Farmers in cropping areas that rely purely on rain are going to struggle as the Earth gets hotter.
A study released in Nature has found prolonged global warming would cause dryland areas to become drier, which would change soil nutrients and slash plant yields.
The research was carried out at 224 dryland sites in 16 countries across the globe.
One of the sites was north of Mildura, in south-west New South Wales.
University of New South Wales associate professor David Eldridge says declines in average annual rainfall will have huge consequences for farmers.
"With an increase in aridity, in other words a reduction in our average annual rainfall that's predicted over the next 100 years, what that's going to do is create an imbalance in carbon, nitrogen and phosphorous cycles, which has major impacts on productivity and diversity in these semi-arid systems," he said.
The study assessed soil that had an average rainfall between 100 and 800mm a year.
Dr Eldridge says drylands cover 41 per of the globe and support about 40 per cent of the world's population.
He says people will become more reliant on crops from drylands as the global population increases.
"It's the marginal cropping areas that are going to be mostly affected," Dr Eldridge said.
"It's going to be people living in less developed areas that are going to be most affected.
"It's going to potentially have major impacts for plant production and for the way we manage these semi-arid systems."
© ABC 2013
11:13 EST The New South Wales State Emergency Service (SES) says it has received about 1,000 calls for help since a severe hail storm hit Sydney and the Blue Mountains late yesterday, adding to the backlog created by a powerful east coast low earlier in the week.