The Chinese government took drastic measures to clean up the air quality ahead of the games, cutting industrial activity by 30 percent, halting all construction and reducing the number of cars on the road by half. The “great shutdown” has not only provided one San Diego scientist a unique opportunity to study human impact on the planet’s surface temperature on a scale that may never be repeated again, it also has the potential to directly impact San Diego’s climate in the coming weeks.
Professor V. Ramanathan is a distinguished professor of atmospheric sciences and the director of the Center for Atmospheric Sciences (CAS) at the Scripps Institution of Oceanography (SIO) at University of California, San Diego (UCSD). He says that the Olympic organizers and the Chinese government have provided a huge and unprecedented opportunity to see what happens when a heavily industrialized region drastically reduces it’s daily emissions.
Drawing an analogy between the current global warming debate and the controversy that followed the first studies to link cigarette smoking and lung cancer Ramanathan says “Imagine that you have a population of cigarette smokers and that you are able to suddenly stop half of them from smoking to see what happens.” The “great shutdown” that China has imposed ahead of the games provides just such an opportunity to observe the impact of human activity on global warming. “It’s a golden opportunity to get some incredible data. I think that such a study, on such a huge scale will never be repeated”, he says.
As part of the Cheju ABC Plume-Monsoon Experiment (CAPMEX), Ramanathan and his team will fly instrument laden Autonomous Unmanned Air Vehicles (AUAV) into the projected path of pollution plumes coming from Beijing over the next eight weeks. The aircraft are small, weighing only sixty pounds with a wingspan of roughly eight feet and are powered by an engine similar to a lawn mower engine. “The engines are located under the back of the aircraft and the instruments that measure the pollution are located on the front. “That way we are sure that we are not measuring our own exhaust” says Ramanathan.
The flights will originate from Cheju, a small island in the Korea Strait, located about 725 miles southeast of Beijing. The initial test flights began on August 9th and the experiment is scheduled to run through Sept. 30. The missions will fly in airspace that is not in use by civilian or military aircraft and although the flight paths are preprogrammed, the AUAVs the ground crew has the ability to intercede and change course at any time.
The fact that the AUAVs will be flying from Korea and not in China or closer to Beijing naturally leads to questions about whether there may be some political reason for the origin of the flights. Ramanathan quickly dispels any such notions though. AUAV flights over populated areas are restricted even in the US where his group is currently flying regular missions from Edwards Air Force Base as part of the California AUAV Air Pollution Profiling Study, (CAPPS). Besides, “at 10,000ft we are sampling air from sources over a 1,000 miles away” says Ramanathan. Thus, “the question of flying over China or Chinese airspace never arose”, he says.
NASA satellites will be recording data in the same study area as the AUAV missions and ground observations will be made in the area at the same time. Satellite studies of the source of air pollution in the region have been ongoing for many years, “particularly from sources in China and Beijing”, says Ramanathan. “The experiment will provide an opportunity to validate those studies with the aircraft and ground observations”. He says that the Korean government has invested roughly half a million dollars in the instrumentation used to make the ground observations that began on August 1st and that three Korean scientists will take part in the experiment.
At the same time, back in California, simultaneous AUAV missions being conducted as part of the nine-month-long CAPPS survey of air pollution over Southern California will be collecting similar atmospheric data. Comparison of the two data sets will help to answer the question of how much of the air pollution from China ends up downwind, over California and San Diego. What impact those sources have on the region’s air quality climate is of increasing interest. The increasing intensity of winter storms in California in recent years may well be one example of the impact according to Ramanathan.
Numerous studies have confirmed the ill effects on human health of suspended black carbon or soot from the burning of coal, diesel fuel and wood and there is no question that they have a significant impact says Ramanathan. But besides the health implications the presence of these aerosols in the atmosphere has the potential to greatly affect the global climate. The Indian Ocean Experiment (INDOX) was a large experiment headed by Ramanathan that led to the discovery of a haze of air pollution 3-km thick lying over most of the Arabian Sea, Bay of Bengal, and the Indian subcontinent, spreading across an area larger than the continental States. This atmospheric brown cloud (ABC) is filled with black carbon that threaten to reduce rainfall, dry the planet’s surface, cool its tropics, and stifle its rainfall.
The study found that the brown cloud blocks out the sunlight, reducing evaporation and rainfall. The black carbon particles absorb and scatter the sunlight, reducing the amount of heat reaching the surface. The atmospheric heating creates an inversion - where temperatures at higher elevations are greater than those near the surface - that inhibits normal convection and rainfall. The reduction in sunlight reaching the surface has a cooling effect that results in less evaporation from the land and ocean, which in turn leads to a reduction in rainfall.
The fact that the suspended pollutants are having a cooling effect on the planet’s surface may be masking the effects of global warming. Ramanathan and others think that the climate change will accelerate when the air pollutants are removed. It’s an unfortunate coincidence that they have a cooling effect on the planet’s surface and at the same are a major contributor to global warming.
In Beijing the affects of shutting down factories, stopping all construction and removing 2 million cars from the streets seem evident to many attending the games. Haile Gebrselassie, the Ethiopian marathon record-holder, who pulled out of the Beijing race in March citing fears that the pollution could affect his asthma spoke to Reuters news service on Monday last. "I'm surprised. What do you expect from me? I was here in February, I didn't see no blue sky," he said beneath sunny skies in the Chinese capital. "Since I came here everything is perfect."
Independent informal smog measurements by news agencies Associated Press (AP) and the British Broadcasting Company (BBC) show dramatic reductions in suspended particles detected in the air over Beijing since the games began. A rainstorm during the first week appears to have helped to clear out a lot of the pollutants from before the “great shutdown” began. While the connection between reduced human activity and a reduction in air pollution may seem obvious, the question of what the long term affects of suspended soot in the atmosphere will have on the global climate and our own Southern California climate remain. Ramanathan and the other researchers will be trying to unravel that puzzle over the coming months as they study the data from the AUAV flights originating in Korea and California. “The effects of soot reductions during the Olympics on atmospheric heating”, says Ramanathan, “provide a golden opportunity to gain much needed insights into the magnitude of future global warming”.
Copyright Ronan Gray, 2008, 2009. All rights reserved. No reproduction without prior written permission.