1) It’s probably true that human activity has had a warming effect on the global climate.
2) It’s probably NOT true that it will result in a complete global disaster that will cause the extinction of human beings. For one thing, it is has been shown that the climate has varied wildly over the history of the planet. For most of earth’s past it has been much warmer than it has been in its recent history. However a significant change could cause a great deal of disruption and possible suffering for humanity. But balanced against that, massive government intervention in the economies of the world could possibly cause even more disruption and suffering – especially given that we probably have less understanding of the intricacies of economics than we have of climate science.
3) However, if there is a possibility that a global catastrophe could occur, we should weigh the risks using rational cost/benefit analysis, and NOT using the “Precautionary Principle”. The “Precautionary Principle” is an insane “solution” that only takes into account the worst possible scenario – it’s akin to the “Zero Tolerance” policies that have been promulgated in the public schools; e.g. - children being suspended because they brought forks or aspirins to school. If scientists believe the Precautionary Principle should be used as guidance for solving global warming, then they should also use extreme measures like shutting down the Large Hadron Collider, on the off chance it might make a black hole that will swallow the earth. You can’t have it both ways.
4) Finally, does anyone really believe that the Machiavellian politics of the UN and world governments will be able to “solve” anything?! Here’s just one of countless examples: Do you think Comrade Putin will generously go along with measures to massively reduce greenhouse gases? Just look at the thousands of miles of frozen coastline in northern Russia, and the millions of square miles of frozen land in Siberia. Do you think Comrade Putin will make such huge sacrifices as stopping the drilling and use of fossil fuels to help the poor people of Bangladesh? It might be a nice legacy for Mr. Putin to be remembered as the one that opened up so many new resources for Russia. Who would have thought the “Climategate” scandal would have been caused by Russian “patriots” in Siberia.