im basically retyping the points made in http://www.youtube.com/watch?v=zORv8wwiadQ&NR=1&feature=fvwp
as it seems sceptics have completely missed this simple and elegant point.
look, if you do nothing about global warming then there are 2 options:
1a. global warming was not caused by manmade gases and we did nothing, so all is good, we spent no money on useless clean tech and we keep polluting happily until other problems arise due to this continued shortsightedness.
2a. global warming was indeed facilitated by manmade gases and we did nothing to avoid the results. In this case the future will be some ways between the high-end and low-end predictions for the next 50-100 years. At the critical end of the scale there will be half a billion people forced to seek new place to live due to rising water levels/changed rainfall patterns/ increased tornados and tsunamis. This in turn will create much more economic/social/political pressure due to aid/food/water/living space > more wars. This option possibly includes the economic depression of the 1st option, but has so much more bad results.
Now, if we DO SOMETHING to stop global warming then again, there are 2 options:
1b. again, if global warming was not caused by manmade gases and hence the money we spent trying to stop it was not effective, another economic depressions is possible, but i would say unlikely, as the investments in clean technology and new energy would create much sustainable growth.
2b. if global warming was caused by man, and we did DO SOMETHING to stop it and it worked, then its money well spent. Sure it would be a huge cost to bear and huge changes in the world economy, but in the end, we avoided the global catastrophe in option 2a.
stopping climate change:
action taken YES NO
ok consider this little table.
we can influence the future. we cant know for certain, wether global warming is manmade or not, but we can decide the column that our future will fall into. Its either the YES or NO column for taking action against global climate change. Now if we choose the NO option, then by that, we allow the future where there is a possibility of a global catastrophe. By choosing YES column, at worst we choose the option where we will spend a lot of money on going greener and cleaner but it wasnt that necessary to begin with. Now i would rather be safe than sorry and like i mentioned before in this wall of text, i think it might have a positive effect for the economy and the planet in the longrun to invest in clean tech.