News Archive

The Global Change Data and Information System (GCDIS) Conference Calendar is a comprehensive listing of conferences, meetings, symposia, and workshops having relevance to global change. All conferences can be listed by date or alphabetically. In addition, a search function allows for finding conferences by subject area or date. The calendar is maintained for the GCDIS by NASA's Global Change Master Directory.

global change research
Ice and Mud Point to CO₂ Role in Glacial Cycle
The rhythmic stretching of Earth's orbit seems to drive glacial cycles, but how this feeble "orbital variation" could cascade through the climate system of air, land, water, and ice to produce the monstrous climate shifts of the ice ages has remained a mystery. In the 15 September issue of Science, a paleoceanographer finds a likely strongman to transmit and enforce the orbital variations' demands: carbon dioxide. Comparing records preserved in deep-sea muds with those in antarctic ice, he finds that orbital variations may muster carbon dioxide into and out of the atmosphere, and the resulting waxing and waning of greenhouse warming may drive the glacial cycle.

The entire article is available on-line for subscribers to Science Online.

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EPA Releases Report on U.S. Greenhouse Gas Emissions
Report covers emissions and sinks from 1990-1998
The U.S. Environmental Protection Agency has posted the report U.S. Greenhouse Gas Emissions and Sinks: 1990-1998 on its Global Warming Site. This report is required of the United States under its responsibilities as a Party to the Framework Convention on Climate Change, established in April 1992 by the Rio Treaty (Earth Summit). Under the Framework Convention, the United States and other developed countries agreed to submit greenhouse gas emissions reports annually to the Secretariat of the Convention.

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NOAA Announces Launch of New Global Climate Prediction Project
Ocean stewardship cited as a national priority
The first of several probes is being launched into the oceans to help weather forecasters and scientists better understand the world's climates, announced U.S. Commerce Secretary Norman Y. Mineta. The Argo Ocean Profiling Network is an international effort to collect and share information on the temperature, currents, and salinity-or saltiness-of the world's oceans that will be used to better predict the influence of events such as El Niño and La Niña on our seasonal climate. The U.S. has committed to providing at least one-third of the 3,000 float network over the next three years. The oceans are an indispensable link to our daily lives and America's prosperity," Secretary Mineta said. "To continue to reap the oceans' riches, yet preserve their fragile assets for future generations, we must consider a course change that includes, exploration, protection, and education."

global change research
Worsening Urban Air Pollution Won't Increase Global Temperature Over Next 100 Years
Researchers at the Massachusetts Institute of Technology have found that although urban air pollution is expected to increase significantly in the coming century, it will not have a big effect on global temperature change. While there may be temperature increases in certain regions, global mean surface temperature will not go up significantly because of urban air pollution, researchers at MIT's Joint Program on the Science and Policy of Global Change wrote in a paper to be published in the September 27 issue of the Journal of Geophysical Research--Atmospheres according to a press release from the American Geophysical Union. Using a method that allows global coupled-chemistry climate models to take urban air pollution into account in a new way, MIT researchers found that compared to a reference run excluding urban air pollution, the average tropospheric ozone concentration decreases while high concentrations of ozone are projected in the urban areas. As a consequence of the change in the chemical composition of the troposphere, the lifetime of methane increases. This leads to higher ambient methane concentrations, even if emissions are unaltered. As ozone decreases and methane increases, the net effect on the radiative budget of the Earth is small, because the contributions from these two greenhouse gases partially cancel each other out.

Ice cores drilled through a glacier more than four miles up in the Himalayan Mountains have yielded a highly detailed record of the last 1,000 years of earth's climate in the high Tibetan Plateau. Based on an analysis of the ice, both the last decade and the last 50 years were the warmest in 1,000 years. The core also showed a clear record of at least eight major droughts caused by a failure of the South Asian Monsoon, the worst of these a catastrophic seven-year-long dry spell that cost the lives of more than 600,000 people. The new findings, published in Science and described in an Ohio State University press release, outline data recovered from three cores drilled through the Dasuopu Glacier, a two-kilometer-wide ice field that straddles a flat area on the flank of Xixabangma, a 26,293-foot (8,014-meter) peak on the southern rim of the Tibetan Plateau. The international team, including American, Chinese, Peruvian, Russian and Nepalese members, retrieved the cores during a 10-week, 1997 expedition to the region.

The entire article is available on-line for subscribers to Science Online.

global change research
El Niño Cycles Linked to Cholera Outbreaks
Cornell Ecologist's Climate-Disease Model Shows Link
About 11 months after the start of an El Niño event in the equatorial Pacific, hospitals thousands of miles away in Bangladesh can expect a surge of cholera cases, according to the first mathematical model to link climatic cycles with subsequent cholera outbreaks. Details of the climate-disease model are reported in the 8 September issue of the journal Science by ecologists at Cornell University and the universities of Barcelona, Maryland and London. An accompanying press release from Cornell University summarizes their work. "So far we aren't seeing a return to the time when cholera was such a scourge on humanity," says Stephen P. Ellner, professor of ecology and evolutionary biology at Cornell. "But we are getting an explanation for outbreaks of cholera and diarrheal diseases in South America and the recent, higher-than-historic levels of cholera in South America and Asia." Peaks in cholera incidence at the Bangladesh hospital were found to occur every 3.7 years -- exactly the same frequency as of ENSO events between 1980 and 1998. But the cholera outbreaks and ENSO events did not precisely coincide: The scientists found an 11-month time lag from the start of an ENSO event near the equator and a peak in cholera incidence.

The entire article is available on-line for subscribers to Science Online.

global change research
Shorter Lake and River Ice Seasons Point to Global Warming
Studying climate observations from dozens of sites in the Northern Hemisphere, an international team of researchers concluded that temperatures have risen steadily for at least 150 years. Records from riverboat captains, Shinto monks and others dating to the 15th century confirm a dramatic warming trend in the Earth's recent history, scientists report in the 8 September issue of Science. Freeze and breakup dates of ice on lakes and rivers provide consistent evidence of later freezing and earlier breakup around the Northern Hemisphere from 1846 to 1995. Over these 150 years, changes in freeze dates averaged 5.8 days per 100 years later, and changes in breakup dates averaged 6.5 days per 100 years earlier; these translate to increasing air temperatures of about 1.2°C per 100 years. Interannual variability in both freeze and breakup dates has increased since 1950. A few longer time series reveal reduced ice cover (a warming trend) beginning as early as the 16th century, with increasing rates of change after about 1850.

The entire article is available on-line for subscribers to Science Online.

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Largest-Ever Ozone Hole Observed Over Antarctica
A NASA spectrometer has detected an Antarctic ozone "hole" (what scientists call an "ozone depletion area") that is three times larger than the entire land mass of the United States--the largest such area ever observed, according to a NASA press release. The "hole" expanded to a record size of approximately 11 million square miles (28.3 million square kilometers) on Sept. 3, 2000. The previous record was approximately 10.5 million square miles (27.2 million square km) on Sept. 19, 1998. The ozone hole's size currently has stabilized, but the low levels in its interior continue to fall. The lowest readings in the ozone hole are typically observed in late September or early October each year. "These observations reinforce concerns about the frailty of Earth's ozone layer. Although production of ozone-destroying gases has been curtailed under international agreements, concentrations of the gases in the stratosphere are only now reaching their peak. Due to their long persistence in the atmosphere, it will be many decades before the ozone hole is no longer an annual occurrence," said Dr. Michael J. Kurylo, manager of the Upper Atmosphere Research Program, NASA Headquarters, Washington, DC.

While evidence of the 1997-1998 El Niño was readily apparent on land-with storms and flooding that caused millions of dollars in damage-new studies have detailed El Niño's extensive consequences in the ocean environment. New evidence produced by researchers at Scripps Institution of Oceanography at the University of California, San Diego, shows that warm, nutrient-depleted waters ushered in during the El Niño resulted in a reduction in phytoplankton-the plants that are the base of the marine ecosystem, according to a press release from Scripps. Using high resolution, color-sensitive images from U.S. and Japanese satellites, Mati Kahru and Greg Mitchell report in the 15 September issue of Geophysical Research Letters that the 1997-1998 event-one of the strongest El Niños on record-supplanted the normal upwelling of cold, nutrient-rich waters in the California Current System.

Past efforts to model the potential effects of greenhouse warming on global ecosystems have focussed on flows of energy and matter through ecosystems rather than on the species that make up ecosystems. In its new report entitled Global Warming and Terrestrial Biodiversity Decline, the World Wildlife Fund used models that simulate global climate and vegetation change to investigate three important threats to global terrestrial biodiversity:

• Rates of global warming that may exceed the migration capabilities of species
• Losses of existing habitat during progressive shifts of climatic conditions
• Reductions in species diversity as a result of reductions in habitat patch size.

global change research
New Temperature Analysis Should Aid Climate-Change Studies
In a new study expected to improve predictions of global climate change, microscopic fossil shells from the deep ocean floor show that prehistoric temperature shifts in the tropical Pacific Ocean correlate closely with the birth and death of ice ages, says a University of California press release. "One of the key questions is, when we go back tens to hundreds of thousands of years, what regions of the planet are responsible for triggering glacial periods?" said Howard Spero, a UC Davis professor of geology. "One hypothesis argues that changes in high latitudes, near the poles, are responsible. The other camp argues that the tropics is the key player because it is the primary source of moisture and heat to the atmosphere. "We believe we have the smoking gun: the trace mineral content in the shells of these fossilized planktonic foraminifera, which acts as a geochemical thermometer. And the smoking gun supports the hypothesis that the tropics is a very important control on global climate change." Spero is co-author of the study published in Science with geology professor David Lea and research geologist Dorothy Pak of UC Santa Barbara.

The entire article is available on-line for subscribers to Science Online.

global change data
CO₂ Emissions Estimates Data Available
CDIAC releases dataset for 1751-1997
The U.S. Department of Energy's Carbon Dioxide Information Analysis Center (CDIAC) has released 1751-1997 estimates of CO₂ emissions from fossil-fuel combustion and cement production on global, regional, and national scales as dataset NDP-030. The 1997 estimate for global CO₂ emissions, 6601 million metric tons of carbon, is the highest fossil-fuel emission estimate ever. The 1997 estimate represents a 1.3% increase over 1996, continuing a trend of modest growth since a 1991-1993 decline in global CO₂ emissions.

El Niño, La Niña, move over. NOAA scientists and their colleagues are looking at another pattern in the world's climate, this one focused in the North Atlantic and lasting about seven decades, according to a NOAA press release. In a paper to be published in the September issue of the journal Climate Dynamics, scientists at NOAA's Geophysical Fluid Dynamics Laboratory in Princeton, N.J., and the University of Virginia explain their work with computer models trying to simulate observed changes in the sea surface temperatures over the North Atlantic. "The results from our computer models agree with what can be seen in the observed climate system," said Thomas Delworth, a GFDL meteorologist. "There appears to be a distinct temperature swing that lasts about 70 years. What we still need to look at how this affects the ocean-atmosphere relationship and ultimately, our climate and its future changes."

global change research
New View on the Culprits of Climate Change
Global Warming in the Twenty-First Century: An Alternative Scenario
For many years, researchers agreed that climate change was triggered by greenhouse gases, with carbon dioxide (CO₂) from burning of fossil fuels such as coal, oil, and gas, playing the biggest role. However, new research suggests fossil fuel burning may not be as important in the mechanics of climate change as previously thought. NASA-funded research by Dr. James Hansen of the Goddard Institute for Space Studies, New York, NY, and his colleagues, suggests that climate change in recent decades has been mainly caused by air pollution containing non-CO₂ greenhouse gases, particularly tropospheric ozone, methane, chlorofluorocarbons (CFCs), and black carbon (soot) particles. Since 1975, global surface temperatures have increased by about 0.9° Fahrenheit, a trend that has taken global temperatures to their highest level in the past millennium. "Our estimates of global climate forcings, or factors that promote warming, indicate that it is the processes producing non-CO₂ greenhouse gases that have been more significant in climate change," Hansen said in a recent NASA press release. Hansen's paper, "Global Warming in the 21st Century: An Alternative Scenario," appears in the 29 August edition of the Proceedings of the National Academy of Sceinces (PNAS).

The entire paper is available on-line.

After three years of El Niño and La Niña with their often devastating climate consequences, the Pacific is finally calming down in the tropics but still shows signs of being abnormal elsewhere, according to the latest satellite data from the U.S.-French TOPEX/Poseidon mission. These data, taken during a 10-day cycle of collection ending August 17, show that tropical Pacific sea levels, which indicate how much heat is stored in the ocean, have returned to near-normal (green) after three years of dramatic fluctuations. More information is available at NASA Jet Propulsion Laboratory's El Niño Webpage.

A new environmental satellite, NOAA-L, was planned for launch September 20 from Vandenberg Air Force Base, Calif., according to a joint NOAA and NASA announcement released August 29. NOAA-L will lift off aboard an Air Force Titan II launch vehicle at 3:22 a.m. PDT (6:22 a.m. EDT). The launch window extends for approximately 10 minutes. "The NOAA-L satellite will improve weather forecasting and monitor environmental events around the world," said Commerce Secretary Norman Y. Mineta. "The satellite will continue the support of the international COSPAS-SARSAT system by providing search and rescue capabilities essential for detection and location of ships, aircraft, and people in distress," Mineta added. NOAA-L is the second in a series of five Polar Operational Environmental Satellites (POES) with improved imaging and sounding capabilities that will operate over the next 12 years. Like other NOAA satellites, NOAA-L will collect meteorological data and transmit the information to users around the world to enhance weather forecasting. The data will be used primarily by NOAA's National Weather Service for its long-range weather and climate forecasts.

A new way of accessing and downloading images, animations and visualizations of the Earth is now available: Visible Earth. VE is a growing, central index of Earth science-related images being produced by several NASA projects including Terra and SeaWiFS. Images are categorized by location, satellite, and topic, and are also searchable using a full-text search engine. New images are uploaded daily and highlighted on the front page, so be sure to come back often!

global change research
A Simple Model for the Formation of Ice Clouds
Atmospheric ice clouds strongly affect both the chemistry and the radiant properties of the Earth. However, the formation of ice particles in the atmosphere through homogeneous ice nucleation is not fully understood. This is due to the fact that ice forms in aqueous aerosol droplets which can be composed of a great variety of constituents. Scientists from the Federal Institute of Technology Zurich (Switzerland) and the Max Planck Institute for Chemistry in Mainz (Germany) show that the formation of atmospheric ice particles can be described by a general thermodynamic model in a paper carried in the 10 August issue of Nature, according to a press release from the Max Planck Society. Using laboratory data on a large number of solutes, they show that ice nucleation is independent of the nature of the solute. The only important parameters required to describe ice particle formation are temperature and relative humidity. They further show that their model is in good agreement with recent observations of ice clouds.

global change research
Duke Study Shows Carbon Dioxide Boosts Pine Tree Reproduction
Young loblolly pines growing in carbon dioxide-enriched air expected to become the norm later this century are becoming reproductively mature earlier and producing more cones and seeds than identical pines growing in today's air, studies in a Duke University research forest show. While the long term-effects of such changes are still uncertain, "the implications for regeneration are substantial," said Shannon LaDeau, a Duke University doctoral student in ecology who prepared to describe the study recently at the Ecological Society of America's annual meeting in Snowbird, Utah. Economically, loblollies are important, LaDeau said in an interview reported in a Duke University press release. "They are the most important forest product in the Southeast. They tend to be one of the first tree species that will recolonize a disturbed site or an abandoned agricultural site." Studies are under way in three 90-foot-diameter circular plots where entire forest ecosystems, including the 19-year-old loblollies, are being bathed in 1 1/2 times today's levels of atmospheric carbon dioxide. The extra gas is being delivered to each plot by rings of computer controlled towers at the U.S. Department of Energy-funded Forest-Atmosphere Carbon Transfer and Storage experiment (FACTS-1) in Duke Forest. The FACTS-1 site is intended to evaluate how forests will respond to a higher CO₂ atmosphere expected by mid-21st century from fossil fuel combustion and other human activities. Scientists are comparing responses in the carbon dioxide-enriched plots to results in three other matching plots where tower rings are delivering no gas.

global change research
Pacific Decadal Oscillation Packs a One-Two Punch
NASA oceanographer finds evidence of a second PDO cycle lasting about 70 years
The Pacific Ocean, the largest and deepest of the world's oceans, suffers periodic mood swings that have a dramatic impact on our weather. These mood swings include a climate phenomenon known as Pacific Decadal Oscillation, or PDO. It's an El Niño-like shift in the ocean's temperature that scientists once thought cycled every 15 to 20 years. However, there's new NASA research that now shows there may be a second, much longer, PDO cycle that lasts about 70 years. According to a NASA press release, Dr. Yi Chao, an oceanographer at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and colleagues Drs. Michael Ghil and James McWilliams of the University of California, Los Angeles, have found evidence of the PDO's two-part structure in a study of the past 92-year record of sea-surface temperatures in the North and South Pacific. The results of their study appears in the August 1, 2000, issue of Geophysical Research Letters. In addition to the regular large-scale temperature oscillations taking place in the Pacific Basin every 15 to 20 years, Chao and his colleagues also found evidence of another temperature shift that appears to take place on a much longer time scale, about 70 years.

More information about the Pacific Decadal Oscillation is available at NASA's PDO Webpage and the University of Washington's PDO Webpage.

global change research
NASA Scientists Detect Rapid Thinning of Greenland's Coastal Ice
Scientists who want to monitor the state of our global climate may have to look no farther than the coastal ice that surrounds the Earth's largest island. A NASA study of Greenland's ice sheet reveals that it is rapidly thinning, according to a recent NASA press release. In an article published in the 21 July issue of Science, Bill Krabill, project scientist at the NASA Goddard Space Flight Center's Wallops Flight Facility, Wallops Island, VA, reports that the frozen area around Greenland is thinning, in some places, at a rate of more than three feet per year. Any change is important since a smaller ice sheet could result in higher sea levels. "A conservative estimate, based on our data, indicates a net loss of approximately 51 cubic kilometers of ice per year from the entire ice sheet, sufficient to raise global sea level by 0.005 inches per year, or approximately seven percent of the observed rise," Krabill said. "This amount of sea level rise does not threaten coastal regions, but these results provide evidence that the margins of the ice sheet are in a process of change," Krabill said. "The thinning cannot be accounted for by increased melting alone. It appears that ice must be flowing more quickly into the sea through glaciers."

The entire article is available on-line for subscribers to Science Online.

For the past five years, Drew Rothrock, Principal Research Scientist at the University of Washington's Applied Physics Laboratory, has been studying measurements of sea ice draft (sea ice thickness below the water surface) in the Arctic Ocean. Rothrock and colleagues compared sea ice draft data collected on U.S. Navy submarine cruises between 1993 and 1997 with data collected on cruises in the same region between 1958 and 1976. Since changes in sea ice correspond to climate change patterns, Rothrock said he had expected to find that the ice had thinned by maybe 45 to 50 centimeters (18 to 20 inches), but he found that mean ice draft at the end of the melt season in most of the deep-water portion of the Arctic Ocean had actually decreased by about 1.3 meters (3.5 feet). Rothrock's quest to understand the relationship between sea ice and climate change is featured on NASA's Earth Observatory.

global change news

On June 28, the National Oceanic and Atmospheric Administration unveiled the first of a new generation of climate observing stations at the North Carolina Arboretum, in Asheville, N.C. says a NOAA press release. The unveiling took place during the World Botanic Gardens Congress, a major gathering of international plant conservation and horticultural experts. The climate station is the first in a network of automated climate stations called the U.S. Climate Reference Network. The network will potentially consist of 500 climate stations around the country designed for climate monitoring and for placing current climate anomalies into historical perspective. The stations will monitor temperature, precipitation, solar radiation, and wind speed. Hourly observations of these variables will be transmitted in near-real time, and the data and information from the station will be distributed by NOAA's National Climatic Data Center in Asheville.

Tom Karl, director of the climate center, noted, "In 1999 the U.S. National Academy of Sciences asked whether the nation was making measurements, collecting data, and making it available in a way that would enable scientists to increase our understanding of natural and human-induced climate change. Our response was that improvements were needed, and we recommended the development of the Climate Reference Network. This network will provide the United States with a reference network that meets the requirements of the Global Climate Observing System."

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