The issue with stopping or reducing global warming is about risk and managing risk: Science still does not know the exact mechanism by which smoking and its associated chemicals causes cancer. What we do know is that smoking is the biggest risk factor in developing lung cancer. The more you smoke, the more your risk of getting lung cancer. Not everyone who smokes gets lung cancer, and not everyone who gets lung cancer has smoked.
Similarly with Climate Change (global warming), we are seeing that temperatures are rising at the same time that atmospheric greenhouse gas levels have gone off the charts over the last 650,000 years.
If the IPCC is right, and we don't do anything, we risk massive temperature increases that will lead to the loss of the great ice sheets of Greenland and Antarctica, resulting in a 20 foot increase in sea levels.That would take about 100 years if we do nothing. Almost all of the major population centers located on coasts (check out the % of Asia, Europe, and North American cities which would be affected.) Global warming causes huge costs if that is right.
If the IPCC is wrong, and we do everything we can to reduce new emissions of greenhouse gases, we would reduce the annual increase of global GDP by 0.12%. Since global GDP is growing around 3%, that is not a big cost.
This is exactly why people buy insurance. Most Americans will never have a fire. Only about 1% will ever have a house fire. However, most Americans buy fire insurance. Why? Managing risks. Science has told us the facts about global waming. It's up to us to manage the risks involved with global warming.
(from an anonymous comment on our website)