The Trump administration has made clear it wishes to gut NOAA’s research enterprise, which is at the center of climate research globally. Against this ominous backdrop, a small group of scientists is scrambling to preserve the ability to know how much carbon dioxide is in the atmosphere. Such networks provide critical information on how fast carbon dioxide and other greenhouse gases are building up in the air from fossil-fuel burning and other processes. They provide information on how much carbon dioxide is being removed from the atmosphere by the oceans and by land plants. Hundreds of groups can measure carbon dioxide using various off-the-shelf analyzers, but these analyzers first need to be calibrated using compressed air that has a known amount of carbon dioxide in it.