If you look at the time period from 1900 to 2050, surprisingly, for a lot of people, the net impact of most global warming was actually positive. That’s because  is actually fertilizer, that means it increases our agricultural production. Of course, in the long run increasing temperatures is also going to reduce agricultural production. We will also see more people die from heat, but many more people will avoid to die from cold, again with moderate global warming. We are also seeing the lower costs of heating outweigh the extra costs of cooling. So, actually, if you look at what the cost is [of global warming] it turns out to be a slight negative around 1900 at about 0.5% and across the most of the century, mostly a negative.