Will Climate Change Cause Crop Shortfalls by 2020? Rising temperatures may slash yields for rice, wheat and corn throughout the developing world, according to a new report

Earth may be 2.4 degrees Celsius warmer by 2020, potentially triggering global scrambles for food supplies, according to a new analysis.

Work from the Universal Ecological Fund, the U.S. branch of Argentina-based nonprofit Fundación Ecológica Universal (FEU), sketches a somber portrait for world hunger by the end of the decade.

Rising temperatures will slash yields for rice, wheat and corn throughout the developing world, exacerbating food price volatility and increasing the number of undernourished people, the report warns.

It projects that food demand will substantially dwarf available supply.

The group drew upon existing climate and food production data from the Intergovernmental Panel on Climate Change (IPCC), the World Meteorological Organization and other U.N. agencies to draw its conclusions.

Chief among its findings, UEF said, is that if the planet continues on a business-as-usual path, temperatures may rise at least 2.4 degrees Celsius above preindustrial levels -- or 4.3 degrees Fahrenheit -- by 2020. Crossing a 2-degree-Celsius climate threshold is commonly considered dangerous.

The level of heat-trapping gases in the atmosphere, which was 284 parts per million in the preindustrial era, tallies more than 385 ppm today. By 2020, it could reach 490 ppm, cautions the report. Carbon concentrations that high are associated with a global temperature rise of 2.4 degrees Celsius, according to IPCC estimates.

Potential timing gapStill, it's not certain how quickly the planet would heat up if the planet had that concentration, said climate scientist Brenda Ekwurzel, with the Union of Concerned Scientists.

"If you look at Earth as an oven, by hitting 490 you turn the dial, but it could take a while for the oven to reach the temperature," she said.

Climate scientist Osvaldo Canziani served as the scientific adviser on the study, going over it "line by line," said Liliana Hisas, the executive director of the Universal Ecological Fund and author of the report. Canziani was unavailable for comment.

While not every part of the planet is expected to experience adverse effects of climate-linked impacts on agriculture, the report's numbers suggest that by 2020 there will be a 14 percent deficit between wheat production and demand, global rice production will stand at an 11 percent deficit, and there will be a 9 percent deficit in corn production. Soybeans, however, are expected to have a 5 percent surplus.

To meet the needs of a world that is expected to have an additional 890 million people by 2020, the global community would need to increase food production by about 13 percent, the report states.

Josef Schmidhuber, a senior policy analyst at the U.N. Food and Agriculture Organization, questioned some of the underlying assumptions for regional production figures and said that this UEF study also fails to consider other external factors that could affect these results.

"The only rationale for this to hold would be for climate change to have such a strong impact on the non-agricultural economy that people would lose purchasing power and thus would be so poor they couldn't afford the food they need to meet the requirements," Schmidhuber said. "Food security is much more than a production problem -- it reflects above all a lack of access to food and a lack of income," he said.

Schmidhuber contends that looking at food security purely in the context of the impacts of food production will lead to overstatements of hunger estimates.