News Archive

The Energy Department's Atmospheric Radiation Measurement (ARM) Program now offers CO₂ flux estimates from its Southern Great Plains (SGP) site in Oklahoma. Located on the 60 m tower at the ARM Central Facility (CF), the flux measurement system obtains CO₂ and H₂O densities using an infrared gas analyzer, and wind speed and direction and virtual temperature using a sonic anemometer. From these measurements, half hour to four hour mean flux estimates are calculated at 2, 4, 25, and 60 m above the ground. The concentrations and flux estimates from the continuous monitoring at the SGP site are available at the ARM Archive.

Return to page index...

Government and university scientists will be hanging out at the track this summer--only there aren't any horses and the track is located 30,000 feet above sea level. The 'racetrack' is a pattern that a highly instrumented University of North Dakota Cessna Citation aircraft flew over the central portion of North America to measure greenhouse gas emissions. Researchers measured the concentrations of a variety of gases, such as carbon dioxide and sulfur hexafluoride, over a major portion of North America, from late May through June 2003. The scientists will combine the aircraft data with high-resolution winds to determine the emission rates for major greenhouse gases over the continent during the month of the experiment. The flights included measurements of ozone-depleting gases and other pollutants from the New York City-Washington, D.C. metropolitan corridor, Denver, Boston, and Dallas. There were excursions over the Pacific Ocean from Eureka, Calif., and over the Atlantic from Pease, N.H., to Sable Island, to examine coastal influence of marine air and the mixing processes between maritime and continental air. James Elkins, a researcher at the NOAA Climate Monitoring and Diagnostics Laboratory in Boulder, Colo., and a principal investigator on the project, said before the expedition, "This mission will enable us to map the emissions of both ozone depleting and greenhouse gases across the U.S. and Canada in a way we've never been able to do before." Called COBRA (CO2 Budget and Regional Airborne Study), the experiment relies upon the extensive ground-based data from the NOAA Cooperative Station Networks for carbon cycle and halocarbon trace gases, the Fluxnet Canada research network and the AmeriFlux network of ground stations.

Return to page index...

global change data
Dept. of Energy Releases Carbon Dioxide Estimates for Fossil Fuel Consumption
The U.S. Department of Energy's Carbon Dioxide Information Analysis Center (CDIAC) has released a data set titled "Estimates of Monthly CO₂ Emissions and Associated ¹³C/¹²C Values from Fossil-Fuel Consumption in the U.S.A." Produced by T.J. Blasing, Penn State summer student Christine Broniak, and Gregg Marland, and prepared for online distribution by Sonja Jones, the data are available for the years 1981-2002. These estimates were derived from values of fuel consumed, multiplied by their respective thermal conversion factors, and then multiplied by their respective carbon dioxide emission factors. An annual cycle, peaking during the winter months and reflecting natural gas consumption, and a semi-annual cycle of lesser amplitude, peaking in summer and winter and reflecting coal consumption, comprise the dominant features of the annual pattern. There were relatively constant emissions until 1987, followed by an increase from 1987-1989, a decrease in 1990-1991, and record highs during the late 1990s; emissions have declined somewhat since 2000.

Return to page index...

global change research
New Climate Model Predicts Greater 21st Century Warming
For the first time, scientists have incorporated multiple human and natural factors into a climate projection model. They predict that increased carbon dioxide in the atmosphere, due to changes in the carbon cycle, combined with a decrease in human-produced sulphates, may cause accelerated global warming during the 21st century, as compared with simulations without these feedback effects. Results of the study, completed by Chris D. Jones and colleagues at the Met Office's Hadley Centre for Climate Prediction and Research in Bracknell, United Kingdom, appeared recently in Geophysical Research Letters, published by the American Geophysical Union. Previous studies have indicated that human activities, such as carbon dioxide and sulphate emissions, as well as natural factors, such as changes in solar radiation, emissions from volcanic eruptions and interactions between climate and the carbon cycle, are important mechanisms for causing climate change. No previous climate studies have, however, integrated all of these factors into a single climate experiment. The climate-carbon cycle experiment completed by Jones and his colleagues is the first to take a more comprehensive Earth-systems approach to climate modeling. This "all-forcings experiment," or ALL, incorporates carbon dioxide emissions, non-carbon dioxide greenhouse gases, human-produced sulphate aerosol levels, the reflection of solar radiation associated with sulphate in the atmosphere (the "albedo effect"), atmospheric ozone levels, levels of solar radiation, the effects of volcanic eruptions, and climate-carbon cycle feedbacks.

Return to page index...

global change research
New Look at Satellite Data Supports Global Warming Trend
A new analysis of satellite data collected since the late 1970s from the lowest few miles of the atmosphere indicates a global temperature rise of about one-third of a degree Fahrenheit between 1979 and 1999. The results are at odds with previous analyses that show virtually no warming in the satellite record over the 20-year period. The team behind the study includes scientists Tom Wigley, Gerald Meehl, Caspar Ammann, Julie Arblaster, Thomas Bettge, and Warren Washington, all from the National Center for Atmospheric Research. The lead author is Ben Santer of Lawrence Livermore National Laboratory. "It's undeniable that the agreement with both global climate models and surface data is better for the new analysis than for the old one," says Wigley. Over the past 25 years, a series of instruments aboard 12 U.S. satellites has provided a unique temperature record extending as high as the lower stratosphere. Each sensor intercepts microwaves emitted by various parts of the atmosphere, with the emissions increasing as temperatures rise. These data are used to infer the temperature at key atmospheric layers.

Return to page index...

Previous News Stories...