1. Southern South American climate trends Inés Camilloni – Moira Doyle University of Buenos Aires Second AIACC Regional Workshop for Latin America and the Caribbean Buenos Aires, 24-27 August 2004 AIACC Project LA26: Impact of Global Change on the Coastal Areas of the Río de la Plata: Sea Level Rise and Meteorological Effects

2. Outline Temperature Temperature Rainfall Rainfall River discharges River discharges Surface circulation Surface circulation

3. Global annual temperature trends: 1976-2000 IPCC (2001)

4. Annual temperature trends in SE South America efecto urbano filtrado

5. Global annual rainfall trends: 1900-2000 IPCC (2001) SE South America:  23% Chile:  50%

6. Annual rainfall trends (mm/year): 1960-2000 The region shows increments in the annual rainfall between 10% and 40%. The increments in some regions of the Río de la Plata basin are between 200 and 300 mm in 40 years. IMPACTS

7. Impact of rainfall trends: displacement of the agricultural border 1950-69 1980-99 The agricultural border moved to the west. Annual rainfall (mm)

8. Impact of rainfall trends: changes in river discharges Río de la Plata basin Paraguay River Paraná River Uruguay River Salado River

9. Impact of rainfall trends: changes in river discharges Río de la Plata basin

10. Are streamflow trends really related to precipitation trends or due to land use change? Are streamflow trends really related to precipitation trends or due to land use change?

11. Berbery and Barros (2002) There is an amplification of the rainfall signal in the river flow that cannot be completely attributed to land use/cover changes. Averaged rainfall rates and river discharge for the Río de la Plata Basin for different timescale variability

12. Trends in extreme rainfall events Number of rainfall events larger than 100 mm in 2 days in central-east Argentina.

13. Annual frequency of extreme rainfall events Annual frequencies of rainfall events larger than 150 mm in 2 days for 1991/2002.

14. Changes in the annual frequency of extreme rainfall events Difference of annual frequencies of rainfall events larger than 150 mm in 2 days between 1959/1968 and 1991/2002.

15. % of rainfall due to Mesoscale Convective Complexes From Zipser

16. Changes in extreme monthly discharges Decadal number of cases with monthly discharge anomalies larger than 2 standard deviations

17. Changes in extreme monthly discharges Decadal number of cases with monthly discharge anomalies larger than 2 standard deviations

18. Rainfall trends in Chile La Serena Puerto Montt 29.5°S 71.1°W 41.4°S 73.05°W IMPACTS

19. Impact of rainfall trends: changes in river discharges Cuyo and Comahue regions

20. Changes in surface circulation 1951-19601991-2000 A A

21. PC1PC2 Monthly SLP patterns over South America Southward shift of the western border of the South Atlantic High since 1950.

22. Río de la Plata River mean level (mm) Buenos Aires: 1.7  0.1 mm/year D’Onofrio (2002)

23. Decadal distribution of “sudestadas” in the Río de la Plata Escobar et al (2004)

24. Concluding remarks: observed changes (1) ► ► Precipitation in Southeastern South America shows important positive trends during the last four decades with increases of up to 40% in some regions of northeastern Argentina  As a consequence, the agricultural border moved to the west  River discharges in the Río de la Plata basin increased as a result of the positive precipitation trends in northeastern Argentina, southern Brazil and Paraguay

25. Concluding remarks: observed changes (2)   The increase of extreme rainfall events in northeastern Argentina is important with a large number of damages  River discharges in Cuyo, Comahue and Patagonia show negative trends: impacts on regional and national economies  Displacement to the south of the western border of the South Atlantic High