One degree Celsius.
According to Mark Lynas, the effects of (up to) just one Celsius degree of warming can be dramatic.
Lynas's 2008 book Six Degrees: Our Future On A Hotter Planet surveys the peer-reviewed scientific research to describe how our planet would change with each degree of warming from 1 to 6 degree Celsius. Lynas chose to examine this range because of the Intergovernmental Panel on Climate Change's 2001 Third Assessment Report, which predicted between 1.4 and 5.8 degrees C (2.6 to 10.4 degrees F) of global warming by the year 2100 (p. 21). Chapter one shares a title with this diary, and details the effects of zero to one degree of global warming. What does it describe?
Among other things... drought.
Not an intermittent drought as we are seeing this summer, but "perennial droughts" in the western United States. Because the thin soil of the Great Plains is underlain with sand, when the plant life disappears due to drought or over-grazing, the sands can start blowing, as they did in the Dust Bowl years of the Great Depression. Less than one degree of warming could "devastat[e] agriculture and driv[e] out human inhabitants on a scale far larger than the 1930s calamity"(pp. 29-30).
I'm not saying we're there. There's not enough evidence to make such a claim. By definition, a new normal in climate would require years if not decades of data to prove. But listening to drought news on the radio... seeing newspaper pictures of governors holding ears of desiccated corn... reading diaries here at DailyKos about lifetime firsts in dryness and heat... all I can think is, this sounds familiar.
The American discourse about anthropogenic (human-made) global warming is flawed. Even, sometimes, the discourse here. Putting the denialists to the side, the debate is cast as a choice between "the planet" and economic interests. As if the planet were some abstraction. As if it were some other planet, not the one we're living on. As if the choice were polar bears vs. jobs.
The choice is, how much privation, suffering, and death we are going to inflict on ourselves in the coming decades.
And it's not an elite issue. As crops are lost and food prices rise as a result, it should surprise no one that the effects of global warming -- droughts, floods, heat waves, more powerful storms -- will hit the poor the hardest. The global poor worst of all. But again, you don't have to care about distant famine. The price of staple foods are set to rise here in the U.S. this summer due to the current drought.
In order to stop the worst effects of runaway global warming predicted by scientists, we have to drastically reduce our greenhouse gas emissions. We have to do it now. Whether this or that government policy will get us there can be debated. But don't imagine that doing nothing will protect you. Or indeed any portion of the 99%. Because it won't.
You don't have to give a damn about polar bears. You don't have to believe that coral reefs have inherent value. It doesn't matter if you care about the Costa Rican golden toad, and it's too late if you do; global warming has caused it to go extinct (p. 63). You don't have to think of the grandchildren, your own or someone else's. Pure self-interest is enough.
Lynas, Mark. Six Degrees: Our Future On A Hotter Planet. Washington, D.C.: The National Geographic Society by arrangement with HarperCollins Ltd, 2008.