The question doesn't hold today. Yes, global warming is (partially) man-made, but that doesn't mean cutting CO2 is the best thing we can do for the future.

If we cut carbon emissions with Kyoto, it will cost $180 billion annually, but only postpone warming for about five years in 2100. We have to ask: Is that what the future really wants?

Take malaria for example. People point out that the spread of the disease will increase with global warming. This is partly true. If we conform to Kyoto Protocols, we will at best cut the total incidences of malaria by 70 million over the century. But if we really
care about the future, we could do so much better. If we spend just $3 billion annually (less than 2% of Kyoto’s cost) on mosquito nets, sprays and medication we could save 28 billion people from malaria. Isn't that better?

Many people would undoubtedly say this only shows we should cut more CO2. But even if stopped global warming right now (very unrealistic) at a cost of much more than $85 trillion, this would only help reduce malaria by one billion cases over the century.

Many would say we should do both. Yes, we should do all good things, but until we do them all, I think we should do the best things first. At the Copenhagen Consensus, some of the world's top economists (including four Nobel Laureates) showed us which solutions do amazing good for our investments (HIV/AIDS prevention does $40 dollars worth of good for each dollar spent, malnutrition $30 for each dollar) whereas Kyoto does only perhaps 25 cents worth of good for a dollar. And cutting CO2 dramatically is even worse (about 2 cents). So the malaria argument, although just one instance, is emblematic of the larger case.

This does not mean we shouldn’t deal with climate change over the long-term, but
we shouldn't make big, expensive, ineffective cuts now (which many politicians promise but inevitably fail to produce). Dealing with global warming is a century long process spanning parties, continents and generations. We need a smart plan. That is not Kyoto. That is investment in R&D for non-carbon emitting energy technologies. I have suggested spending 0.05% of GDP on this -- $25 billion annually. This won't solve global warming overnight, but it will be low-cost and doable. It will solve global warming within a century timescale.

To finally answer the question, let me repeat a story told by Nobel Laureate Thomas Schelling. The UN climate panel expects that the average person in the developing world will be much richer in 2100 than the rich world is today (just like a hundred years ago, Denmark was a poor, peasant state.)

So, imagine an average Chinese, Congolese or Columbian in 2100 thinking back on 2007. Maybe he will be amazed we cared so much about him that we were willing to spend vast sums of money to curb global warming, helping him out just a little bit. But he will likely also think: “How odd that they cared so much for me, who is now rich, but cared so little for my grandfather and my great-grandfather, whom they could have helped so much more, at so much lower a cost. These were the men who needed help most desperately.”