If we choose to put the future of our species at severe risk, why does our species deserve to exist?http://thinkprogress.org/climate/2013/09/17/1892241/hansen-climate-sensitivity-uninhabitable/
By Joe Romm on September 17, 2013
James Hansen, the country’s most prescient climatologist, is out with another must-read paper, “Climate sensitivity, sea level and atmospheric carbon dioxide.” The paper, co-authored by a number of Hansen’s former colleagues at NASA, is an antidote to the rosy scenarios the mainstream media have recently been pushing.
The key findings are
The Earth’s actual sensitivity to a doubling of CO2 levels from preindustrial levels (to 550 ppm) — including slow feedbacks — is likely to be larger than 3–4°C (5.4-7.2°F).
Given that we are headed towards a tripling (820 ppm) or quadrupling (1100 ppm) of atmospheric CO2 levels, inaction is untenable.
“Burning all fossil fuels” would warm land areas on average about 20°C (36°F) and warm the poles a stunning 30°C (54°F). This “would make most of the planet uninhabitable by humans, thus calling into question strategies that emphasize adaptation to climate change.”
Burning all or even most fossil fuels would be a true scorched Earth policy.
Given that James Hansen has been right about global warming for more than 3 decades, his climate warnings need to be taken seriously.
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If we stay anywhere near our current emissions path, we face catastrophic levels of warming.
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Hansen et al. note that this may not even require burning all of fossil fuels. It could happen on our current emissions path — if the slower (decadal) feedbacks are as strong as some paleoclimate analysis suggests. Back in 2011 we reported on a paleoclimate paper in Science that found we are headed towards CO2 levels in 2100 last seen when the Earth was 29°F (16°C) hotter.
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