Climate scientists at CarbonBrief examined how long we have left before depleting our collective carbon budget, and they don’t have encouraging news. These budgets gauge the amount of carbon emissions humans can pump into the atmosphere before temperatures rise 1.5 degrees, 2 degrees, and 3 degrees Celsius greater than pre-Industrial Revolution levels.
For their analysis, CarbonBrief utilized carbon budgets prepared by the Intergovernmental Panel on Climate Change (IPCC). For each temperature increase, IPCC created three budgets, each of which includes how likely we are to meet said budgets. The first offers a 66 percent chance, the second 50 percent, and the third 33 percent. CarbonBrief clarifies that those statistics aren’t probabilities but rather “the proportion of all the model simulations that keep warming below the temperature limit.”
CarbonBrief zeroed in on the 66 percent chance of staying below the 1.5 degree limit. They then incorporated recent data from the Global Carbon Project, which revealed we may have only 5 years until we use up our carbon budget and hit the 1.5 degree mark.
2015 global emissions reached 39.7 billion metric tons due to “fossil fuel burning, cement production, and land use change.” That was down from 40.3 billion metric tons in 2014. Yet in 2011, the optimistic 66 percent 1.5 degree budget only allowed for 400 billion metric tons, so adding up emissions from all the years since then means we only have around 205 billion metric tons left in the budget. Projecting into the future, CarbonBrief suggests we may use up our budget by 2021.
The 66 percent chance budgets for 2 degrees and 3 degrees are slightly more hopeful, to be reached in just over 20 years and 55 and a half years, respectively, but some scientists have argued that 2 degrees is too much, and at that point our planet will suffer irreparable effects of climate change.
Even if we could stop all emissions tomorrow, the Earth would continue to warm for several years. Energy Research Scholar for the International Institute for Applied Systems Analysis Joeri Rogelj said, “…these budgets are a bit of an overestimate of the carbon we have left to burn because temperatures would continue to warm for about a decade after we stopped emitting CO2.”
Images and animation via CarbonBrief