An Oxfam report says climate-related disasters killed 21,000 people in the first nine months of this year, more than double the number in 2009.
Timed to coincide with the start of international talks tackling climate change in Mexico, the report cites sea level rise in Tuvalu as an example of the deadly consequences of climate change.
The new round of UN climate negotiations aims to agree on a narrow range of issues dividing rich and poor economies, specifically on funding, preservation of rainforests and preparations for a warmer world.
The report says sea-level rise and soil salinisation in the Pacific continues to harm coastal agriculture.
It says people in Tuvalu are now finding locally-produced fresh food increasingly limited, and locals are now relying more on imported processed foods to survive.
It says medical problems like diabetes and hypertension - previously little known in the country - are now on the rise.