1. Observed changes in climatic variables relevant for agricultural production during 1930-2000 in the Pampas region of Argentina, Brazil and Uruguay (AIACC Project No. LA27) Walter E. Baethgen (IRI Columbia University-INIA, Uruguay) Agustin Gimenez (INIA, Uruguay) Graciela Magrin (INTA-Argentina) Maria I. Travasso (INTA-Argentina) Gilberto Cunha (EMBRAPA, Brasil) Mauricio Fernandes (EMBRAPA, Brasil)

2. Objectives Explore changes in the last 70-100 years observed in climate variables that are relevant for agricultural production Establish the basis for one of the methods used in our project to create climate change scenarios: project changes observed in the last 70-100 years to the next 10-20 years using a weather generator (G. Magrin’s presentation)

3. Methods Linear regression of mean trimester rainfall and temperatures for the entire available period (1930 – 2000) Stat significance using parametric and non-parametric (Kendall) tests Plot slopes using a contouring and surface mapping program (Surfer) to study spatial distribution of changes Expected Result Annual mean changes of the trimester means for Rainfall, T Max, T Min in the entire period (1930 - 2000) Remaining Question: Were changes uniform throughout the entire period? Time

4. Methods (2) Compare rainfall and temperature means for different periods: 10-year periods: 1930-40, 1940-50, …, 1990-2000 20-year periods: 1930-50, 1940-60, …, 1980-2000 30-year periods: 1930-1960 vs 1970-2000

5. RESULTS Changes in Rainfall (mm Trimester / year) Linear regression Analysis

6. Changes in Rainfall (mm Trimester / year)

18. Changes in Rainfall (mm Trimester / year) Linear regression Analysis Significant Slopes (P<0.10)

19. Changes in Rainfall (mm Trimester / year)

31. Summary by Trimester

32. Fall

33. Winter

34. Spring

35. Summer

36. Comparing two Periods: 1930-1960 vs 1970-2000

39. Changes in Temperatures Mean monthly T Max Mean monthly T Min Regression Analysis

40. JFM T Min MJJ JFM JJA T Max

41. Comparing two Periods: 1930-1960 vs 1970-2000

42. T Max: 1931-1960 vs 1970-2000 (Summer 1931-1960)

43. T Max: 1931-1960 vs 1970-2000 (Summer 1970-2000)

44. T Min: 1931-1960 vs 1970-2000 (Winter 1931-1960)

45. T Min: 1931-1960 vs 1970-2000 (Winter 1970-2000)

46. T Min: 1931-1960 vs 1970-2000 (Summer 1931-1960)

47. T Min: 1931-1960 vs 1970-2000 (Summer 1970-2000)

48. Relevance for Agricultural Production: Frost Regime

49. UY = Estanzuela AR = Pergamino

50. Changes in frost regime estimated with regressions (1930-2000)

51. 2000 compared to 1930: Frost period starts later and ends earlier Less number of frosts in the frost period Mean temperature of frosts is higher

52. Changes in absolute and in mean TMax and Tmin Estimated with Regressions (1930 – 2000)

53. Changes in absolute and in mean TMax and Tmin Estimated with Regressions (1930 – 2000) 2000 compared to 1930: Absolute TMax and Mean TMax are lower Absolute TMin and Mean TMin are higher

54. Reported Changes in Means Changes in Variability?

56. 7+, 2-, 1= 3+, 3-, 4= 4+, 4-, 2= 5+, 5=

57. Conclusions Increased Rainfall in Spring and Summer Better for pastures, summer crops but animal / crop diseases? pests? (M. Fernandes’ presentation) Increased Rainfall Variability in Summer (?) (higher risk) Decreased Mean T Max (Spring and Summer) Increased Mean T Min (all year) Shorter frost period (first – last dates) Less number of days with frost Frosts became less severe (Temp is higher)