The Intergovernmental Panel on Climate Change published its last report in 2007, for which it shared the Nobel Peace Prize with Al Gore. The next IPCC report is not due until 2013. In the interim, some of its lead authors have just published The Copenhagen Diagnosis to update climate science in time for the Copenhagen talks.
Before discussing specific findings of the report, I will respond in advance to the "we're all doomed!" comments that a diary of this nature will inevitably draw:
Is there a global tipping point?
A global tipping point can only occur if a net amplifying feedback becomes strong enough to produce a threshold whereby the global system is committed to a change in state, carried by its own internal dynamics. Despite much talk in the popular media about such 'runaway' climate change there is as yet no strong evidence that the Earth as a whole is near such a threshold. Instead 'amplified' climate change is a much better description of what we currently observe and project for the future.
(Report, p.44; my emphasis.)
We are not all doomed, but there is plenty of bad news. To summarize:
The new evidence to have emerged includes:
•Satellite and direct measurements now demonstrate that both the Greenland and Antarctic ice-sheets are losing mass and contributing to sea level rise at an increasing rate.
•Arctic sea-ice has melted far beyond the expectations of climate models. For example, the area of summer sea-ice melt during 2007-2009 was about 40% greater than the average projection from the 2007 IPCC Fourth Assessment Report.
•Sea level has risen more than 5 centimeters over the past 15 years, about 80% higher than IPCC projections from 2001. Accounting for ice-sheets and glaciers, global sea-level rise may exceed 1 meter by 2100, with a rise of up to 2 meters considered an upper limit by this time. This is much higher than previously projected by the IPCC. Furthermore, beyond 2100, sea level rise of several meters must be expected over the next few centuries.
•In 2008 carbon dioxide emissions from fossil fuels were ~40% higher than those in 1990. Even if emissions do not grow beyond today’s levels, within just 20 years the world will have used up the allowable emissions to have a reasonable chance of limiting warming to less than 2 degrees Celsius.
The last point is the important one for activists. "Business as usual" is estimated to reach 4-7 degrees C by 2100, "locking in climate change at a scale that would profoundly and adversely affect all of human civilization and all of the world's major ecosystems." (Report, p.51.) A goal of 2 degrees C has generally been seen as doable -- politically and technologically possible, although carrying "a significant risk of adverse impacts on ecosystems and human society." (id.) The scientists estimate that if a total of 1,000 gigatons is emitted for years 2000-2050, the likelihood of exceeding 2 degrees C is about 25%. The climate change problem can be solved, if the political will exists.
The world is burning through its carbon allowance, and needs to be put on a carbon diet. From 2000 to 2009, the world's people emitted 350 gigatons of carbon, or 35% of its total carbon emissions for 50 years in only 18% of the time. If we keep on going at this rate, we'll have used up the entire 1,000 gigaton carbon budget by 2030 and then commit the world to those adverse effects on all of human civilization. Even 2 degrees C carries some risks, which is why African nations have called for a stricter carbon diet to bring emissions down to 1.5 degrees C temperature rise. For example, a 2 degree C rise could lead to sufficient warming over Greenland to eventually melt much of its ice sheet, raising sea levels by over six meters (nearly 20 feet) and displacing hundreds of millions of people worldwide. (Report, p.51) However, actions taken in the next 5 to 10 years will determine whether the world goes on a carbon diet or whether it continues bingeing.
This morning, three principal authors of the report sounded frustrated, mystified, and bewilderd by the smear campaign that's arisen out of the now-infamous emails: There is no such thing as a Republican or Democratic ocean circulation theory, they told reporters and bloggers. The ice has no agenda. These words need to be repeated to every Republican and Democratic Senator until they pass the Kerry-Boxer climate bill to put the United States on its carbon diet. The next IPCC report, due in 2013, shouldn't have to read "everything worse than predicted, again."
Update: For some people, including me, the diary formatting goes awry around Unenergy's excellent comment. I'm unable to reply to comments and thus must hide the decline in my intellect; until the evidence of the tricky conspiracy is brought to light (yes, that's snark), please accept my apologies, and email me (address in profile) if you want to chat.
Comments are closed on this story.