During the 2009 climate talks in Copenhagen, the international community agreed to recognize that "the scientific view that the increase in global temperature should be below 2 degrees Celsius (3.6 F)." All agreed that a major policy goal would be to do everything possible to curb emissions before we reached that limit. But according to a new report out from 18 leading scientists, the agreement was overly optimistic: 2 degrees of warming is too high a threshold to avoid catastrophic climate change. A better limit, they found, would be half that.
In other words, we've been working toward the wrong goal.
Not only that, but the "acceptable" amount of emissions agreed upon by the U.N.'s Intergovernmental Panel on Climate Change this fall is wrong, too. Led by James Hansen of Columbia University, the study concluded that the IPCC's carbon budget of 1 trillion metric tons would in fact warm the atmosphere up to twice the international limit (or four times that which they say the limit should be).
But as the unsuccessful climate talks a few weeks back in Poland demonstrated, we're further off track than ever in reaching even the 2.0 degree goal. Seeing as how we've already reached 0.8 degrees warming, it seems impossible that the world could hold itself to half that. Reuters explains what would have to happen:
Warming could be held to around 1 degree C if emissions from burning fossil fuels were cut by 6 percent a year from 2013 and by reforestation, which would result in 500 billion metric tons (551.16 billion tons) of cumulative carbon in the atmosphere near the end of the century, the study said.
However, if emissions continued to grow until 2020, they would then have to be reduced by 15 percent a year to reach 500 billion metric tons.
"The huge fossil fuel energy infrastructure now in place makes it practically certain that the 500 (billion metric tons) limit will be exceeded," the study said.
According to Mother Jones, "Hansen readily admitted that such a goal is essentially unattainable."
Instead, he said, he's hoping that the paper can serve as the basis for future legal action against governments for failing to curb emissions and protect future generations. The study's assessment is damning: "Continuation of high fossil fuel emissions, given current knowledge of the consequences," the authors summarize, "would be an act of extraordinary witting intergenerational injustice."