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Published:August 30th, 2007 01:44 EST
Direct observations of atmosphere help scientists measure climate change

Direct observations of atmosphere help scientists measure climate change

By SOP newswire

This is the first in a series about U.S. contributions to direct observations of the changing climate.

Washington -- Once a week, usually on Tuesday, individuals in countries around the world travel to coastlines when the wind is from the sea, hike to mountain heights or walk miles into the desert.

When they are far enough away from local pollution, they fill two glass flasks with air that has crossed expanses of oceans or kilometers of desert, using a battery-operated pump and compressor.

The volunteers are as different as their surroundings: a retired teacher in the Gobi Desert at Ulaan Uul in Mongolia who travels more than 12 hours by train to submit her samples; a soil scientist in Kazakhstan; a charter-boat captain on Christmas Island, Kiribati; staff members from the Algerian meteorology department; a company in Poland that runs a car ferry that crosses the Baltic; and many more.

After several weeks of collections, the volunteers deliver the flasks to a mail room in a U.S. Embassy, a nearby meteorological agency or a university department. From these places -- 60 sites around the world -- the flasks are returned to a laboratory in Boulder, Colorado.

There, at the U.S. National Oceanic and Atmospheric Administration’s (NOAA) Earth Science Research Laboratory (ESRL), scientists in the Global Monitoring Division analyze the air to determine the global mix of greenhouse gases like carbon dioxide (CO2).

“We get about 15,000 [flasks] a year,” said Russell Schnell, director of observatory and global network operations in the Global Monitoring Division, during an August 24 USINFO interview.


The worldwide air-sampling network helps NOAA collect reliable data on the concentrations of greenhouse gases in the atmosphere -- one of the measures that contribute to climate assessment reports produced every five years or so by the United Nations' Intergovernmental Panel on Climate Change (IPCC).

The World Meteorological Organization (WMO) and the U.N. Environment Programme established the IPCC to assess the scientific, technical and socio-economic information needed to understand climate change and its impacts.

The IPCC reports, prepared by hundreds of scientists from around the world, give a comprehensive view of human understanding of climate science and climate change. Major assessments were made in 1990, 1995, 2001 and 2007.

The latest report says the climate system is warming and scientists are more than 90 percent sure that the cause is people and the fossil fuels they burn. This certainty arises from direct observations of air and ocean temperature, rain, ice and snow and greenhouse gas concentrations.

NOAA’s Global Monitoring Division contributes to the IPCC assessments through its network of volunteers, six manned stations that continuously sample air -- four of them since the late 1950s -- volunteer ships that carry NOAA instruments, and a dozen commercial and private planes that carry instruments and measure vertical columns of air.

Division scientists also help other countries -- including the Republic of Korea, Mongolia and China -- set up greenhouse gas monitoring stations.


The NOAA division, along with every meteorological service in every country, is also part of the WMO, which coordinates international measurements.

It also participates in the decades-old U.N. Global Atmosphere Watch, a network of laboratories worldwide that provides data for scientific assessments and early warnings of atmospheric changes that could affect the environment.

“We form an important part of the WMO network,” said ESRL senior scientist Pieter Tans. “Not only do we make a lot of measurements but we play an important role in international quality control because we maintain the calibration scales for CO2, methane and nitrous oxide in air, and a few other gases.”

The Global Monitoring Division sets the world standard for measuring these gases, keeps samples of carefully measured amounts of each reference gas and sends out samples to other labs around the world so these labs can use the reference gases to calibrate their instruments.

All the data the division ever has collected is freely available on the organization’s Web site to anyone who wants to use it, Tans said.


Over the years, what has changed is the greatly increased number of measurements and the platforms for making them.

“We now make many more measurements from tall television and FM radio antennas,” Tans said. “Some of the towers are 2,000 feet [610 meters] tall. We have air intake lines at different heights and we measure 24 hours a day.” Another change is making fairly frequent measurements from small airplanes.

Using these and other monitoring techniques worldwide, Tans said, “we have a pretty good idea of how much CO2 is taken up by ocean basins or how much is released from tropical oceans, as well as from direct human activities.”

Such sensitive measuring abilities will be important in the next few years, he added, when countries begin trying to decrease CO2 emissions as a way to slow climate change.

“We are gearing up to quantify this,” Tans said, “to see how successful the new policies are. We want to build a system that can give objective feedback on actual emissions, which I think will be helpful to policymakers and to the public.”

More information about the ESRL Global Monitoring Division is available at the NOAA Web site.

More information about the World Meteorological Organization and the Global Atmosphere Watch is available on their Web sites.

For more information on U.S. policies, see Climate Change and Clean Energy.

(USINFO is produced by the Bureau of International Information Programs, U.S. Department of State. Web site:

By Cheryl Pellerin
USINFO Staff Writer