Climate change has already cut into the global food supply and is fuelling wars and natural disasters, but governments are unprepared to protect those most at risk, according to a report from the UN's climate science panel.
The report is the first update in seven years from the UN's international panel of experts, which is charged with producing the definitive account of climate change.
In that time, climate change has ceased to be a distant threat and made an impact much closer to home, the report's authors say. "It's about people now," said Virginia Burkett, the chief scientist for global change at the US geological survey and one of the report's authors. "It's more relevant to the man on the street. It's more relevant to communities because the impacts are directly affecting people – not just butterflies and sea ice."
The scientists of the Intergovernmental Panel on Climate Change found evidence of climate change far beyond thawing Arctic permafrost and crumbling coral reefs – "on all continents and across the oceans".
But it was the finding that climate change could threaten global food security that caught the attention of government officials from 115 countries who reviewed the report. "All aspects of food security are potentially affected by climate change," the report said.
The scientists said there was enough evidence to say for certain that climate change is affecting food production on land and sea.
The rate of increase in crop yields is slowing – especially in wheat – raising doubts as to whether food production will keep up with the demand of a growing population. Changes in temperature and rainfall patterns could lead to food price rises of between 3% and 84% by 2050.
Other food sources are also under threat. Fish catches in some areas of the tropics are projected to fall by between 40% and 60%, according to the report.
The report also connected climate change to rising food prices and political instability, for instance the riots in Asia and Africa after food price shocks in 2008.