue: end – beginning 20th century

30. Oceanic influence Explains persistence of drought in the Sahel in the 1970s and 1980s, and partial recovery since Implicates the emissions of greenhouse gases and aerosols in the late 20th century evolution of climate in the Sahel, including persistent drought Can be used to make sense of model projections of future precipitation change

31. Climate thread: oceans’ influence explains past persistent drought attribution of drought to emissions from industrialization projections of future change Time scales of climatic influence on livelihoods in Mali Adaptation is happening It is resilient? What role for climate science in global negotiations, in regional policy?