1936

Background: It is known that on days with high temperatures higher mortality is observed and there is a minimum mortality temperature (MMT) point which is higher in places with warmer climate. This indicates some population adaptation to local climate but information on how quickly this adaptation will occur under climate change is lacking.
Methods: To investigate this, we associated daily mortality data with temperature during the warm period in 2004-2013 for deaths among London inhabitants born in five climatic zones (UK, Tropical, Sub-tropical, Boreal and Mixed). We fitted Poisson regression with distributed-lag non-linear models for each climatic zone group separately to estimate group-specific exposure-response associations and MMTs. We report relative risks of death comparing the 95^th percentile (21 ^oC) and maximum (25 ^oC) of the temperature distribution in London with the zone-specific minimum mortality temperature.
Results: No heat-related mortality was observed for people born in countries with Sub-tropical and Mixed climates. We observed an increase of 26%, 35% and 39% in the risk of death at 25 ^oC compared to the MMT in people born in the UK, Tropical and Boreal climate respectively. The minimum mortality temperatures in these groups ranged from 15.9 to 17.7 ^oC.
Discussion: Our findings imply that people born in different climatic zones do not adapt fully to their new environment within their lifetime. This implies that populations may not adapt readily to climate change and will suffer increased effects from heat. In the presence of climate change, policy makers should be aware of delayed process of adaptation.