In a paper just published Nature Geoscience titled Test of a decadal climate forecast (doi:10.1038/ngeo1788) forecasts made in a climate models form 1999 have been accurate within a “few hundreds of a degree”.
As the Guardian reports:
The paper, published on Wednesday in the journal Nature Geoscience, explores the performance of a climate forecast based on data up to 1996 by comparing it with the actual temperatures observed since. The results show that scientists accurately predicted the warming experienced in the past decade, relative to the decade to 1996, to within a few hundredths of a degree.
The forecast, published in 1999 by Myles Allen and colleagues at Oxford University, was one of the first to combine complex computer simulations of the climate system with adjustments based on historical observations to produce both a most likely global mean warming and a range of uncertainty. It predicted that the decade ending in December 2012 would be a quarter of degree warmer than the decade ending in August 1996 – and this proved almost precisely correct.
The study is the first of its kind because reviewing a climate forecast meaningfully requires at least 15 years of observations to compare against. Assessments based on shorter periods are prone to being misleading due to natural short-term variability in the climate.
So, scientists created a complex computer simulation in 1999; it has proven to be stunningly accurate.
I can’t wait to see how the denial machine will spin that one.