Jim Hansen, Jeffrey Sachs and a gaggle of other scientists and economists published a research paper last Tuesday titled, Assessing “Dangerous Climate Change: Required Reduction of Carbon Emissions to Protect Young People, Future Generations and Nature.” Tim Radford, former science editor for the Guardian, wrote a great article about the paper, here, that I highly recommend reading to get the gems and tenor of the research.
The big take away from the paper is that the 2°C warming ceiling set by world governments would have, quote, “disastrous consequences.” Hansen and the gang recommend limiting human-made warming to 1°C – and give quite a compelling argument. Essentially, the paper shows that 1°C warming relative to 1880-1920 keeps global temperature within the Holocene range, the current geological epoch that human life has adapted to; while warming of 2°C could cause “major dislocations for civilization.” The paper’s point is well taken, 1°C warming is safer and we only get one shot at this.
How much can we burn to stay below 1°C? Using a simple carbon model, the scientists calculate that we can burn another 130 GtC (477 Gt CO2). If we assume that emissions are growing at 2% a year we will burn through this in another 11 years. As with any calculation based on the future, there are some assumptions built in. In this case, the authors assume climate-friendly/favourable changes to land use emissions and non-CO2 forcings – meaning that the remaining budget may be even smaller than they calculated. But the message is clear, we need to limit fossil fuels CO2 emissions and fast.