News Archive
March 2000

The U.S. Department of Energy's AmeriFlux Measurement Network offers half hourly measurements of CO₂, water vapor, and energy exchange determined using the Eddy Covariance Technique from different ecosystems integrated into consistent, quality assured, and fully documented data sets. The AmeriFlux program, a part of the international FLUXNET, provides an infrastructure for guiding, collecting, synthesizing, and disseminating these measurements to help define the current CO₂ budget and to improve predictions of future atmospheric CO₂ concentrations. Finalized data sets are available for a number of AmeriFlux sites including Walker Branch Watershed (Tennessee) for 1995-1998, Shidler (Oklahoma) for 1996-1997, Ponca City (Oklahoma) for 1996-1997, Metolius Natural Research Area (Oregon) for 1996-1997, and Harvard Forest (Massachusetts) for 1992-1995.

data policies
Agency Data Access Policy Statements Now Available
Policy statements regarding access to data obtained from research at three federal agencies--the U.S. Environmental Protection Agency (EPA), the National Aeronautics and Space Administration (NASA), and the U.S. Geological Survey (USGS)--are now available in the Data Policies Forum under the Agency Data Access Policies heading. Data access policies from other federal agencies will be posted soon.

March 22, 2000 -- A large iceberg was "born" early this week from the Ross Ice Shelf in Antarctica near Roosevelt Island according to a press release from the National Science Foundation (NSF). Scientists say the massive iceberg could drift to sea within the next few days. The iceberg has begun peeling away from the main ice sheet only 200 miles east of the NSF's McMurdo Station as measured from the berg's western edge. Among the largest ever observed, the iceberg is approximately 170 miles long × 25 miles wide. Its 4,250 square-mile area is nearly as large as the state of Connecticut. The iceberg was formed from glacial ice moving off the Antarctic continent and calved along pre-existing cracks in the Ross Ice Shelf near Roosevelt Island. The calving of the iceberg essentially moves the northern boundary of the ice shelf about 25 miles to the south, a loss that would normally take the ice shelf as long as 50-100 years to replace.

Up-to-date satellite images are available on the Antarctic Meteorology Research Center (AMRC) Iceberg Page at the University of Wisconsin.

global change research
The Oceanic Tidal Cycle: A Possible Cause of Rapid Climate Change
Research on 1,800-year Ocean Cycles Reveals Rapid Global Warming in Near Future
Scientists at Scripps Institution of Oceanography at the University of California, San Diego, report evidence of pronounced changes in the earth's climate that can be tracked in cycles of ocean conditions over thousands of years. These cycles reveal that Earth is currently in a period in which a natural rise in global temperatures--combined with warming from the greenhouse effect--will push the planet through an era of rapid global warming. Charles Keeling and Timothy Whorf report in the March 21 online edition of the Proceedings of the National Academy of Sciences (PNAS) that strong oceanic tides are the engines behind this warming-cooling cycle that may help determine future climates. This report is the first comprehensive study of the effects of tidal mixing on climate change spanning millennia. The current phase in the cycle suggests that a natural warming trend began a hundred years ago, picked up in the 1970s, and should continue over the next five centuries. "We have discovered an 1,800-year tidal cycle that appears to match with recent climate change," said Charles Keeling in a press release from Scripps. "If this is a correct mechanism for understanding climate change over millennia, then temperatures will rise both because of weaker tidal mixing and because of the greenhouse effect, which is on the increase as well."

This continuously-updated catalog provides a comprehensive list of global change-related data sets made available during 2000 from federal agencies. The fourth in a series of yearly publications, this catalog represents an important step in the interagency process of making data and information from the U.S. Global Change Research Program available to researchers, the commercial world, policy makers, and the public.

The study of clouds, where they occur and their characteristics, play a key role in the understanding of climate change. Low, thick clouds primarily reflect solar radiation and cool the surface of the Earth. High, thin clouds primarily transmit incoming solar radiation; at the same time, they trap some of the outgoing infrared radiation emitted by the Earth and radiate it back downward, thereby warming the surface of the Earth. A new article in the Library section of NASA's Earth Observatory describes such effects of clouds on climate and their mediating role in Earth's energy budget.

news
The Potential Health Impacts of Climate Variability and Change for the United States
U.S. National Assessment Health Sector Releases Executive Summary
Continued improvements in public health and the vigilant monitoring both of climate conditions and of the nation's health status are key to protecting the health of Americans, according to the executive summary of the Report of the Health Sector, conducted as part of the U.S. National Assessment of the Potential Consequences of Climate Variability and Change. The study focused on five categories of health outcomes that are most likely to be affected by climate change because they are associated with weather and/or climate variables: temperature-related morbidity and mortality, health effects of extreme weather events, air-pollution-related health effects, water- and food-borne diseases, and vector and rodent-borne diseases. This summary is published in the April issue of Environmental Health Perspectives and is available on-line as of 15 March 2000. Comments and feedback on this study can be provided to healthfx@jhsph.edu.

global change research
Study Points to U.S. As Generator of Greenhouse Gases
Researchers refute suggestions of excessive carbon sequestration in North America
New research has found that the massive amounts of atmospheric carbon dioxide generated by fossil fuel use in the United States are not completely "offset" by the storage of carbon in growing forests and other vegetation of North America, as some earlier studies had suggested. The new study, recently published in the 17 March 2000 issue of the journal Science, may have important implications for the role of the United States in combating the greenhouse effect and global warming. "Some have argued that the U.S. does not need to reduce greenhouse gas emissions because we're not part of the problem," said Ronald Neilson, a professor of botany at Oregon State University and bioclimatologist with the USDA Forest Service. "Based on this study, we can no longer make that claim."

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

global change research
Predicting Hurricanes
Winds in Pacific climate cycle can foretell Gulf of Mexico hurricanes
A short-term climate cycle that builds in the Indian Ocean and moves eastward through the equatorial Pacific Ocean is a key factor in the formation of hurricanes and tropical storms over the Gulf of Mexico and the western Caribbean Sea, according to University of Washington researchers. The findings relate to westerly winds in the Pacific associated with a cycle called the Madden-Julian Oscillation. Data culled from climate and weather records from 1949 through 1997 show that, about 15 days after detection of those winds in the western Pacific, hurricanes and tropical storms are four times more likely to form in the gulf and in the western Caribbean, the scientists said. The area extends from eastern Texas to about the eastern edge of Cuba. "If you saw a relatively strong wind burst coming across the western Pacific, you could say that within a couple of weeks you might expect hurricane activity in the Gulf of Mexico," said Eric Maloney, a UW atmospheric sciences doctoral student in a UW press release. He and Dennis Hartmann, a UW atmospheric sciences professor, report their findings in the March 17 edition of Science.

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

global change data
Global Soil Moisture Data Bank
The Global Soil Moisture Data Bank at the Department of Environmental Sciences at Rutgers - The State University of New Jersey includes data sets from soil moisture observation stations in Eurasia (including China, India, Mongolia, and the former Soviet Union) as well as the slightly less exotic locales of Iowa and Illinois. These data sets are available by clicking on a map of Eurasia and the two US states. Links to other data sets include those for Australia, Brazil, Europe, Russia and Ukraine, and the US. The site also offers abstracts and full-text papers on soil moisture research. Finally, additional sections lead to carefully selected links for model calculations, related projects, and soil moisture measurements.

news
More Drought Looming If Rains Do Not Return, USGS Warns
Last summer's drought may move westward this summer as streamflows in many parts of the United States continue below normal. At a recent press conference and in a recent U.S. Geological Survey (USGS) news release, USGS Director Charles G. Groat warned that continued below-normal streamflow and low ground-water levels may signal a return of last summer's drought. Based on data from the USGS network of more than 7,000 streamgages nationwide, there are some areas of the country -- particularly east of the Mississippi River -- where streamflows are at record-low flows for this time of year. "This is the time of year where streamflow conditions should be about normal, but in the eastern half of the country, we're anywhere but that." Groat said. "We should be seeing ground-water recharge taking place now and we're not seeing that either."

Real-time streamflow data are available from USGS here.

global change research
Air Pollution Can Prevent Rainfall
Latest research shows suppression of rain and snow by urban and industrial air pollution
In a 10 March paper in Science, Dan Rosenfeld of the Institute of Earth Sciences at The Hebrew University of Jerusalem postulates that urban and industrial air pollution can completely shut off precipitation from clouds that have temperatures at their tops of about -10°C over large areas. According to Rosenfeld, satellite data reveal plumes of reduced cloud particle size and suppressed precipitation originating from major urban areas and from industrial facilities such as power plants. Measurements obtained by the Tropical Rainfall Measuring Mission satellite reveal that both cloud droplet coalescence and ice precipitation formation are inhibited in polluted clouds. In a related paper in the same issue, Owen Toon of the University of Colorado describes the mechanism by which rain may be suppressed by pollution.

The entire articles are available on-line for subscribers to Science Online here and here.

global change research
Global Biodiversity Scenarios for the Year 2100
Using projections of atmospheric carbon dioxide, climate, vegetation, and land use and the known sensitivity of biodiversity to these changes, a collection of researchers have developed scenarios of global biodiversity for the year 2100. In a recent paper in Science, these researchers identified a ranking of the importance of drivers of change, a ranking of the biomes with respect to expected changes, and the major sources of uncertainties. For terrestrial ecosystems, land-use change probably will have the largest effect, followed by climate change, nitrogen deposition, biotic exchange, and elevated carbon dioxide concentration. For freshwater ecosystems, biotic exchange is much more important. Mediterranean climate and grassland ecosystems likely will experience the greatest proportional change in biodiversity because of the substantial influence of all drivers of biodiversity change. Northern temperate ecosystems are estimated to experience the least biodiversity change because major land-use change has already occurred. Plausible changes in biodiversity in other biomes depend on interactions among the causes of biodiversity change. These interactions represent one of the largest uncertainties in projections of future biodiversity change.

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

news
U.S. Has Its Warmest Winter on Record
NOAA reports warmest US winter in 105-year recorded history
In a recent press release, the National Oceanic and Atmospheric Administration (NOAA) reported that the winter of 1999-2000 (December through February) was the warmest on record for the United States, according to statistics calculated by NOAA's scientists working from the world's largest statistical weather database. Working from this and current data, NOAA's seasonal winter temperature forecasts for the past two winters have called for much of the country having above normal temperatures. These were based on the expected impacts of La Niña and longer term warming trends.

global change research
Low Carbon Dioxide Levels in Atmosphere During Glacial Periods May Be Caused by Antarctic Sea Ice
A new study indicates that variations in Antarctic sea ice may have played a significant role in lowering atmospheric carbon dioxide (CO₂) concentrations during the last ice age. This study makes progress towards unraveling the mysteries of the past climate changes, a necessary step for predicting future climate. The study by Britton Stephens, a University of Colorado researcher at the National Oceanic and Atmospheric Administration's Climate Monitoring and Diagnostics Laboratory in Boulder, Colo., (formerly of Scripps), and Ralph Keeling of Scripps Institution of Oceanography at the University of California, San Diego, appears in the March 9 issue of Nature and presents a new theory to explain why low carbon dioxide concentrations in the atmosphere are found during glacial periods. According to ice core records, every hundred thousand years or so, the earth cycles between warm periods and cold glacial periods, with Antarctic temperatures varying by about 20 degrees Fahrenheit. Records also indicate that during the glacial periods there was 30 percent less CO₂ in the atmosphere. This study attempts to solve the mystery of the connection between global atmospheric CO₂ concentrations and Antarctic temperatures, which seem to rise and fall together.

global change research
New Satellite Data to Assess Role Clouds Play in Climate Change
A wealth of information on the physical properties and global distribution of clouds -- soon to be collected by a recently launched satellite called Terra -- could help scientists better predict climate change, says a University of Illinois researcher involved with the project. "Terra is the flagship of NASA's Earth Observing System Program, an international effort to monitor Earth's climate over the next 15 years," said Larry Di Girolamo, a professor of atmospheric sciences. "During the satellite's six-year lifetime, its five instruments will help scientists understand how clouds, aerosols, air pollutants, oceans, vegetation and ice cover interact with each other and impact the climate we live in." Di Girolamo's research focuses on clouds. "From a climate-modeling perspective, clouds contribute the largest uncertainty to climate change," he said. "Clouds may have a warming or cooling effect on the planet, depending on the cloud properties. Because clouds are so variable, their effect on global climate has been difficult to quantify." One of the instruments on Terra is the Multi-angle Imaging Spectro-Radiometer. MISR will be the first instrument to make global, high-resolution, multi-angle, multi-spectral radiometric measurements of Earth from space. The instrument will characterize cloud, aerosol and surface properties in a manner no other satellite has been capable of.

More information about the Terra satellite is available at NASA's Terra Website.

The Earth's ice cover is melting in more places and at higher rates than at any time since record keeping began, according to a report from the Worldwatch Institute in Washington, DC. The publication consists of a compilation of reports from around the world which show that global ice melting accelerated during the 1990s, the warmest decade on record. Scientists suspect that the enhanced melting is among the first observable signs of human-induced global warming, caused by the unprecedented release of carbon dioxide and other greenhouse gases over the past century. Glaciers and other ice features are thought to be particularly sensitive to temperature shifts. Loss of the ice could affect the global climate, raise sea levels, threaten key water supplies, and spark regional flooding which could damage property and endanger lives.

global change research
Record Breaking Temperatures Seen as Evidence of Faster Rate of Global Warming
Researchers at the National Ocean and Atmospheric Administration (NOAA)'s National Climate Data Center (NCDC) have found evidence that the rate of global warming is accelerating and that in the past 25 years it achieved the rate of two degrees Celsius (four degrees Fahrenheit) per century. This rate had previously been predicted for the 21st Century. Writing in the March 1 issue of Geophysical Research Letters, Dr. Thomas R. Karl, Director of NCDC, and colleagues analyze recent temperature data. They focus particularly on the years 1997 and 1998, during which a string of 16 consecutive months saw record high global mean average temperatures. This, Karl notes, was unprecedented since instruments began systematically recording temperature in the 19th Century. During much of 1998, records set just the previous year were broken. Karl and his colleagues conclude that there is only a one-in-20 chance that the string of record high temperatures in 1997-1998 was simply an unusual event, rather than a change point, the start of a new and faster ongoing trend. Since completing the research, the data for 1999 have been compiled. They found that 1999 was the fifth warmest year on record, although as a La Niña year it would normally be cooler. Outside the band between 20 degrees north latitude and 20 degrees south latitude, 1999 was the second warmest year of the 20th Century, just behind 1998, an El Niño year.

news
Colorado State Researcher Hopes Mathematicians Can Help Solve Problems that Water Causes in Mathematical Models of Atmosphere
The problem with mathematical models that attempt to mimic global water circulation is water itself, and a professor of atmospheric science at Colorado State University (CSU) is seeking help with the challenge, according to a CSU press release. Water vapor and clouds play a crucial part in the atmospheric branch of the earth's hydrological cycle, but they also play havoc with attempts to describe that process through computer-based mathematical models. David Randall of Colorado State joined a Feb. 20 symposium at the American Association for the Advancement of Science annual meeting in Washington, D.C., to talk about the problems and to seek solutions. In a presentation from 3-6 p.m. with four other geophysical scientists, Randall presented no new, research-based information to an audience made up primarily of applied mathematicians. Rather, he provided some simple information on water vapor and clouds in the atmosphere and outlined some of the difficulties so-called Global Atmospheric Models have encountered. His remarks, and questions he hoped the audience would raise, may spark a new approach to the modeling difficulties, he said. Randall likened the event to bringing together the great mathematician John von Neumann and popular television weatherman Willard Scot to discuss water vapor, clouds and how to represent them in numerical form.

global change research
Scientists Find Clues to Different Warming Rates in Lower Atmosphere and Surface
Three factors--the thinning of the ozone layer, emissions from the Mt. Pinatubo volcano, and the influx of sulfate aerosols and greenhouse gases into the atmosphere--may help explain why the lowest five miles of the earth's atmosphere has not warmed as quickly as the earth's surface, say a group of scientists in a paper appearing in the February 18 issue of the journal Science. The results follow extensive data analysis and modeling studies by the 13 scientists. The difference in temperature trends at the surface and in the lower troposphere has intensified the climate change debate. Some have pointed to the surface data as more reliable, while others have focused on the satellite measurements. In January the National Research Council (NRC) issued a report from a team of scientists across the spectrum of climate change positions that partly reconciles the differences in data sets and offers some explanation of why the temperature trends would be different. The Santer-Wigley paper, though not published at the time, was fully taken into account in the report, says Kevin Trenberth, head of the National Center for Atmospheric Research (NCAR)'s Climate Analysis Section and a coauthor of the NRC report according to an NCAR press release.

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

global change research
Cloud and Climate Curiosity in China
China's decrease in cloud cover accompanied by increased average nighttime temperatures casts into shadows the generally accepted theory that ties increases in global nighttime temperatures to increased cloud cover. A time series analysis produced by the U.S. Department of Energy's Carbon Dioxide Information Analysis Center (CDIAC) shows a significant decrease in both daytime and nighttime cloud cover in China from 1954 through 1996, with an especially large drop-off beginning in 1978. Raw cloud amount data were provided by the China Meteorological Administration to CDIAC. The study, to be published in Geophysical Research Letters, raises many questions and may prompt additional research into atmospheric circulation patterns over China since the 1950s.

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