A leading climate change scientist says tropical islands in the Pacific are going to regularly experience heatwaves of unprecedented magnitude over the next century.
Auckland University's Dr Jim Salinger says Pacific countries are going to need more help from their neighbours to deal with the affects of climate change.
He says people need to start changing the way they live.
"We've really got to recarbon our societies by 2050, go to other fuel sources," he told .
"We've got to look to moving to species for example that can take the drier periods... not putting huge amounts of stock on the land."
Dr Salinger is also predicting severe droughts will occur more frequently in New Zealand and the Pacific.
He says droughts that happened once in 20 years in New Zealand will be every two to five years by 2100.
"The climate is warmer so agriculturally there is more evapotranspiration," he said.
"It's hotter so things dry out earlier, and the anticyclonic belts are getting stronger, that's the belts of high pressure."
He says global food supply will also be challenged, with falling crop yields in countries like Australia, India and Africa.