Looks like the same old same old. As soon as someone, even a Professor of Geology comes out with a paper that debunks AGW the alarmsists just go crazy. They cannot bear an opinion that goes against their belief.

Why should a geologist looking at the past not give an opinion? There is so much that has been learned by geologists looking at past climate and changes. These people are looking at far longer periods of time. They should be as well respected as any other academics giving their opinions. They should at least be accorded as much respect as those who work for the IPCC and have computer modelled their findings over the past few hundred years.

Wikipedia as we all know can be changed. People can't surely be going to Wikipedia for actual and accurate information? You don't find the real truth on Wikipedia.

In my previous comment I meant levels of CO2 not seen for 500,000 years, but the point's the same. Also, given that prior natural periods of warming resulted in the release of large amounts of CO2 into the atmosphere, a professor of geology ought to be concerned that we'll see that occur again, making concetrations far stronger and the situation far worse. Warming will also see the release of greater amounts of methane, potentially very large amounts - and it's an even more potent greenhouse gas - on time scales that will strongly impact the world over the lifetimes of people now living.

We dismiss and ignore what the scientists who study climate now know at our peril. Misleading people by using the obvious and uncontested fact that CO2 is, in the right measure, essential and beneficial, to imply that massively increasing it's concentration is not merely harmless, but a positive good is denialist mischief of the worst kind. This article is an appalling abuse of a professor's scientific credentials and position.

Apart from the predictable confirmation-bias produced by this rather silly article, there is some awfully ill-informed opining about carbon dioxide.

Numerous posters have asserted that CO2 is a more or less benign 'trace element' that is required for life; perhaps so, but it appears that their logic is severely impaired, for the next stage in their reasoning is that it must therefore be harmless, perhaps even good for us, no matter the quantity in the atmosphere. They are also nearly 200 years behind what Joseph Fourier already understood in the 1820s about how gases in the atmosphere might trap the heat from the sun. Tyndall's later experiments in the 1850s showed that the amount of 'trace' CO2 could affect the degree of heat radiation in the atmosphere. The Swedes Arrhenius and Hogbom calculated the warming effect of man-made CO2 at the 1896 level of industrial development; their research had begun as an attempt to explain the beginning of the Ice Age.

More about these steps and the work of Angstrom, Callendar, Pless, Revelle and others up to the late 20th century can be read in Spencer Weart's very readable (for the lay person) 'The Discovery of Global Warming' at

http://www.aip.org/history/climate/co2.htm

Statements like 'vilification which has been heaped onto a trace gas which is essential to life', 'carbon dioxide is not a pollutant' and so on are completely meaningless; I'm astounded by how vacuous these statements are. It's a bit like clinging to the belief that the earth is flat or that smoking tobacco is harmless to one's health. Their authors are ignorant of the most fundamental knowledge behind the accumulation of scientific evidence for AGW. They should acquaint themselves with some facts about the ability of the oceans to absorb CO2, and the process of acidification.