Climate Change Scenarios

For our soil C stock simulations, we modified the current climatic data (Table 9.1) measured at the study area, using Tyndall Center predictions (TYN CY 3.0 data set for Brazil available at www.cru.uea.ac.uk/~timm/grid/table.html). Details on the TYN SC 3.0 data set are fully reported by Mitchell et al. (2003). Briefly, the TYN CY 3.0 data set

Table 9.1 Actual and Predicted Weather Data for Nova Vida Ranch

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Table 9.1 Actual and Predicted Weather Data for Nova Vida Ranch

Actual Data

HadCM3-A1F1

DOE PCM-B1

Maximum

Minimum

Maximum

Minimum

Maximum

Minimum

Precipitation

Temperature

Temperature

Precipitation

Temperature

Temperature

Precipitation

Temperature

Temperature

Month

(cm)

(°C)

(°C)

(cm)

(°C)

(°C)

(cm)

(°C)

(°C)

January

38.5

34.0

18.7

33.0

40.1

12.6

38.4

35.1

17.6

February

39.2

27.6

15.3

35.5

33.2

9.7

39.1

28.6

14.3

March

33.3

27.0

15.4

28.3

33.0

9.4

33.2

28.1

14.3

April

17.4

31.4

23.6

14.5

38.0

17.0

17.3

32.7

22.3

May

17.7

32.4

19.6

14.9

39.6

12.4

17.7

33.7

18.3

June

5.8

32.9

18.9

3.2

40.2

11.6

5.8

34.3

17.5

July

3.4

33.9

25.3

1.8

41.3

17.9

3.3

35.2

24.0

August

3.1

32.9

24.1

1.5

39.9

17.1

3.1

34.4

22.6

September

11.1

32.2

23.5

8.3

39.0

16.7

11.0

33.5

22.2

October

16.2

28.0

18.3

11.3

35.0

11.3

16.1

29.5

16.8

November

29.7

31.9

20.7

23.3

38.8

13.8

29.6

33.2

19.4

December

33.0

34.3

24.3

26.8

40.9

17.7

32.9

35.5

Hi c

Note: Actual data derive from local meteorlogical station, and predicted data derive from Tyndall Center calculations.

Note: Actual data derive from local meteorlogical station, and predicted data derive from Tyndall Center calculations.

Kj vo comprises predicted climate for the 2001-2100 period. There are five climatic variables available: cloud cover, diurnal temperature range, precipitation, temperature, and vapor pressure. There are 16 climate change scenarios that comprise all permutations of four GCM models (GCMM2, CSIRO mk 2, DOE PCM, and HadCM3, used by the IPCC [2001]) with four contrasting emissions scenarios (A1F1, A2, B2, B1) used by the IPCC Special Report on Emission Scenarios (SRES) (IPCC, 2001). This study is based on results from the HadCM3 model combined with the A1F1 SRES scenario (HadCM3-A1F1), and DOE PCM model with the B1 scenario (DOE PCM-B1), covering the maximum range in temperature and precipitation changes applied to actual data registered for the Nova Vida region.

Data from the Tyndall Center predicted that scenario HadCM3-A1F1 would cause an increase of 6.7°C in annual mean temperature and a decrease of 461 mm in annual mean precipitation. Scenario DOE PCM-B1 indicated smaller variations in annual temperature and precipitation compared to the former scenario, that is, an average annual mean temperature increase of only 1.3°C and a 50 mm increase in annual mean precipitation (Mitchell et al., 2003). It is important to emphasize that modifications made on actual data (Table 9.1) were performed using specific simulated results of temperature and precipitation for each month of the year (i.e., we did not spread simulated climatic differences uniformly throughout the year). Preserving the monthly differences in temperature and precipitation is important in areas where there are marked differences between wet and dry seasons, which is the case for our study area.

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