“Agriculture is extremely vulnerable to climate changes,” notes a new study from the International Food Policy Research Institute (IFPRI) that looks at how climate change will affect food production around the world by 2050.

“Developing countries are likely to be hardest hit by climate change and will suffer bigger declines in crop yields,” said Gerald Nelson, lead author of the study and an IFPRI research fellow, in a conference call with journalists on Tuesday.

Temperatures will rise to “intolerable levels” for some plants, he noted, while higher temperatures will encourage proliferation of weeds, insects, and crop diseases.

And those negatives won’t necessarily be offset by an increase in carbon dioxide concentrations. In the laboratory, plants generally respond favorably to higher levels of CO2, but the story is different in farm fields. There, higher concentrations can cause more insect damage.