Arctic ice beats worst case predictions

Arctic sea ice melt worst than all IPPC projections

The Arctic’s ice cover is retreating more rapidly than estimated by any of the 18 computer models used by the 2007 IPCC assessments.
Source: Arctic sea ice decline: Faster than forecast, Geophysical Research Letters vol. 34, L09501, doi:10.1029/2007GL029703, 2007]

Source: Slide 7 from: "Feedbacks in the climate system and implications for future climate projections", Presentation to ”Climate, Oceans and Policies”, Washington DC, November 1, 2005 by Tore Furevik (Geophysical Institute, University of Bergen
Bjerknes Centre for Climate Research, Bergen, Norway).

This is of great practical signifance: In 2006, predictions on the final demise of the Arctic’s floating ice were brought forward from 2080-2100 to 2040 and more recently 2030. The melting of the floating ice around the north pole is now considered unstoppable. The polar bear’s only habitant will be the zoo. Data presented at the American Geophysical Union in December 2006 suggests that the Arctic may be free of all summer ice by as early as 2030, "a positive feedback loop with dramatic implications for the entire Arctic region" according to Dr Marika Holland, because the Earth would lose a major reflective surface and so absorb more solar energy, potentially accelerating climatic change across the world. "Our hypothesis is that we’ve reached the tipping point," says Ron Lindsay of the University of Washington in Seattle. "For sea ice, the positive feedback is that increased summer melt means decreased winter growth and then even more melting the next summer, and so on". With no ice, the Arctic region will rapidly begin heating, perhaps by as much as 12 degrees, with dramatic consequences for the stability of the Greenland ice sheet, which is likely to begin irreversible melting at less than 2°C of warming and is almost certain at less than 3°C, resulting in an eventual sea level rise of seven metres.

NASA’s Prof. James Hansen in "Scientific Reticence and Sea Level Rise" identifies a ‘scientific reticence’ that "in at least some cases, hinders communication with the public about dangers of global warming… Scientific reticence may be a consequence of the scientific method.  Success in science depends on objective skepticism.  Caution, if not reticence, has its merits.  However, in a case such as ice sheet instability and sea level rise, there is a danger in excessive caution.  We may rue reticence, if it serves to lock in future disasters". The case of ice sheet disintegration at the recent IPCC meetings caused deep concern amongst scientists.
Sources: Fred Pearce, "Climate change: What the IPCC didn’t tell us", New Scientist, 9 February 2007; McKie, R.,
"Scientists challenge ‘cautious’ UN report", The Observer, 28 January 2007
Little time to avoid big thaw, scientists warn

Emissions rises

CO2 emissions from fossil-fuel burning and industrial processes have been accelerating at a global scale, with their growth rate increasing from 1.1 percent/year for 1990-1999 to >3 percent/year for 2000-2004. The emissions growth rate since 2000 was greater than for the most fossil-fuel intensive of the Intergovernmental Panel on Climate Change emissions scenarios (known as "business as usual") developed in the late 1990s.
Source: Global and regional drivers of accelerating CO2 emissions

As well New Scientist reports that the temperature rise from 1990 to 2005 — 0.33°C — was "near the top end of the range" of IPCC climate model predictions.

Is the IPCC process dangerously conservative?

The summaries of the IPCC research, known as Summary for Policy Makers (SPMs), are subject to political interference. The IPCC process is bogged down in line-by-line negotiations by government representatives from around the world that produces a lowest-common-demoninator, conservative report. British researchers who saw drafts of the February 2007 IPCC Working Group 1 SPM claim it was significantly watered down when governments became involved in writing it. As early as the IPCC’s first report in 1990, US, Saudi and Soviet delegations acted in “watering down the sense of the alarm in the wording, beefing up the aura of uncertainty” (Jeremy Leggett, "The Carbon War: Global Warming and the End of the Oil Era" 2001, p 15).

Reflecting this reticence, a number of impact events are occuring more rapidly than the IPCC reports. For example, whilst recent research supports climate science models which say that the earth’s carbon sink is weakening, the 2007 IPCC WG1 says "Models used to date do not include uncertainties in climate-carbon cycle feedback… because a basis in published literature is lacking… Climate-carbon cycle coupling is expected to add carbon dioxide to the atmosphere as the climate system warms, but the magnitude of this feedback is uncertain".

Compiled by David Spratt
3 September 2007

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