Spotting the world's polluters from space

摘要

A pair of satellites will soon take on the politically charged task of measuring carbon dioxide emissions. They could eventually help determine whether nations are meeting their emission targets and guide future climate-change negotiations. The total amount of CO_2 in the atmosphere is calculated from ground-based measurements taken at the 100 or so CO_2-monitoring stations scattered around the world. These measurements show that about half of the CO_2 emitted from burning fossil fuels is absorbed by carbon sinks such as forests and oceans. But it is unclear exactly where and how large the sinks are. And if they shut down for some reason, climate change could accelerate dramatically.