On 1 May 2007, the online edition of Geophysical Research Letters will publish a study by a combined team from the National Center for Atmospheric Research (NCAR) and the University of Colorado’s National Snow and Ice Data Center (NSIDC). This study report will show, in yet another way, how the Intergovernment Panel on Climate Change (IPCC) report is overly optimistic and is likely understating the risks and impact of Global Warming. In this case, the to-be-published study: ‘
Arctic Sea Ice Decline: Faster Than Forecast?
This study examined the 18 different computer models used by the IPCC and compared the models’ predictions about Artic sea ice coverage with actual data.
The study team
compared model simulations of past climate with observations by satellites and other instruments. They found that, on average, the models simulated a loss in September ice cover of 2.5 percent per decade from 1953 to 2006. The fastest rate of September retreat in any individual model was 5.4 percent per decade. (September marks the yearly minimum of sea ice in the Arctic.) But newly available data sets, blending early aircraft and ship reports with more recent satellite measurements that are considered more reliable than the earlier records, show that the September ice actually declined at a rate of about 7.8 percent per decade during the 1953-2006 period.
“This suggests that current model projections may in fact provide a conservative estimate of future Arctic change, and that the summer Arctic sea ice may disappear considerably earlier than IPCC projections,”
In the graphic, the red line shows the actual Artic ice melting. The blue area represents the range of melting predicted within the 18 different IPCC climate models.
In short, Artic ice melting (ice-free Artic) looks to be “30 years ahead of schedule”.
A critical gap in IPCC modeling is the basic absence of “positive feedback cycles” …
The Arctic is especially sensitive to climate change partly because regions of sea ice, which reflect sunlight back into space and provide a cooling impact, are disappearing. In contrast, darker areas of open water, which are expanding, absorb sunlight and increase temperatures. This feedback loop has played a role in the increasingly rapid loss of ice in recent years, which accelerated to 9.1 percent per decade from 1979 to 2006 according to satellite observations.
Now some might take this report in the following way:
“Well, see, the models are wrong. We don’t know enough. We must study the problem more before we take action. Let’s pay the scientists some money and go back to other things.”
This type of thinking and argument, which has been so prevalent in Global Warming Skeptic/Denier rhetoric, sabotages our ability to move toward a saner energy policy. In fact, this data should be driving us (US) toward more aggressive action.
It is correct: we don’t know enough. And, in this case, it looks like what we don’t know might very well kill us faster …