ABC’s normally excellent Ockham’s razor has taken a refreshing change from presenting the thoughts of scientists on science based on peer-reviewed research to presenting the opinion of a political scientist on global warming based on stuff he found on denialist web sites. Yes, they had Don Aitkin on. Now just because Aitkin isn’t a scientist and his sources weren’t scientists either it doesn’t necessarily follow that he would get his facts wrong, but that would be the way to bet. And if you had bet that way you would have won. Look:
It warmed again from 1975 to 1998, and then it stopped warming again.
It will be plain to you that the IPCC is worried, and in one of its four major reports it went to some trouble to argue that the warming of the late 20th century had no counterpart in the last 1,000 years. … In any case, the paper on which the IPCC’s claim relied was subject to intense scholarly criticism, and was dropped from, and not referred to, in the IPCC’s most recent report.
So I guess the figure below, from page 467 in chapter 6 of the IPCC’s most recent report, must be a hallucination, because it includes the graph from the paper in question, MBH99.
Our present average temperature is not yet at the level of the peak in the mediaeval warm period.
The published scientific evidence rather goes against this claim — see the graph above.
And there is no doubt that the concentration of carbon dioxide in the atmosphere is increasing, at between 1 and 2 parts per million each year. It is at least likely that human activity is responsible for some of that increase.
Jeepers, he’s not giving anything away, is he? If the increase isn’t due to human activities, what is causing it? And where is all the CO2 we emit going?
The correlation between the increase in carbon dioxide and the increase in temperature over the past century, however, is not strong, and over the last ten years is nil.
This isn’t true. Look at the graph from the nice IPCC report:
On the evidence it is not obvious that an increase in the earth’s atmospheric temperature would be a bad thing.
The evidence is in another extensive IPCC report, and an increase is likely to have some bad consequences.
It is worth remembering that the little ice age was a time of food shortages, and it was also the time where in the search for explanation, witches were burned to expiate the evil thought to have caused God’s wrath.
There are echoes of that sentiment today, and because carbon dioxide currently has a bad press, it is worth remembering that all animals depend upon it because it is the chief plant food, and all of us eat plants and/or the animals that eat plants themselves.
The IPCC are basically witch burners and we eat plants and animals. Got it.
For my part, I am as yet unpersuaded that there is good evidence to support the claim that the increase in carbon dioxide concentrations is alarming, and the IPCC has not provided it. What it has done is to model climate, and to provide forecasts of the kinds of climate we might have if various futures were to take place. Some of these forecasts are dire. But models are models; they are not the real thing, and they don’t prove anything.
Yes, for 100% proof, we would have to conduct the experiment. Most of us don’t like to take such risks.