Southern South Southern South American climate trendsAmerican climate trends

Inés Camilloni – Moira DoyleInés Camilloni – Moira DoyleUniversity of Buenos AiresUniversity 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

OutlineOutline

TemperatureTemperature

RainfallRainfall

River dischargesRiver discharges

Surface circulationSurface circulation

Global annual temperature trends: Global annual temperature trends: 1976-20001976-2000

IPCC (2001)

Annual temperature trends in SE South Annual temperature trends in SE South AmericaAmerica

efecto urbano filtrado

Global annual rainfall trends: 1900-Global annual rainfall trends: 1900-20002000

IPCC (2001)

SE South America: 23%Chile: 50%

Annual rainfall trends (mm/year): 1960-Annual rainfall trends (mm/year): 1960-20002000

- 70 - 65 - 60 - 55 - 50 - 45 - 40

Tendencia AN UAL - O C -SE (Sum a Pesados)

- 40

- 35

- 30

- 25

- 20

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

Impact of rainfall trends: Impact of rainfall trends: displacement of the agricultural displacement of the agricultural

border border

- 7 5 - 7 0 - 6 5 - 6 0 - 5 5

- 5 5

- 5 0

- 4 5

- 4 0

- 3 5

- 3 0

- 2 5

- 2 0

1950-691980-99 The agricultural

border moved to the west.

Annual rainfall (mm)

Impact of rainfall trends: changes in river Impact of rainfall trends: changes in river dischargesdischarges

Río de la Plata basinRío de la Plata basin

Paraguay RiverParaná River

Uruguay RiverSalado River

Impact of rainfall trends: changes in river Impact of rainfall trends: changes in river dischargesdischarges

Río de la Plata basinRío de la Plata basin

Paraná River - Corrientes

annu

al d

isch

arge

(m

3 /s)

0

5000

10000

15000

20000

25000

30000

35000

40000

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Uruguay River- Paso de los Libres

annu

al d

isch

arge

(m3 /s

)

0

2000

4000

6000

8000

10000

12000

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Salado River - RP 70

annu

al d

isch

arge

(m3 /s

)

0

100

200

300

400

500

600

700

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Paraguay River - Puerto Bermejo

annu

al d

isch

arge

(m

3 /s)

0

2000

4000

6000

8000

10000

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Are Are streamflow streamflow

trendstrends really related really related

toto precipitation trendsprecipitation trends

or due toor due to land use land use

change?change?

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

Trends in extreme rainfall eventsTrends in extreme rainfall events

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

Annual frequency of extreme rainfall Annual frequency of extreme rainfall eventsevents

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

Changes in the annual frequency of Changes in the annual frequency of extreme rainfall eventsextreme rainfall events

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

% of rainfall due to Mesoscale Convective % of rainfall due to Mesoscale Convective ComplexesComplexes

From Zipser

Changes in extreme monthly Changes in extreme monthly dischargesdischarges

Decadal number of cases with monthly discharge anomalieslarger than 2 standard deviations

Paraná River - Corrientes

21 1

01 1

0

12

10

0

2

4

6

8

10

12

14

1910-19 1920-29 1930-39 1940-49 1950-59 1960-69 1970-79 1980-89 1990-99

Uruguay River - Paso de los Libres

5 5 54

34

5

7

10

0

2

4

6

8

10

12

14

1910-19 1920-29 1930-39 1940-49 1950-59 1960-69 1970-79 1980-89 1990-99

Changes in extreme monthly Changes in extreme monthly dischargesdischarges

Decadal number of cases with monthly discharge anomalieslarger than 2 standard deviations

Rainfall trends in ChileRainfall trends in Chile

La Serena

Puerto Montt

29.5°S 71.1°W

41.4°S 73.05°W

IMPACTS

Atuel River - La Angostura

annu

al d

isch

arge

(m

3 /s)

0

20

40

60

80

100

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

San Juan River - Km 47.3

annu

al d

isch

arge

(m

3 /s)

0

50

100

150

200

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Neuquén River - Paso de Indios

annu

al d

isch

arge

(m

3 /s)

0

100

200

300

400

500

600

700

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Colorado River - Pichi Mahuida

annu

al d

isch

arge

(m

3 /s)

0

100

200

300

400

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Impact of rainfall trends: changes in river Impact of rainfall trends: changes in river dischargesdischarges

Cuyo and Comahue regionsCuyo and Comahue regions

-75 -70 -65 -60 -55 -50 -45-55

-50

-45

-40

-35

-30

-25

-20

Changes in surface circulationChanges in surface circulation

1951-1960 1991-2000

AA

- 6 5 - 6 0 - 5 5 - 5 0 - 4 5

- 4 5

- 4 0

- 3 5

- 3 0

- 2 5

- 2 0

- 6 5 - 6 0 - 5 5 - 5 0 - 4 5

- 4 5

- 4 0

- 3 5

- 3 0

- 2 5

- 2 0

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1962

1964

1966

1968

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

FL1 FL2 Lineal (FL1) Lineal (FL2)

PC1 PC2

Monthly SLP patterns over South Monthly SLP patterns over South AmericaAmerica

Southward shift of the western border of the South Atlantic High since 1950.

RRío de la Plata River mean level ío de la Plata River mean level (mm)(mm)

600

650

700

750

800

850

900

950

1000

1050

1900 1920 1940 1960 1980 2000 2020

Buenos Aires: 1.7 0.1 mm/year

D’Onofrio (2002)

Decadal distribution of Decadal distribution of “sudestadas” in the Río de la Plata“sudestadas” in the Río de la Plata

Escobar et al (2004)

Concluding remarks: observed changes Concluding remarks: observed changes (1)(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

Concluding remarks: observed changes Concluding remarks: observed changes (2)(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