Would global warming be a bad thing? (updated)

Mortality in Britain is lowest when the mean daily temperature is 17-18°C. The number of heat related deaths per year, obtained as the number of excess deaths on days hotter than this, has averaged around 800 in recent years. Most of those deaths are of people over 70 years of age, and most occur in the first day or two of a period of high temperature...

According to some predictions heat related mortality will increase drastically as global warming develops, but recent evidence is relatively reassuring. Heat related mortality is similar in hot and cold parts of western Europe and in hot and cold parts of the United States. This implies that the populations of hot regions have adjusted by physiological or other means to their hotter summers. In Britain annual heat related deaths are in any case far fewer than cold related deaths, so that the initial effect of increased temperatures all year round, [even] before such adjustment, would be to reduce net annual mortality.

Update: Jerome Schmitt notes that the Financial Times also points to uneven benefits and penalties from global warming:

Fewer in the north would die of cold, crops there would boom and the North Sea coast could become the new Riviera, an analysis to be approved by the European Commission next week shows. But the annual migration of rich northern Europeans to the south could stop – with dramatic consequences for the economies of Spain, Greece and Italy. [....]

While fewer people will perish of cold in the north, tens of thousands more will die of heat in the south. As many as 87,000 extra deaths a year would occur annually by 2071, assuming a three degree centigrade temperature rise. If efforts to curb greenhouse gas emissions limit the rise to 2.2 degrees, additional mortalities would be 36,000 a year
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These numbers are dwarfed by predicted deaths and economic chaos in the developing world.