http://arstechnica.com/science/2012/12/ipccs-climate-projections-on-target-so-far/
from the article: A paper in *Nature Climate Change* checks in on the projections from the first IPCC report, published in 1990. That report projected simple trends based on greenhouse gas emissions through 2030, a period were just over halfway through. The most frequently cited projection estimates 0.71.5°C of warming between 1990 and 2030, which means we would see an increase of about 0.35 0.75 °C through 2010. (The range of values is a product of uncertainty about the exact sensitivity of climate to greenhouse gases.) The observed temperature trend through 2010 is about 0.350.39°C, depending on the dataset. So, is it as simple as saying the projection was (barely) correct, but overestimated warming? Not really. The first thing to do is account for natural variability. The researchers chose to address this by running many climate model simulations in a stable configuration with no drivers of warming or cooling. Ninety percent of the natural variability fell within a range of ±0.19°C. If you apply that as a measure of potential noise around the signal of the underlying trend, the projected warming by 2010 becomes 0.28 0.81°C, which includes the observed trend a little more cleanly. Its also important to note that both the projection and the observed trend lie above the estimated range of natural variability. That means the difference between the observed warming and natural variability is statistically significant. -- Larry C. Lyons web: http://www.lyonsmorris.com/lyons LinkedIn: http://www.linkedin.com/in ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Order the Adobe Coldfusion Anthology now! http://www.amazon.com/Adobe-Coldfusion-Anthology/dp/1430272155/?tag=houseoffusion Archive: http://www.houseoffusion.com/groups/cf-community/message.cfm/messageid:360331 Subscription: http://www.houseoffusion.com/groups/cf-community/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/groups/cf-community/unsubscribe.cfm
