At a meeting in Geneva today, the executive of the World Health Organisation is to consider a report on the impact of climate change on human health.
A WHO report says the populations most vulnerable to climate change will feel the biggest impacts on health.
Residents of small island developing states are among those said to be at greatest risk.
The WHO says there is evidence of a widening in the zones of malaria transmission.
The report says vulnerable areas already have a high burden of climate-sensitive diseases and a lack of health services.
Nations are urged to strengthen public health systems in order to cope with the threat.
