Lets look at the IPCC 4th assement models against reality Figure 2: Solid lines are multi-model global averages of surface warming (relative to 1980–1999) for the scenarios A2, A1B, and B1, shown as continuations of the 20th century simulations. Shading denotes the ±1 standard deviation range of individual model annual averages. The orange line is for the experiment where concentrations were held constant at year 2000 values. The grey bars at right indicate the best estimate (solid line within each bar) and the likely range assessed for the six SRES marker scenarios. A2 is slightly lower in rate during the next 20 years. Most likely caused by sulfurs, but ends the highest at 2100 as the level of co2 increases as the sulfur, aerosals decrease. This is on a 1980-1999 baseline, so we have to match the giss record to that.... ------What occurred, A2, A1b1 2002 .33c, .262c, .272c 2005 .37c .349c .339c 2007 .37c .373c .401c 2010 .40c, .423c, .408c Model data http://www.ipcc-data.org/data/ar4_multimodel_globalmean_tas.txt 2010 giss Data.GISS: GISS Surface Temperature Analysis 2005 Data.GISS: GISS Surface Temperature Analysis 2007 Data.GISS: GISS Surface Temperature Analysis Here are some predictions from the ipcc models Year, A1b1, A2 2012 0.516 0.461 2015 0.546 0.526 2018 0.605 0.553 2020 0.684 0.615 2030 0.944 0.809 I'd likely go with A2...Why, because it is handling the aerosals much better as are emissions put out sulfur at the rate we're increasing them. I'd also wouldn't judge these models from anomaly's like 1998, 2008, 2011. ---A2 is lower throughout mid century even with higher emissions for this reason. I expect it is right. Aerosals for the next 20-30 years will hold it down. Longer term 2060 onwards A2 with higher emissions over takes A1b1. http://www.ipcc.ch/graphics/2001wg1/large/01.33.jpg Here is the emissions. We're close to A2.