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, industrial sources, and more. The analysis finds that we already have enough carbon-emitting power plants to push up against the limits of the carbon budget, and the number of plants in the planning stages might cause us to shoot right past it.
Running the numbers
To figure out how we’re doing on the carbon budget, the researchers totaled up all the major sources of emissions, including industrial sources, cars and trucks, and power-generation plants. The annual emissions from each of these was then projected forward, accounting for things like the typical lifespan of each, their annual use (miles for cars, capacity factor for power plants, etc.), and the emissions associated with that use. You can view these as emissions we’re committed to, as they’ll happen unless we retire hardware before its usable lifetime is up.