Key Investigators: Peter Pilewskie, Francisco P. J. Valero, Wnrran Gnra
Among the more horrific events that occurred during the Gulf War of 1991 was the igniting of the oil fields of Kuwait by invading Iraqi forces. For nearly two months, 500 oil wells burned continuously, filling the surround-ing skies with blackened smoke which blocked out the sun and turned day into night (Fig.1) . As the volume of smoke spread out over a 200 to 400 km area of the Gulf (see Fig. 2) , surface temperatures in the area dropped far below normal. The dense smoke clouds from the Kuwaiti oil fires created a barrier preventing solar energy reaching the surface of the Earth as well as preventing heat from escaping to space. Some scientists predicted significant global warming as a result of a 5% increase in emissions of carbon dioxide, a greenhouse gas. Others foresaw a nuclear winter caused by the 30+ million tons of smoke if the fires burned for a year. An assessment of the situation and a reliable prediction of the fires' environmental consequences was needed to help mitigate this situation.
As part of a multi-agency effort, atmospheric scientists from NASA's Ames Research Center installed radiometric instruments in the University of Washington C-131A aircraft. The aircraft made several flights into the smoke cloud at varying altitudes (Fig. 3) . Measuring the downward and upward transport of solar energyóas well as extinction of sunlight beneath, above, and within the smoke plumeórevealed that at times, only 8% of solar radia-tion reached the surface while 78% of the solar radiation was absorbed by particles in the smoke clouds. The instantaneous heating rate inside the smoke plume reached 24 K per day. However, results from a flight on May 18, 1991 indicated negligible effects on surface cooling or atmospheric heating on a larger, global scale.
Thus, the measurements provided evidence that these significant, climatic effects did not extend into other regions. It was determined that changes in the heating and cooling of land surface were limited to the local Persian Gulf region under the smoke cloud with its highly absorbent black carbon aerosol. Consequences of the fires were limited to the local region and the extent of this environmental catastrophe did not escalate to that of a nuclear winter phenomenon.
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