Monday, September 22, 2014

World Could Surpass 2 C Temperature Rise in 30 Years, Researchers Say

The IPCC's Fifth Assessment Report collated from the peer-reviewed literature almost 1200 scenarios of future emissions, each scenario having a different 'story' of how the future might unfold. The scenarios can be grouped according to which of the four Representative Concentration Pathways (RCPs) they are most similar to, based on peak concentration of greenhouse gases.  (Credit: CICERO) Click to enlarge.
Human activities added 1,430 gigatons of carbon to the atmosphere from 1870 to 2013.  That's 45 percent of the total carbon budget the world has to maintain a rise in global temperatures below 2 degrees Celsius.  At this rate of emissions, the world will hit its carbon quota in the next three decades.

The numbers were reported by the Global Carbon Project, an international consortium of scientists who track the total accumulation of carbon annually, in a series of articles in the journals Nature Climate Change, Nature Geoscience and Earth System Science Data Discussions.

The reports are meant to guide policymakers to a new way of thinking about emissions ahead of the New York climate summit this week.  Policymakers are trying to hash out a new global agreement by 2015 following the expiration of the Kyoto Protocol last year.  Some consider Kyoto a failure as the world's emissions trajectory remains poised to increase global temperatures by 3.2 to 5.4 C in 2100.

Some scientists are suggesting that policymakers approach emissions reductions in a different way.  In recent research, scientists have identified that the world can altogether emit 3,200 gigatons of carbon dioxide and still keep temperature rise below 2 C.  Of that, we have already emitted 1,430 gigatons from 1870 to today.

This leaves roughly 1,770 gigatons of carbon dioxide, which should be split up among the nations, according to scientists at the Global Carbon Project.

"We are nowhere near the commitments necessary to stay below 2°C of climate change, a level that will be already challenging to manage for most countries around the world, even for rich nations," Corinne Le Quéré, director of the Tyndall Centre at the University of East Anglia, said in a statement.  "Politicians meeting in New York need to think very carefully about their diminishing choices exposed by climate science."

The approach is diametrically opposite to the one policymakers currently favor, in which nations choose to make emissions reductions below a base line.  For example, the United States' mitigation target is 17 percent below 2005 levels by 2020.

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