LONDON, (Reuters) – The world needs genetically  modified crops both to increase food yields and minimise the  environmental impact of farming, Britain’s top science academy  said yesterday.  

The Royal Society said in a report the world faced a “grand  challenge” to feed another 2.3 billion people by 2050 and at the  same time limit the environmental impact of the farm sector.  

The world will have to increase food output by 70 percent  and invest $83 billion annually in developing countries by  mid-century, the U.N.’s Food and Agricultural Organisation said  earlier this month.  

“The problem is such an acute one, doing that sustainably  without eroding soil, overusing fertilisers is an enormous  challenge,” said the chair of the Royal Society report,  Cambridge University’s David Baulcombe.  

“There isn’t a lot more land to use,” he told Reuters. “And  from the point of expense and using fossil fuels, we want to use  less fertiliser.”  

“The food supply problem is likely to come to a head 10, 20,  30 years from now,” he said, adding this didn’t leave much time  given the research lead time to develop new crops.  

The answer would be a range of approaches from hi-tech  genetically modified crops to low-tech management approaches  such as sowing grass around maize to divert pests, as well as  preserving the diversity of natural, wild crop varieties.