The prophets of doom point to deaths from heat stress, from violent storms, and from the spread of disease. Heat stress does increase mortality, but it affects typically only the old and infirm, whose lives may be shortened by a few days or perhaps a week. There is no evidence, however, that mortality rates rise significantly. Even during 1988, more than double the number of Americans died from the cold than from the heat of summer. A somewhat warmer climate would clearly reduce more deaths in the winter than it would add in the summer.
Humans also seem to be able to adapt to hot weather.
Adjusting for demographic differences and economic factors, people in cities with hot climates enjoy longer life spans than those in cold areas. A warm climate does not increase mortality. Moreover, the spread of air-conditioning reduces the discomfort from extreme high temperatures. The number of deaths in the United States as a result of hot weather is typically much smaller than the number caused by extremely cold conditions. The President seems particularly keen on the threat from more frequent or violent storms.