Forget mirrors in space and seeding the oceans with iron, scientists have come up with a new way to tackle the looming threat of global warming: fields of shiny crops.

Experts at the University of California, Irvine, say reflective plants could send more of the sun's heat back into space, and even reverse temperature rises in parts of the world. Encouraging farmers to grow shinier crops could reduce maximum daytime temperatures in agricultural regions by as much as 1.9C, they say.

The scientists are unwilling to discuss their idea until it is published in an academic journal later this year, but they revealed the details last month at a special geoengineering session of the American Geophysical Union meeting in San Francisco.

Some climate experts say that such emergency geoengineering measures, including artificial volcanoes and orbiting sunshades, could be needed in future to tackle rising temperatures, if world leaders fail to constrain soaring greenhouse gas emissions.

Increasing the amount of sunlight reflected back from land, called its albedo, could offset the damaging effects of the loss of Arctic ice, where the shiny white polar cap is being steadily replaced by darker water, which absorbs more heat.

The California team, led by Chris Doughty in the department of earth system science, told the conference: "Slowing or reversal of regional warming trends may be achieved by manipulation of land surface albedo. This approach is most feasible in agricultural and forestry areas, where the land surface is already under significant human influence."

Plant breeders have already created an extra-hairy variety of soya bean to fight pests, which reflects about 5% more sunlight than normal, they said. Soya alone is planted across 1m sq km, an area four times the size of the UK, mainly in Brazil, Argentina and the United States. The agricultural cooling scheme would probably not work in countries close to the equator, where the extra heat reflected could shrink cloud cover, and allow more sunlight through.

Other scientists have suggested different ways to cool the planet by making it more reflective, including growing broadleaf varieties of trees instead of conifers, and painting roads, roofs and car parks white.