Will 2°C warming put us into the Post Fossil Fuel Age?
Limiting the average global surface temperature increase to 2°C (3.6°F) over the pre-Fossil Fuel Age average level has, since the 1990s, been commonly regarded as an adequate means of avoiding dangerous climate change, in science and policy making. But is it really? With over three-quarters of the worlds largest cities being located on the coast this is critical question.
In January 2014 we reached a .6°C (1.1°F) increase with 401ppm of CO2 in the autmosphere. Remember for over 10,000 years prior to the start of the Fossil Fuel Age CO2 levels were in the 275 ppm range. Stabilising greenhouse gas concentrations at 450 ppm would only result in a 50% likelihood of limiting global warming to 2 °C. It would be necessary to keep CO2 levels below 400 ppm to be relativelycertainty of not exceeding 2 °C.
Well-known climate scientist James Hansen and 16 other researchers, just published a report in Atmospheric Chemistry and Physics that explains there is an “amplifying feedback” as polar ice melts, because as more freshwater enters the ocean, it traps warmer sea water, which melts more ice. The effect is not included in the current Intergovernmental Panel on Climate Change (IPCC) modeling but “extensive data indicate [it] is already occurring,” according to the report.
“We are underestimating the speed at which these things are beginning to happen,” Hansen, head of the Climate Science, Awareness and Solutions Program at Columbia University’s Earth Institute, said Monday on a call with reporters.
Now this study has not been peer-reviewed. It was published in a discussion journal, which means it was published in full and peer review and revisions will be made publicly. Hansen said the urgency of the issue is why he submit the study to a discussion journal, rather than undergoing peer review, which might have taken too long especially given the United Nations’ climate talks in Paris that are happening at the end of the year.
Hansen told reporters, “The situation is more urgent than many politicians seem to realize,” he said. “What is really needed to happen requires that the major power decide we want to do this and we want to solve the problem and not just fiddle around the edges.” The negotiations of the UN's Conference of Parties (COP) in Paris are broadly structured around an attempt to limit global warming to 2°C through voluntary, agreed-upon carbon emission reductions.