Global warming will fail to reduce high winter death rates as some officials have predicted because there will be more harmful weather extremes even as it gets less cold, a British study showed on Sunday.

A draft U.N. report due for publication next month says that, overall, climate change will harm human health, but adds:

Recent storms caused major disruptions across Japan.

"Positive effects will include modest improvements in cold-related mortality and morbidity in some areas due to fewer cold extremes, shifts in food production and reduced capacity of disease-carrying vectors."

However a report in the journal Nature Climate Change on the situation in England and Wales said climate warming would likely not decrease winter mortality in those places. It suggested more volatile winters, with swings from cold to mild linked to rising greenhouse gas emissions, might even raise death rates.