New varieties of "heat-beating" beans, bred to be climate-proof, could help feed the globe's poorest inhabitants faced with the threat global warming presents to agriculture, researchers say.

Thirty new varieties of beans, created by the global agricultural research group CGIAR, offer hope to farmers in developing nations growing beans, often called the "meat of the poor" as they provide a vital source of protein for some 400 million people in the developing world.

The new beans have been bred out of concern that global warming could reduce the areas suitable for current bean crops by 50 percent by 2050, the researchers say, since most existing bean crops are very sensitive to excessive heat.

"Small farmers around the world are living on the edge even during the best situation," says senior bean researcher Steve Beebe of the International Center for Tropical Agriculture.

"Climate change will force many to go hungry, or throw in the towel, sell their land and move into urban slums if they don't get support."

The new bean types, or lines as plant breeders call them, could keep millions of people in bean-dependent Africa and Latin America fed, the researchers say. "We confirmed that 30 heat-tolerant lines are productive even with night-time temperatures above 22 degrees Celsius (about 72 degrees Fahrenheit)," Beebe said. "Normally, bean yields start to falter when the temperatures exceed 18 or 19 degrees Celsius (about 64 to 66 degrees Fahrenheit)."

The researchers have bred traits from drought- and heat-resistant but less popular strains, such as the tepary bean cultivated by native Americans in hot and dry environments in the U.S. and Mexico, into more popular varieties such a pinto, white, black and kidney beans.

The tepary bean is a hardy survivor that has been grown since pre-Columbian times, they explain.

Beans are an important and affordable crop vital for the food security of the developing world, providing a highly nutritious food containing protein, complex carbohydrates, fiber, vitamins and other micronutrients.

For their new varieties of beans, the researchers made use of the CGIAR's "genebanks" containing seed collections of the world's most important staple crops, utilizing genomic tools to create the new lines.

"As a result of this breakthrough, beans need not be the casualty of global warming that they seemed destined to be, but rather can offer a climate-friendly option for farmers struggling to cope with rising temperatures," says CGIAR climate change expert Andy Jarvis.

It may be a while before the new "heat-beater" beans can be made widely available, the researchers acknowledge.

"To formally release a variety of crop, it must go through a series of tests, certified by the government, to validate a new variety," says Beebe. "Then it needs to go through a seed production process.

"From now, these processes will take at least two years and in some countries, which have a longer process, it could even take four years," he says.