Chris Field, Coordinating Chair of the Climate Impacts Working Group for the IPCC says:
"We now have data showing that from 2000 to 2007, greenhouse gas emissions increased far more rapidly than we expected… In the fourth assessment, we looked at a very conservative range of climate outcomes, the fifth assessment should include futures with a lot more warming."
"We are basically looking now at a future climate that is beyond anything that we’ve considered seriously in climate policy…" Greenhouse gas emissions have grown by an average of 3.5 per cent a year from 2000 to 2007. Fields said this was "far more rapid than we expected" and more than three times the 0.9 per cent growth rate in the 1990.
The IPCC average warming from the 2007 report was about 6 to 7 degrees F. over the next century. One of the few irreversible feedbacks that we have been able to determine so far is that Greenland will cross the meltdown threshold at 2 to 3 degrees of warming – well within the built in warming already in the pipeline. Modeling efforts at NASA Goddard Institute for Space Studies led by James Hansen show that there is a real risk of the Venus Syndrome occurring on Earth if we see 15 to 30 degrees of warming. Fields’ warning of "a lot more warming" comes dangerously close to this ultimate Venus Syndrome scenario outlined by Hansen (see December 22, 2008 entry below).
The range of warming in all IPCC 2007 scenarios was 2 to 11.5 degrees F. What is happening with all of these reports that the IPCC 4th Assessment is conservative is obvious. We have crossed the threshold, climate is changing much faster than expected. The reason that the scientist can not say this with certainty is that science generally works on known events, not circumstantial evidence. The IPCC stopped taking papers in 2005. The papers published in 2005 collected their data, typically, no later than about 2003, much was collected no later than 2000 or 2001.
Science doesn’t happen overnight, but climate change does. Ice records show average worldwide temperature changes of 9 to 10 degrees F. occurring in as little as a year or two. These changes, or similar abrupt changes, have happened 25 to 30 times in the last 100,000 years, and in the nine previous 100,000 year periods, similar abrupt changes took place.
The big problem is, that we have never seen, on a planet that is similar to ours tectonically, an abrupt change that started at the average temperature that our planet is experiencing today. Today’s temperature is within just one or two degrees of being as warm as it has been in likely the last three million years – that period, tectonically, where we can compare different CO2 concentrations.
Of the 750 to 1,000 or so abrupt climate changes that have occurred in the last 3 million years, none have started with temperatures as warm as they are today, with prospects of becoming as warm as they possibly could.