Climate change skeptic turned proponent

[Aractus]

On a point of order, to embed the video just put the youtube url with no syntax in the post. I can't see it embded in either FF or Chrome. Also, use http and NOT https like so:

http://www.youtube.com/watch?v=kTk8Dhr15Kw

or

http://youtu.be/kTk8Dhr15Kw

http://www.youtube.com/watch?v=kTk8Dhr15Kw

The famous Richard Muller professor from UC Berkeley who doubted the climate change was real back in 2003. He formed his own group to study the issue and came to the same conclusions as previous climate scientist. His "conversion" story just under 5 minutes.

(video)

Best line is at the very end, "If you say it's something else and I don't know what it is, my answer is something else that just happens, by accident that perfectly matches the carbon dioxide increase ... are you serious?"

He did not in my view put forward a convincing argument at all. All his arguments amounts to is that "I found correlation between CO2 and climate change". So what? Sceptics acknowledge that, and sceptics also acknowledge that CO2 should have some effect on raising global temperatures. The models put forward by NASA and others have CO2 contributing at most 50% of the global warming trend since the beginning of the 20th century, with black carbon and methane mostly making up the rest. There's no computer model on the planet that proposes that CO2 is solely to blame.

But really even that is not what climate scepticism is about. Climate scepticism is not about the past and whether nor not CO2 is 50% responsible for the 20th century trend of global warming, but let's assume for argument's sake that it is and that the science is totally 100% settled on that.

If you look at the infrared spectrum which CO2 absorbs you see that the present quantity of CO2 in the atmosphere absorbs nearly the total of what it appears to be capable of absorbing. Let's say that CO2 global mean concentration today is roughly 400ppm, and that we really started this trend back at around 285ppm.

H2O was thought to be responsible for between 90-95% of the greenhouse effect on our planet. That's a large margin for error since it then means the remaining minor gasses are either between 5% to 10% responsible in total. The total greenhouse effect is also not known, it is however estimated.

In recent years those numbers have been revised, it is now believed that H2O is between 36-70% responsible, and CO2 between 9-26%! That's now a much larger margin for error than what was thought ten yeas ago!!

Now to get back to the point. Climate sceptics don't deny that CO2 effects the global temperature - of course it does since it's a GHG. They also don't deny that it contributes to global warming - it should contribute something because it's risen from 285ppm to close to 400ppm.

The things that climate sceptics doubt are these: 1. that greenhouse gasses are the major or primary driver of present climate change; 2. that there's a negative feedback mechanism that makes temperatures "spiral out of control".

There are a further two observations made by the sceptics: 1. that all predictions over the past 20 years have been dramatically wrong and that even the IPCC's predictions for the next 100 years have been progressively scaled down; 2. that while it's true that no one has an alternative explanation for the exact cause of the 20th century warming trend, it's also the case that no one has been able to fully explain prior climate change and what its causes were and in particular the MWP. If we can't explain what caused climate change 1,000 years ago, then what makes us so sure we can explain what is causing climate change today?