Apparently, an economist has estimated the environmental cost of global warming (assuming the globe does warm) at $23 trillion in 2005 dollars through 2100. I haven't read the book and can't vouch for his methodology, but it's hard to believe that all this hype has been built up over something so trivial.
This years global "GDP" is estimated to be approximately $77 trillion, so the damage from global warming over the course of the 21st century isn't even a third of one years GDP. If we assume a very conservative 1% average real growth in the world economy this century, world GDP in today's dollars in 2100 will be just shy of $200 trillion and total GDP over the next 92 years will be $11.7 quadrillion. So, what in the world is all the fuss about?