The Day of Seven Billion was proclaimed by the United Nations Population Fund (UNFPA) on 31 October 2011 as a historic milestone — the day the world's population reached seven billion people. And the world is on a steep growth curve for the rest of this century.

More than half (3.8 billion) of the population are Asians. Although South-East Asia comprises only 0.6 billion, it is growing fast — by almost 200 per cent between 1950 and 2000 — and is set to grow by another 50 per cent by 2050.

One of the most critical challenges facing a world with a population of seven billion is how to feed the roughly three billion people living below the poverty line in the slums of developing countries.

A 'perfect storm'

Scientists have warned that in the next 50 years, the world will consume twice as much food as it has since the beginning of agriculture 10,000 years ago. This is a startling statistic.

But thinking beyond food security to other crises facing the planet, the prospects look even more daunting. Asian agricultural scientist William D. Dar, director-general of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), spoke last month of a coming "perfect storm".  

This will be triggered by food shortages resulting from the population explosion, and aggravated by a combination of climate change (leading to warming temperatures and weather extremes including droughts and floods), land degradation, loss of biodiversity and increasing demand for energy.

To meet the challenge of feeding the half-billion or so poor people in South-East Asia and the Pacific, Dar and other agricultural scientists, including International Rice Research Institute (IRRI) director-general Robert Zeigler, have called for a second Green Revolution.

The first Green Revolution, led in Asia by IRRI in the 1960s and 1970s, prevented a predicted famine. Much of its success was due to the technological development of crops, such as semi-dwarf rice variety IR8, also known as the 'miracle rice' that produced 10 times the yield of traditional rice.

But despite its success, the Green Revolution had its share of critics. There were mistakes and side effects. Lessons must be learned if the countries of South-East Asia and the Pacific are to benefit from a second Green Revolution.

A greener revolution

The Green Revolution was criticised for focusing on a few high-yielding varieties that depend on irrigation, chemical fertilisers and pesticides. These practices harmed the environment and affected both agricultural and wild biodiversity. 

It also meant that farmers began to rely on just a few crop species. In India, for example, there were about 30,000 rice varieties before the Green Revolution. Today there are around 10 — the most productive types.

Mono-cropping has left the three staple crops of the Green Revolution — rice, maize and wheat — vulnerable to plant diseases that cannot be controlled by agrochemicals. It also led to concerns about the permanent loss of valuable genetic traits bred into traditional varieties over thousands of years.

To avoid repeating these mistakes, a second Green Revolution should include more than the staple crops that fed the world from the 1950s to the 1980s, and embrace dryland farming to grow crops such as sorghum, cassava and beans.

And it should harness South-East Asia's vast upland, rain-fed agricultural areas, not just the irrigated lowlands at the centre of food production decades ago. About 70 per cent of the land area of South-East Asia is rain-fed, and most of its poor people live in these areas.

Harnessing science

Agricultural science and technologies developed over the decades can contribute to the success of a second Green Revolution. The challenge is to increase production using less water, nutrients and land, and with lower environmental impact.

But food security also requires crops that can withstand extreme weather. For example, IRRI has developed a rice variety that can survive two weeks of complete submergence in water, and recently released to farmers in Bangladesh two drought-tolerant rice varieties, BRRI dhan56 and BRRI dhan57.  

And ICRISAT has developed and tested innovations in crop, soil and water management that can help farmers better adapt to the impacts of climate change. For example, it has shown that adapting the germplasm of sorghum — the dietary staple of more than 500 million people in rain-fed areas — can help maintain crop yields in warmer temperatures.

Scientific innovations are here to be harnessed to head off the looming 'perfect storm'. What is needed is the political will — from governments, foundations and international agencies — to jump-start a second, greener Green Revolution in the uplands.