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For more information on these science news and feature story tips, please contact the public information officer at the end of each item at (703) 292-8070. Editor: Bill Noxon Contents of this News Tip:
OCEAN pH MAY BE UNSUNG PLAYER IN CLIMATE CHANGENew research funded by the National Science Foundation (NSF)'s division of ocean sciences suggests that assumptions used for 50 years in reconstructing some aspects of earth's climate history have lacked a critical variable: fluctuations in the acid-base balance of the ocean. The discovery could help explain why atmospheric carbon dioxide has increased since the last ice age, and improve understanding of the ocean's role in global climate change. "If the changes we see in the fossil record were due to changes in the ocean's pH, it means we'll have to take a look at the ocean's carbon-buffering system as a controller of 'greenhouse gases,'" explains lead researcher Howard Spero of the University of California at Davis. "It will reinforce the notion that oceanic processes drive climate." Spero and other geologists discovered the importance of ocean pH during studies of living marine organisms called foraminifera. Many long-standing conclusions about ancient climate are based on analyses of fossil foraminifera shells. "Geologists, paleogeologists, and paleoclimatologists have been using foraminifera to reconstruct earth's climate history," says Spero. "Using this new parameter will allow us to more completely tell the story." [Cheryl Dybas] ELEVATED CO2 HELPS PLANTS SURVIVE COLD WEATHERElevated levels of carbon dioxide in the atmosphere benefit some plants by making them more tolerant of cold temperatures, researchers working through the NSF-supported National Center for Atmospheric Research in Boulder, Colo., have found. "This could mean earlier spring planting dates for some crops in the future," says David Wolfe, the project's researcher at Cornell University. "It may also affect the mixture of species in natural plant communities, because only certain plants benefit in this way." Results of research done by Wolfe and colleagues at Cornell and at the College of Charleston show "how the increase in carbon dioxide and other 'greenhouse gases' will shake up the plant world," says Wolfe. "Maps of global vegetation zones will inevitably be altered by these sorts of direct effects on plants, whether or not we also have major changes in climate." The scientists have focused thus far on two crops--beans and cucumbers--that are among a class of plants that tends to wilt when temperatures dip below about eight degrees Celsius (45 degrees Fahrenheit). The researchers knew from prior experiments that elevated carbon dioxide levels often reduce the rate of water loss from leaves, and they suspected this effect would reduce the amount of chilling damage in these species. This hypothesis was confirmed by their study: plants grown and chilled at elevated CO2 levels showed less severe wilting and suffered less permanent leaf damage than plants grown and chilled at current atmospheric CO2 concentrations. "If carbon dioxide in the atmosphere doubles within the next century, as we are expecting," adds Wolfe, "these species may be able to withstand temperatures several degrees cooler than they do now." [Cheryl Dybas] STUDY SEEKS NEW FINDS IN ANTARCTIC ICE SHEETThe Antarctic ice sheet is the earth's largest accumulation of ice. Should it melt, sea level would rise by 50 to 60 meters (some 150 to 180 feet). The Southern Ocean surrounding Antarctica consists of a ring of cold water that insulates Antarctica from warmer waters to the north, keeping this ice sheet frozen in place. The Antarctic ice sheet and adjacent Southern Ocean together form the Antarctic ocean-cryosphere system, one of the most important components of earth's climate system. A research team departed Capetown Dec. 15 aboard the world's largest scientific drill ship, the JOIDES Resolution, on an expedition to reconstruct historical climate changes in the Antarctic. Using several new methods, oceanographers will attempt to better understand the history and stability of the ice sheet. The research is funded in part by the NSF and sponsored by the international Ocean Drilling Program. "The build-up of the Antarctic Ice Sheet around 40 million years ago led to dramatic changes in earth's climate system and biosphere," says David Hodell, co-chief scientist of the expedition, and a researcher at the University of Florida. "Earth's climate changed from a relatively warm 'hothouse' to a cold 'icehouse.'" Although scientists recognize that the Southern Ocean has played a major role in defining earth's climate system, many questions remain regarding the history of climatic and oceanographic changes in this remote region. [Cheryl Dybas]
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