"The impacts are already evident in many places in the world," David Lobell, a professor at Stanford University said. "It is not something that is [only] going to happen in the future."
Cultivation of wheat, corn and other grain crops have already suffered because of drought conditions and other climate change indicators.
"Almost everywhere you see the warming effects have a negative affect on wheat and there is a similar story for corn as well. These are not yet enormous effects but they show clearly that the trends are big enough to be important," Lobell stressed.
Scientists also warn that if something is not done soon to thwart climate change conditions the world will face "severe, pervasive and irreversible"consequences of dwindling food supplies and lower agricultural yields.
"We can't continue to ignore the stark warnings of the catastrophic consequences of climate change on the lives and livelihoods of people across the planet," Friends of the Earth's executive director, Andy Atkins, said in response to the latest UN report, urging world leaders to work together to find a solution.
"Giant strides are urgently needed to tackle the challenges we face, but all we get is tiny steps, excuses and delays from most of the politicians that are supposed to represent our interests."