Washington, Sep 14 (IANS) With water reserves starting to run low in key grain production areas such as India and China, a senior UN official has called for a second 'Green Revolution' to feed the world's growing population.

A 100 million people faced forced migration as a consequence of advancing desertification and soil degradation, Jacques Diouf, director-general of the UN Food and Agricultural Organisation noted while giving the call.

"In the next few decades, a major international effort is needed to feed the world when the population soars from six to nine billion," Diouf told a meeting of the World Affairs Council of Northern California in San Francisco. "We might call it a second Green Revolution."

The original Green Revolution of the 1950s and 60s doubled world food production by bringing the power of science to agriculture, but "relied on the lavish use of inputs such as water, fertiliser and pesticides", Diouf said.

"The task ahead may well prove harder," he cautioned.

"We not only need to grow an extra one billion tonnes of cereals a year by 2050 - within the lifetimes of our children and grandchildren - but do so from a diminishing resource base of land and water in many of the world's regions, and in an environment increasingly threatened by global warming and climate change.

"The new Green Revolution will be less about introducing new, high-performance varieties of wheat or rice, important as they are, and much more about making wiser and more efficient use of the natural resources available to us," Diouf said.