By Joe Romm on December 3, 2013 at 5:04 pm
“350 Or Bust: Scientists Warn Even 2°C Warming Leads To ‘Disastrous Consequences’ And Must Be Avoided“
Humanity is choosing to destroy a livable climate, warn 18 of the world’s leading climate experts in a new study. Led by James Hansen, they make the strongest case to date for a target of 350 parts per million (ppm) of CO2 in the air, or about 1°C (1.8°F) total warming.
Yes, we are already near 400 ppm (and rising 2 ppm a year), and have warmed more than 0.8°C since preindustrial times, so the authors understand the challenge. But in their must-read article in the journal PLOS One, the scientists argue that “aiming for the 2°C [3.6°F pathway would be foolhardy” because it “would have consequences that can be described as disastrous”:
… sea level rise of several meters could be expected. Increased climate extremes, already apparent at 0.8°C warming, would be more severe. Coral reefs and associated species, already stressed with current conditions, would be decimated by increased acidification, temperature and sea level rise. More generally, humanity and nature, the modern world as we know it, is adapted to the Holocene climate that has existed more than 10,000 years.
They point that even a modest temperature rise will end the stable climate that enabled modern civilization is clear in this figure derived from another recent study:
Temperature change over past 11,300 years (in blue, via Science, 2013) plus projected warming this century on humanity’s current emissions path (in red, via recent literature).
A key point of the new study — bluntly titled “Assessing ‘Dangerous Climate Change’: Required Reduction of Carbon Emissions to Protect Young People, Future Generations and Nature” — is that 2°C warming is unlikely to be stable because it “would spur ‘slow’ feedbacks and eventual warming of 3–4°C with disastrous consequences.”
As Climate Progress has previously reported, the thawing permafrost alone is projected to add as much as 1.5°F (!) to total global warming by 2100 and ocean acidification could add another 0.9°F.
Global Climate Change http://courses.dce.harvard.edu/~envre130
Environmental Justice http://courses.dce.harvard.edu/~envre145
Environment Ethics http://courses.dce.harvard.edu/~envre120