We're still on track for 2 doublings of greenhouse gas concentrations by 2100
Joe Romm at Climate Progress today reported on a new International Energy Agency report showing that carbon dioxide emissions hit a new record in 2011 or 31.6 billion tons (CO2). The key point that Romm makes is that these emissions increases are consistent with the MIT no-policy case, and that means two doublings of greenhouse gas concentrations by 2100.
Students of climate science know that every doubling will likely yield 3 celsius degrees of warming, so two doublings means committing the earth to 6 celsius degrees of warming. As Cold Cash, Cool Climate points out, such increases will push the earth well outside the comfortable range in which humanity evolved (the envelope defined by the 2 celsius degree warming limit), and will raise the possibility of nasty positive feedbacks leading to even higher warming (like releasing methane hydrates from the ocean floor, melting permafrost, and burning peat bogs).
At least US carbon dioxide emissions are down 7.7% since 2006, but those improvements were offset by emissions increases in China and other developing countries. Time to get serious about global emissions reductions!
