On September 27, the Intergovernmental Panel on Climate Change (IPCC) will release part of their fifth assessment report on climate change. For the first time since 1990, this report will scale back the hysteria on global warming.
Matt Ridley at The Wall Street Journal viewed a few leaks from the 31-page document and talked to one of the senior climate scientists. The temperature rise due to man-made carbon dioxide is lower than their prediction in 2007. Originally a three degrees Celsius increase was predicted, but that number is now expected to be between 1-2.5 degrees Celsius.
Specifically, the draft report says that “equilibrium climate sensitivity” (ECS)–eventual warming induced by a doubling of carbon dioxide in the atmosphere, which takes hundreds of years to occur–is “extremely likely” to be above 1 degree Celsius (1.8 degrees Fahrenheit), “likely” to be above 1.5 degrees Celsius (2.4 degrees Fahrenheit) and “very likely” to be below 6 degrees Celsius (10.8 Fahrenheit). In 2007, the IPPC said it was “likely” to be above 2 degrees Celsius and “very likely” to be above 1.5 degrees, with no upper limit. Since “extremely” and “very” have specific and different statistical meanings here, comparison is difficult.
Most experts believe that warming of less than 2 degrees Celsius from preindustrial levels will result in no net economic and ecological damage. Therefore, the new report is effectively saying (based on the middle of the range of the IPCC’s emissions scenarios) that there is a better than 50-50 chance that by 2083, the benefits of climate change will still outweigh the harm.
Warming of up to 1.2 degrees Celsius over the next 70 years (0.8 degrees have already occurred), most of which is predicted to happen in cold areas in winter and at night, would extend the range of farming further north, improve crop yields, slightly increase rainfall (especially in arid areas), enhance forest growth and cut winter deaths (which far exceed summer deaths in most places). Increased carbon dioxide levels also have caused and will continue to cause an increase in the growth rates of crops and the greening of the Earth–because plants grow faster and need less water when carbon dioxide concentrations are higher.
Ridley pointed out that many papers in the last year have come to this same conclusion. Scientists at the University of Illinois and Oslo University in Norway found the ECS levels would be lower than the models showed. Three papers followed, including one produced by 14 lead authors of the IPCC report, that backed the evidence. Francis Zwiers and others at the university of Victoria, British Columbia found that global warming was overestimated by 100% over 20 years.
No word yet on Al Gore’s reaction to this very important report.