A critical question for agricultural production and food security is how water demand for staple crops will respond to climate and carbon dioxide (CO2) changes, especially in light of the expected increases in extreme heat exposure. To quantify the trade-offs between the effects of climate and CO2 on water demand, we use a ‘sink-strength’ model of demand which relies on the vapour-pressure deficit (VPD), incident radiation and the efficiencies of canopy-radiation use and canopy transpiration; the latter two are both dependent on CO2.

An important source of uncertainty in anticipating the effects of climate change on agriculture is limited understanding of crop responses to extremely high temperatures. This uncertainty partly reflects the relative lack of observations of crop behaviour in farmers’ fields under extreme heat. We used nine years of satellite measurements of wheat growth in northern India to monitor rates of wheat senescence following exposure to temperatures greater than 34 °C.

Efforts to anticipate how climate change will affect future food availability can benefit from understanding the impacts of changes to date. Here we show that in the cropping regions and growing seasons of most countries, with the important exception of the United States, temperature trends for 1980-2008 exceeded one standard deviation of historic year-to-year variability.

As efforts to mitigate climate change increase, there is a need to identify cost-effective ways to avoid emissions of greenhouse gases (GHGs). Agriculture is rightly recognized as a source of considerable emissions, with concomitant opportunities for mitigation.

Investments aimed at improving agricultural adaptation to climate change inevitably favor some crops and regions over others. An analysis of climate risks for crops in 12 food-insecure regions was conducted to identify adaptation priorities, based on statistical crop models and climate projections for 2030 from 20 general circulation models.