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Climate and agriculture outlook 07/08 . Johan van den Berg SANTAM AGRI 26 October 2007 AMT Pretoria . Rainfall (mm) January - March. 2007. 1992. Rainfall deviation (%) from average for the January to March period 2007 vs 1992 . 2007. 1992. 2007. 1992. 2007. 1992. 2007. 1992. 2007.
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Climate and agriculture outlook 07/08 Johan van den Berg SANTAM AGRI 26 October 2007 AMT Pretoria
Rainfall (mm) January - March 2007 1992
Rainfall deviation (%) from average for the January to March period 2007 vs 1992 2007 1992 2007 1992 2007 1992 2007 1992 2007 1992 2007 1992 2007 1992 2007 1992 2007 1992 2007 1992
January to June 2007 Lowest rainfall on record since 1915
Rainfall Deviation from average January – June 2007 (100% = average)
Rainfall deviation from average (%) 1 April – 30 September 2007
Rainfall deviation from average (%) Western Cape 1 April – 30 September 2007
El Nino Indian Ocean
Tropical cyclone H L Cyclone Water = 18-28oC Water = 10-12oC
moderate strong
Bottom line Strongest La Nina development with associated normal or cooler than normal Indian Ocean in the past few decades
Probability (%) for at least normal rainfall November December January February March April
Bothaville: Probability (%) for at least 20mm/10 day period 2007/08 Average
Grootfontein (Namibia): Probability (%) for at least 20mm/10 day period 2007/08 Average
RSA: Cumulative rainfall deviation (mm) from average (past 30 years)
RSA: Cumulative rainfall deviation (mm) from average (past 10 years)
The BIG question: Is it a result of climate change or can we expect somewhere in future to catch up ?
USA maize yields deviation (%) (detrended)
USA maize yields deviation (%) Moderate La Nina and strongLa Nina years
USA maize yields deviation (%) Moderate El Nino and strong El Nino years
RSA maize yields deviation (%) (detrended)
RSA maize yields deviation (%) (detrended) Irrigation
USA maize yields deviation (%) (detrended)
Summary • Recent past 1 - 3 decades “abnormal” dry • Recovery to take place or permanent change due to global warming? • La Nina event for 2007/08 to last until at least winter of 2008 • Favourable rainfall – central to western parts
Summary 6. High probability for below normal rainfall for USA summer crops