Climate claim disputed

Letter,

Business Age

November 22^nd 2007

In response to the latest IPCC report, former CSIRO climate expert, Barrie Pittock, claims that greenhouse gas emissions, global warming and sea level are all running at the very top of the range of uncertainty in IPCC estimates and that this indicates the need for action to reduce emissions within the next year or two as well as large investments in renewable energy ("Warming puts heat on political leaders", 20 November).

But he fails to acknowledge that this so-called Synthesis report of the IPCC (which is supposed to the last word on warming and what to do about it) does nothing to respond to the growing criticism of the underlying analyses of the causes of global warming, including the analyses used in deriving that organisation's temperature estimates from computer models.

For example, it is widely accepted that the warming effects from greenhouse gas emissions diminish progressively as atmospheric concentration levels of carbon dioxide increase.

This has been acknowledged in all IPCC reports but its importance is overlooked, a development that adds to doubts about other IPCC objectivity . If carbon dioxide levels have in fact reached the point where they are ceasing to have any significant warming effect, as many scientist suspect, the IPCC argument for urgent action to reduce emissions of carbon dioxide would cease to have validity.

Recent published research also shows that the increase in evaporation as temperature rises, which is an important natural constraint on such increases, is on average underestimated in the computer models used by IPCC by a factor of three. This raises a further doubt about IPCC temperature estimates.

Pittock also points out that there has been much melting of Arctic sea ice.

But he fails to mention either that this has happened in the past when it could not have been caused by carbon dioxide-induced emissions or that researchers from NASA have shown it probably mainly reflects the effect of an apparently not infrequent reversal in the circulation of the Arctic ocean.

At least Mr Pittock did not quote the UN Secretary General, Ban Ki-moon, who gave the IPCC report wide publicity on TV by visiting the Antarctic and claimed to have personally observed global warming. The only problem for Ban is that satellite and other data show a decrease in temperatures in Antarctica and surrounding seas of the southern ocean over recent years.

The action of Ban is just one example of attempts originating from various sources to sound alarm bells when the evidence of fires is simply not sufficient to warrant action.