Scientists say planet is warming at half the forecast rate

Business

LAI SEE

Howard Winn

We see that recent leaks of the UN Intergovernmental Panel on Climate Change (IPCC) report due to be published later this month show that the planet has been heating up at half the rate claimed by scientists in the 2007 IPCC report.

In that report, scientists said the planet had been warming at 0.2 degrees Celsius every decade. But the new report states the rate has only been 0.12 degrees since 1951.

This is a marked departure from the apocalyptic scenarios that were forecast in earlier reports. It also has implications for policymakers that have spent billions in trying to mitigate this perceived problem.

In another striking departure, the report acknowledges that large areas of the planet were as warm between the period 950 and 1250 as they are now, despite the much lower levels of man-made carbon dioxide.

One of the central arguments of previous IPCC reports has been that man’s production of carbon dioxide has contributed to half of the planet’s global warming, with the rest coming from natural occurrences such as the change in sun spot activity and ocean warming cycles.

Another difficulty has been that while a quarter of the volume produced by human activity since 1750 had occurred in the past 10 years, the planet’s temperature has not risen in the past 17 years. Indeed, the new report says “models do not generally reproduce the observed reduction in the surface warming trend over the last 10 to 15 years”.

The IPCC has also scaled down its estimate for the rise in sea level by the end of the century from the somewhat scary one to two metres to 40 to 62 centimetres. The worry is that if climate models exaggerate global warming for past decades, what sort of guide are they for the future.

A recent Nature Climate Change study shows the main climate models have overestimated the rise in temperature of the past 15 years by more than 300 per cent.

Despite all this, the IPCC report will claim that scientists are now 95 per cent certain that humans caused more than half of the global rise in temperature since 1950, an increase from 90 per cent in the 2007 report.