Most of the world’s nations have agreed to limit warming to 2°C, with a stretch goal of keeping things below 1.5°C. Since we have a good sense of how carbon dioxide drives that warming, it’s possible to estimate how much more CO2 we can add to the atmosphere before those goals are exceeded. People have referred to that limit as a “carbon budget.” The budget is useful, because it allows us to evaluate different ways of keeping below it. If cars are electrified by 2030, for example, it might give us more time to figure out how to handle air travel.
Now, a group of researchers has compared that carbon budget to the existing sources of emissions from fossil fuels, including power plants,