Speaking ahead of a UN conference on desertification that opens next week in Madrid, the head of the WMO's Agricultural Meteorology Division, M. Mannava Sivakumar, warned that the resulting shrinkage in arable land could have severe consequences on food resources.

"There has been an increasing trend in extreme events observed during the last 50 years, particularly heavy precipitation events, hot days, hot nights and heat waves," Sivakumar said.

"The combination of these events can lead to land degradation and subsequently desertification," he said, pointing to a fall of between 40 and 60 percent in corn production in Zimbabwe, Swaziland and Lesotho.

"Only about 11 percent of the global land surface can be considered as prime land, which must feed a world population of 6.3 billion today and the 8.2 billion expected in the year 2020," he added.

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