National Geographic : 2004 Sep
More than a hundred million people worldwide live within three feet of mean sea level. The future breakdown of the thermoha line circulation remains a disturbing, if remote, possibility. But the link between changing atmospheric chemistry and the chang ing oceans is indisputable, says Nicholas Bates, a principal investigator for the Bermuda Atlan tic Time-series Study station, which monitors the temperature, chemical composition, and sal inity of deep-ocean water in the Sargasso Sea southeast of the Bermuda Triangle. Oceans are important sinks, or absorption centers, for carbon dioxide, and take up about a third of human-generated CO2. Data from the Bermuda monitoring programs show that CO 2 levels at the ocean surface are rising at about the same rate as atmospheric CO 2. But it is in the deeper levels where Bates has observed even greater change. In the waters between 250 and 450 meters (820 and 1,476 feet) deep, CO 2 lev els are rising at nearly twice the rate as in the surface waters. "It's not a belief system; it's an observable scientific fact," Bates says. "And it shouldn't be doing that unless something fun damental has changed in this part of the ocean." While scientists like Bates monitor changes in the oceans, others evaluate CO 2 levels in the atmosphere. In Vestmannaeyjar, Iceland, a light house attendant opens a large silver suitcase that looks like something out of a James Bond movie, telescopes out an attached 15-foot rod, and flips a switch, activating a computer that controls several motors, valves, and stopcocks. Two two and-a-half-liter flasks in the suitcase fill with ambient air. In North Africa, an Algerian monk at Assekrem does the same. Around the world, collectors like these are monitoring the cocoon of gases that compose our atmosphere and permit life as we know it to persist. When the weekly collection is done, all the flasks are sent to Boulder, Colorado. There, Pieter Tans, a Dutch-born atmospheric scien tist with NOAA's Climate Monitoring and Diagnostics Laboratory, oversees a slew of sen sitive instruments that test the air in the flasks 28 NATIONAL GEOGRAPHIC * SEPTEMBER 2004 for its chemical composition. In this way Tans helps assess the state of the world's atmosphere. By all accounts it has changed significantly in the past 150 years. Walking through the various labs filled with cylinders of standardized gas mixtures, absolute manometers, and gas chromatographs, Tans offers up a short history of atmospheric monitoring. In the late 1950s a researcher named Charles Keeling began measuring CO 2 in the atmosphere above Hawaii's 13,679-foot Mauna Loa. The first thing that caught Keeling's eye was how CO 2 Soggy Future Young Bangladeshis improvise shelter in the face of a down pour. The annual monsoon rains that sweep into southern and eastern Asia on the heels of the dry season may increase in intensity as a result of climate warming. Rising ocean temperatures could increase the incidence of cholera, and more rain could lead to crop reduc tions and increased malnutrition.