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publications
Draft Report Examines Potential Impacts of Climate Change on U.S.
National Assessment Synthesis Team Report Posted for Public Comment
On June 12, the U.S. Global Change Research Program released for public comment a draft report analyzing the potential impacts of global climate change on the United States. The report, to be presented to the President and Congress following final review, was prepared by a team of scientists from government, academia, and the private sector. The report, Climate Change Impacts on the United States: The Potential Consequences of Climate Variability and Change, provides the most detailed look ever at the possible impacts of global warming onthe United States over the next 100 years.

Among its key findings, the draft report indicates that continued growth in worldwide emissions is likely to increase average temperatures across the United States by 5-10 degrees Fahrenheit by 2100; impacts such as heavier precipitation and increased drought will vary widely from region to region; some natural ecosystems are likely to disappear entirely and others may be severely disrupted; changes in rain and snowfall patterns could affect the availability of fresh water; and crop productivity is likely to rise nationally, although regional cropping patterns may change significantly.

publications
U.S. and Russian Federation Release Joint Statement on Cooperation to Combat Global Warming
On June 4, President of the United States Clinton and President of the Russian Federation Putin reaffirmed the commitment of the United States and the Russian Federation to cooperate in taking action to reduce the serious risks of global warming. They take note of the significant contributions to environmental protection made by the U.S.-Russian Joint Commission on Economic and Technical Cooperation under the co-chairmanship of Vice President Gore and the Prime Minister of the Russian Federation. The complete press release is avaiable here on globalchange.gov.

global change research
Ocean Silica May Slow Global Warming
Increasing amounts of silica in the ocean may be removing large quantities of carbon dioxide from the atmosphere, slowing its overall build-up and delaying the onset of global warming. Proposed by Boston College Geologist Kevin G. Harrison, this 'Silica Hypothesis' could explain why atmospheric carbon dioxide levels decreased by 30 percent during glacial periods, a significant change that has perplexed scientists for decades. The hypothesis suggests that changing the supply of silica to the ocean may alter pCO₂ levels. Some of the silica present in the dust dissolves and becomes available for biological uptake. In glacial times, the increased silica levels shifted species composition, changing the distribution of plankton species. Harrison notes that present-day increases in dust level may be removing significant amounts of carbon dioxide from the atmosphere and slowing the rate of global warming.

The entire article, entitled "Role of increased marine silica input on paleo-pCO₂ levels" is published in the June 2000 issue of Paleoceanography (Vol. 15, No. 3, pp. 292-298).

global change research
Global Climate Impacts on a Migratory Songbird
Understanding factors that limit abundances of migratory birds, including climate change, has been difficult because these species move between diverse locations, often on different continents. For black-throated blue warblers (Dendroica caerulescens), demographic rates in both tropical winter quarters and north temperate breeding grounds have been shown to vary with fluctuations in the El Niņo Southern Oscillation, according to a recent paper in the journal Science. According to the authors, adult survival and fecundity were lower in El Niņo years and higher in La Niņa years. Fecundity, in turn, was positively correlated with subsequent recruitment of new individuals into winter and breeding populations. These findings demonstrate that migratory birds can be affected by shifts in global climate patterns and emphasize the need to know how events throughout the annual cycle interact to determine population size.

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

global change data
CDIAC Releases Global Dataset of Total Inorganic Carbon and Total Alkalinity
The Department of Energy's Carbon Dioxide Information Analysis Center recently release a new Numeric Data Package (NDP), Global Distribution of Total Inorganic Carbon and Total Alkalinity Below the Deepest Winter Mixed Layer Depths (ORNL/CDIAC-127, NDP-076). The data package provides monthly gridded (1-degree horizontal by 32 vertical layers) estimates of key ocean CO₂ system values adjusted and interpolated from measurements taken under the World Ocean Circulation Experiment, Joint Global Ocean Flux Study, and Ocean-Atmosphere Carbon Exchange Study. The estimates of total inorganic carbon and total alkalinity are provided only for deep ocean waters, where the absence of large spatial and temporal variability permits the interpolation of the estimates. The estimates of current (mid-1990s) values of ocean carbon parameters are useful for "initializing" models of global carbon cycling, which seek to quantify the role of the oceans in taking up the greenhouse gas carbon dioxide from the atmosphere.

global change news
U.S. Has Its Warmest Spring and Year-to-Date on Record
The spring season (March-May) of 2000 as well as the year-to-date (January-May) was the warmest on record for the United States, according to statistics calculated by National Oceanic and Atmospheric Administration (NOAA) scientists working from the world's largest statistical weather database. The electronic data base at NOAA's National Climatic Data Center in Asheville, N.C., goes back through 106 years of record keeping. According to a NOAA press release, the U.S. national spring season temperatures averaged 55.5°F, 0.4°F warmer than the previous record set in 1910, based on preliminary data. This was 3.3°F warmer than the 1895-1999 long-term mean temperature of 52.2°F. For the three-month period, over 64 percent of the country averaged much warmer than normal while less than one percent averaged much cooler than normal. Global temperatures were also very high during the Northern Hemisphere spring season.

global change research
Antarctic Ice Sheet Unstable in Past Warming Periods
A research team led by University of Florida geologists is the first to find evidence that parts of the Antarctic ice sheet have undergone episodes of massive instability that appear to correspond with periods of unusually warm temperatures in the Northern Hemisphere during the last ice age. The findings, reported in a University of Florida press release and published in the journal Science on June 9, do not address the current debate over global warming and its impact on the polar ice caps. But the research adds to a growing body of evidence suggesting polar ice can undergo huge and rapid changes that may be tied to climate, said Sharon Kanfoush, a UF graduate student and lead researcher on the project. "The fact that the ice sheet has behaved very dynamically in the past, or undergone very rapid changes in the past, implies that such changes are possible in the future," Kanfoush said.

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

A critical aspect of global climate change is the effect of temperature change on carbon storage in the biosphere. For decades, scientists have been examining the atmospheric carbon dioxide record along with global temperature records to find out what happens to excess carbon. In a new article at NASA's Earth Observatory, Dr. David Schimel describes the effect of temperature on atmospheric carbon dioxide concentrations.

A significant decline in ozone over the Arctic last winter was due to an increase in the size and longevity of polar stratospheric clouds, according to a group of researchers who participated in a massive, international atmospheric science campaign reports a University of Colorado press release. The ozone layer that protects life on Earth may not be recovering from the damage it has suffered over the Arctic region as quickly as scientists previously thought, according to a paper published in the May 26 issue of the journal Science. Specifics of the research were presented at the annual meeting of the American Geophysical Union in Washington, DC, on May 31. More polar stratospheric clouds than anticipated are forming high above the North Pole, causing additional ozone loss in the sky over the Arctic, according to Dr. Azadeh Tabazadeh, lead author of the paper and a scientist at NASA's Ames Research Center in California's Silicon Valley. The stratosphere comprises Earth's atmosphere from about 9 to 25 miles (about 15 to 40 kilometers) altitude and includes the ozone layer.

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

global change research
Great Lakes 'Seasons' May Reflect a Warming Trend
Scrutinizing a 139-year record of Great Lakes water levels, a University of Wisconsin-Madison scientist has discovered a dramatic shift in the seasonal changes in water levels on the Great Lakes, according to a university press release. The finding, reported May 24 at a meeting of the International Association of Great Lakes Research by UW-Madison climatologist John D. Lenters, is further evidence that the effects of global warming on natural systems could be far reaching and significant. "The bottom line is that over this 139-year period, the annual rising and falling of Lakes Ontario and Erie has gotten earlier" by about a month, Lenters says describing results of an analysis of long-term trends in Great Lakes water levels. The findings, Lenters says, also show that the range of Lake Ontario's "annual cycle" increased from 17 to 22 inches, a change in volume equivalent to 90 billion cubic feet of water. While Lake Erie does not show the same increase, the one month early arrival of seasonal high and low water levels mirrors that of Lake Ontario. t is likely that the changes observed in the lakes are part of a larger systemic change spurred by increased levels of carbon dioxide in the atmosphere and resulting warming trends, according to the Wisconsin climatologist. Similar long-term shifts in lake ice and river flow in the Great Lakes and Upper Mississippi basins have already been observed by scientists.

global change data
Hourly Precipitation Data on CD-ROM now available from NCDC
A new CD-ROM is now available from the National Climatic Data Center that contains the precipitation observations from the Hourly Precipitation Dataset (HPD) archived at NCDC. The data files have been further quality controlled and rehabilitated for this effort, and contain hourly precipitation amounts for more than 2500 active stations and close to 7000 total stations. The observations on the CD set are available for the period 1948 through June 1998, although some stations have data back to 1900. Access software, available for most UNIX and DOS platforms, is provided to extract the data from the CD-ROM archive, and then can be used to summarize the data into daily or monthly precipitation quantities. Display software, which requires a java-enabled web browser, will generate a zoomable map and time series graphics.

The CD-ROMs may be purchased by clicking here. In addition, all NCDC CD-ROM products are available from the NCDC Climate Products page. If you have further questions, please contact NCDC -- questions@ncdc.noaa.gov, 828-271-4800.

global change research
Increasing Carbon Dioxide Threatens Coral Reefs
According to a press release from the American Geophysical Union, researchers at Columbia University's Biosphere 2 Center have determined that increasing levels of carbon dioxide in the Earth's atmosphere may cause more harm to marine coral reef communities than previous research had indicated. Dr. Christopher Langdon of Columbia's Lamont Doherty Earth Observatory and his research team believe that coral growth could be reduced by as much as 40 percent from pre-industrial levels over the next 65 years. The team found no evidence that reef organisms are able to acclimate after prolonged exposure to the reduced carbonate levels. "This is the first real evidence that increasing atmospheric carbon dioxide levels have a negative impact on a major Earth ecosystem," says Langdon, whose research will be published in the June edition of Global Biogeochemical Cycles, an American Geophysical Union journal that covers global environmental change.

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