Think of the sky as a big bowl of blue soup. Its ingredients include oxygen, nitrogen, and carbon dioxide, which scientists can precisely measure. But ever since the Industrial Revolution, humans have been adding heaps of extra CO2 by burning fossil fuels, warming the planet 1.2 degrees Celsius so far and complicating those calculations.
While it’s easy enough to know how much total CO2 is in that atmospheric soup, it’s difficult to parse how much humanity is adding at any given time. That’s because Earth’s natural processes also create the gas, and because there are such a multitude of sources for civilization’s own emissions, some of which grow or wane by the hour. It would be like throwing dashes of salt into actual soup and then trying to count precisely how many grains went in after they hit the liquid.
What atmospheric scientists can do, though, is make an…
