The vast majority of climate scientists and those in related fields agree that the Earth is warming and that it is human activity that is responsible for this change.The evidence for man made climate change is overwhelming and has been repeatedly confirmed, the evidence against man made climate change is sparse and unable to withstand critical scrutiny. So I'm going to go with the vast majority of people who know about this kind of thing and who have the evidence on their side and say that global warming (more accurately climate change) is happening.
The recent IPCC report confirmed it for me, have a look at the summary
http://en.wikipedia.org/wiki/IPCC_Fo...essment_Report
As for the economic impact of combatting climate change, yes it will cost money, but in the longer term it will save much more. According to the Stern report, a purely economic look at the impact of climate change commisioned by the UK government, combatting climate change could cost 1% of global GDP (gross domestic product) each year. Which is a lot of money, but the estimated costs would be equivalent to losing at least 5% of global GDP each year, now and forever. And if you go for the worst case scenario considered in this report then that figure rises to 20%.
For the Stern report conclusions see -
http://www.hm-treasury.gov.uk/media/...onclusions.pdf
Plus millions of people will die and millions more be forced from their homes. So if you think immigration is bad now just wait till heavily populated areas like Bangladesh become unable to support their population.
I understand the arguement about "why should we bother if China and others don't", but look at it another way, why is China going to bother if the US doesn't? It's great for them, the US gets all the abuse and pressure for not doing much about emmisions and they get none. If China was the only country not to be doing anything then the reast of the World could put some pressure on them. Unless the US starts doing something about climate change then there is no reason for anyone else to.
As far as I'm concerned climate change is happening, it is going to get worse and we should do our best to stop it happening for moral and financial reasons. But it looks like short term financial excuses and national interests are going to prevent us from doing anything.
I guess we are going to find out if it's a myth or truth. I hope it's a myth, I really do.