The issue of climate change is very confused because there are two aspects which are continually mixed up and really should be separated.
One aspect is the fact that climate is always changing due to natural causes; always has been and probably always will. The other aspect is the role played by increased CO2 levels (and other man-made greenhouse gasses) in this unavoidable, natural process of climate change.
Those who are forecasting disaster would claim that increased CO2 levels from man-made emissions, in a climate which may already be in a warming phase through natural causes, will exacerbate the trend and get us to a disastrous tipping point which we would never otherwise have reached.
On the other hand, if the climate is in a cooling phase, then anthropogenic contibutions to greenhouse gasses, by the same reasoning, would tend to reduce the impact of such cooling, and be a good thing.
It seems to me that the science of climate is so complex and contains so many chaotic elements, it's impossible to separate these two influences on climate, ie. natural cause and anthropogenic causes. The science is therefore uncertain and cannot be otherwise.
Uncertainty, however, does not lend itself to political action.
Professor Stephen Schneider of Stanford University (Professor of Climatology and author of many IPCC reports) has explained the process very well in my view. Here's what he said some time ago.
On the one hand, as scientists we are ethically bound to the scientific method, in effect promising to tell the truth, the whole truth, and nothing but – which means that we must include all doubts, the caveats, the ifs, ands and buts. On the other hand, we are not just scientists but human beings as well. And like most people we’d like to see the world a better place, which in this context translates into our working to reduce the risk of potentially disastrous climate change.
To do that we need to get some broad based support, to capture the public’s imagination. That, of course, means getting loads of media coverage. So we have to offer up scary scenarios, make simplified, dramatic statements, and make little mention of any doubts we might have. This “double ethical bind” we frequently find ourselves in cannot be solved by any formula. Each of us has to decide what the right balance is between being effective and being honest. I hope that means being both.
This process of deception appears now to be unravelling. As that great author, Sir Walter Scott, wrote many years ago, "Oh! What a tangled web we weave, when first we practice to deceive."