Scientists work to put the greenhouse gas in its place
One morning each week, a scientist takes a stroll on the barren upper slopes of Hawaii’s Mauna Loa volcano, a basketball-sized glass sphere in hand. At some point, the researcher faces the wind, takes a deep breath, holds it and strides forward while twisting open a stopcock. With a whoosh lasting no more than a few seconds, 5 liters of the most pristine air on the planet replaces the vacuum inside the thick-walled orb.
Once every couple of weeks, a parka-clad researcher at the South Pole conducts the same ritual. At these remote sites and dozens of others, instruments also sniff the air, adding measurements of atmospheric chemistry to a dataset that stretches back more than 50 years. The nearly continuous record results from one of the longest-running, most comprehensive earth science experiments in history, says Ralph F. Keeling, a climate scientist at Scripps Institution of Oceanography in La