"For we are not dealing with testable scientific propositions: we are dealing with a bunch of forecasts..."

Every day, in every Australian state, the Bureau of Meteorology produces a set of testable scientific propositions that is broadcast on the nightly TV news broadcasts - it's called the weather forecast. The test is simple - does the weather that actually happens the next day match the forecast.

The IPCC forecasts are subject to a similar test - hang around for 100 years (if you can) and see what the climate is like. If that's a bit too strenuous for you, then the next best thing is to look to the shorter term predictions and see how they turn out.

Either way, Lawson's assertion that the IPCC forecasts are not testable scientific propositions is wrong.

"There is no doubt that temperatures have increased by about a degree or so since 1860"

I used to agree with this assertion. I mean how hard can it be to reliably collect temperatures over the years, via a simple, consistent scientific system of data collection?

It seems it is harder than I thought....
http://www.surfacestations.org/

So the temperature data has a lot of corruption in it...add that to the large error bars in most of the variables and really, the climate change alarmists are really just blowing hot air....

"Waving a bunch of computers at a set of bad assumptions will not turn them into good forecasts, but the result can be bad policy."

That sums up the climate debate and the real dangers of developing a carbon trading regime based on forecasts of it.

"Tweaking" or "massaging values" might not matter when the implications are limited or local but it makes a whole lot of difference when they are applied globally.

Case in point, an Australian economic model, might have several thousand independent variables within it, that might work roughly to suit predictions of tax collections etc (although the actuals v budget in the past 7 years since GST was introduced would suggest some more "Tweaking" is required).

So several thousand variables being used to "model" a society of 20 + million real "independent" variables and the ATO still get it wrong.

Now extrapolate (another device frought with error) that to a world population of 6 1/2 billions + and I figure you need an enormous model with millions of independent variables.

The scientific gallahs are talking about the impact of an increase of 1 degree in water temperature as having catastrophic effects.

A 1 degree change might represent a 3% average increase from the starting point, that is probably 1/10th the error factor inherent in their model.

When the measured impact of a forecast outcome is less than the error factor, developing policy based on that outcome is more than likely to bring about more erratic and unexpected results (and usually more detrimental ones), compared to doing nothing.

I am with the skeptics on climate change modelling (and rapidly moving toward the cynics), not because I think that modelling is wrong (I have done heaps of economic modelling over the past 30 years) but because basing social/economic policy on unprovable assumptions is wrong, stupid and downright dangerous.

Mark Lawson....you are an ignorant man or one who is captured by the industries who refuse to mitigate their pollutant emissions or their bank balances.

Why don't you lobby to change the IPCC title to the IPAP? That stands for the International Panel for Anthropogenic Pollution. Would you continue to raise your illogical arguments over the science of man-made pollution? Will you respond to that question? No I didn't think you would.

Climate change and pollution have a common cause and a common resolution. Cease polluting!

153 nations at the Rio Summit in 1992, signed treaties to reduce GW, save endangered species and foster sustainable development. It hasn't happened - thanks to the likes of you and your cronies.

We've continued to despoil the earth by increasing pesticides, hazardous waste, more chemicals contaminating the entire food chain and significantly affecting health and the economy but increasing profits for a few at the big end of town.

Add the toxicity of military and industrial air pollution and agricultural chemicals to soil erosion, floods, fires, population explosions and social unrest and you have the formula for an unstable ecosystem that will become even more uninhabitable.

Millions of people around the globe die from air pollution and you continue to bang your gums about the lack of consensus on climate change.

The "Polluter Pays" principle or the "Precautionary Principle" won't happen in this neck of the woods so you may continue to inhale your toxins, Mr Lawson.

Many of us are well aware that politicians are short-termed administrators - inexperienced, poorly informed and ignorant.

I suggest you and other sceptics access any basic manual on environmental toxicology, in an endeavour to restore any credibility you may have had prior to your senseless bleatings on OLO.

Dickie, You seem to be going seriously off topic. The assertion is that carbon dioxide is causing global warming. CO2 isn't killing anyone or causing disease, your thinking of other chemicals which are pumped into the atmosphere. Breathing CO2 isn't harmful in itself. CO2 is a vital part of our ecosystem, plants use it to breathe. So just slow down a bit. The only way CO2 is harmful is IF it causes global warming and IF that global warming results in serious harm to our ecosystem.

What "proof" (or degree of certainty) of AGW and its impacts would people like before they would be willing to act in a more environmentally sustainable way? Seriously.

Anyone?