2˚C target for climate talks is 1˚ too high: Jim Hansen + 17 scientists.

RTCC: “Governments have set the wrong target to limit climate change. The goal at present – to limit global warming to a maximum of 2°C higher than the average for most of human history  – “would have consequences that can be described as disastrous”, say 18 scientists in a review paper in the journal PLOS One.” “With a 2°C increase, “sea level rise of several meters could be expected,” they say.  “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.
The paper’s lead author is James Hansen, now at Columbia University, New York, and the former NASA scientist who in 1988 put global warming on the world’s front pages by telling a US government committee that “It’s time to stop waffling so much and say the evidence is pretty strong that the greenhouse effect is here.”
Hansen’s fellow authors include the economist Jeffrey Sachs of Columbia University and the biologist Camille Parmesan, of the University of Plymouth in the UK and the University of Texas at Austin, USA.
Their argument is that humanity and nature – “the modern world as we know it” – is adapted to what scientists call the Holocene climate that has existed for more than 10,000 years – since the end of the Ice Age, the beginnings of agriculture and the first settlement of the cities.
Warming of 1°C relative to 1880–1920 keeps global temperature close to the Holocene range, but warming of 2°C, could cause “major dislocations for civilization.”
….“However the stark reality is that global emissions have accelerated, and new efforts are underway to massively expand fossil fuel extractions by drilling to increasing ocean depths and into the Arctic, squeezing oil from tar sands and tar shale, hydro-fracking to expand extraction of natural gas, developing exploitation of methane hydrates and mining of coal via mountain-top removal and mechanised long wall-mining.”
Therefore the scientists make a case for limiting overall global carbon emissions to 500 gigatonnes rather than the 1,000 billion tonnes in the 2°C rise scenario.”