Climate change could cause significant changes to global diets, leading to more than half a million extra deaths in 2050 from illnesses such as stroke, cancer and heart disease, experts said.

As extreme weather such as floods and heat waves wreaks havoc with harvests and crop yields, estimated increases in food availability could be cut by a third by 2050, according to the experts' study published in The Lancet medical journal.

This would lead to a reduction of 99 calories available per person per day, the assessment of the impact of climate change on diet composition and bodyweight found.

Climate change could also lead to a 4 per cent reduction in the consumption of fruit and vegetables, along with a 0.7 per cent drop in the amount of red meat consumed, the study said.

Reduced consumption of fruit and vegetables could cause twice as many deaths as undernutrition by 2050, it said.

"Even modest reductions in the availability of food per person could lead to changes in the energy content and composition of diets, and these changes will have major consequences for health," study lead author Marco Springmann from the University of Oxford said in a statement.

These changes could be responsible for around 529,000 extra deaths in 2050, compared to a future without climate change in which increases in food availability and consumption could have prevented 1.9 million deaths.

Even though some climate-related deaths will be offset by reductions in obesity, the projected 260,000 fewer deaths will be balanced by lower calorie availability, the study said.

Low- and middle-income countries in the Western Pacific region and Southeast Asia are likely to be worst affected, and almost three quarters of all climate-related deaths are expected to occur in China and India.

"There should be enough food to produce a better diet in 2050 than we currently have globally but if you add in climate change then you loose some of those improvements," study co-author Peter Scarborough from the University of Oxford told the Thomson Reuters Foundation.

In Europe, Greece and Italy are likely to be significantly affected, with 124 and 89 deaths per a million people respectively.

Cutting emissions could have substantial health benefits and reduce the number of climate-related deaths by between 29 per cent and 71 per cent, the study said.

"We need to be mitigating greenhouse gasses. If we do, it will bring down the health impact of climate change," Scarborough said. -- Thomson Reuters Foundation