One of the biggest concerns of global warming is its effect on agriculture. How will higher temperatures and concentrations of carbon dioxide (CO 2) affect agricultural production? What are the implications for feeding the billions of poor who rely on small-scale and subsistence farming? And what can we do to mitigate the impacts?

The International Rice Research Institute (IRRI) has a long history of studying the effect of climate on rice. The first experiment on temperature effects was conducted in 1961, the year after IRRI's inception. Remarkably, the first work on high CO 2 concentrations' affect on rice plants was performed in 1971, long before climate change became known to a broader audience. Likewise, the first workshop dealing with climate and rice dates back to 1974.

In 2007, IRRI established the Rice and Climate Change Consortium to assess the direct and indirect consequences of global warming for rice production, develop strategies and technologies to adapt rice to changing conditions, and explore crop-management practices that reduce greenhouse gas emissions under intensive production.

In the initial phase, the focus is on improving the resilience of rice to heat stress. IRRI is establishing monitoring sites to test the effects of emerging crop-management trends, such as diversification from double cropping of rice to rice-maize rotation, that will alter crops' budgets of carbon and nitrogen and so affect greenhouse gas emissions. Data gathered from these sites will be used to develop predictive models and guide future research.

The effect of higher atmospheric CO 2 concentrations and temperatures on rice yields is uncertain. Crop modeling at IRRI has determined that, as a rule, for every increase in CO 2 concentration of 75 parts per million, rice yields will increase by half a ton per hectare. Conversely, for every 1°C increase in temperature, yields will decrease by 0.6 tons per hectare. However, nobody has studied the interactions between CO 2 and temperature under controlled, realistic field conditions. The technology to do this is now available. If funding can be found, IRRI hopes to develop an experimental system in which both CO 2 and temperature can be controlled in rice fields.

A lot of genetic variation exists across varieties of cultivated rice and its wild relatives, supporting optimism that IRRI will be able to develop new varieties that can cope with higher temperatures. Scientists are also confident that the resilience of rice production systems to climate extremes, such as floods and droughts, can be improved within certain limits.

While IRRI sees plant breeding at the heart of efforts to safeguard rice production, the efficiency of adaptive measures can be increased significantly by other efforts, including

• molecular marker techniques to speed up the breeding process;
• geographic analysis of vulnerable regions, where the rice crop is already experiencing critical temperature levels;
• regional climate modeling to identify future tilting points affecting rice production (temperatures or CO 2 levels, for example, above which major yield losses are experienced); and
• site-specific adjustment in crop management, such as shifting planting dates and improved water management.

The envisaged adaptation of rice production to climate change will require substantial funds to support vigorous and concerted efforts by national and international research institutions.