By Juliet Eilperin
Washington Post Staff Writer
Wednesday, January 12, 2011; A06
A D.C. area company and the Scripps Institution of Oceanography will announce Wednesday that they are launching an ambitious project that aims to precisely gauge how human activity is affecting the climate.
The $25 million, five-year commercial venture will include 50 sensors in the United States and another 50 around the world to measure atmospheric greenhouse gas concentrations.
Most governments and industries estimate their carbon footprint based on an inventory of the fossil fuels they burn, the trees they cut or the landfills they create; this technology will allow experts to quantify how much carbon dioxide and methane has entered the air.
"The ultimate goal for society is to encourage comparisons between what is reported and what is actually in the atmosphere," said Ray Weiss, a distinguished research professor at Scripps who is working on the project. As governments across the United States and the globe adopt measures aimed at curbing greenhouse gas emissions, Weiss added, "it is the only way to know if that policy is really working."
Several government-funded initiatives in the United States and around the world are now seeking this sort of detailed accounting, though many are in the initial stages and are not yet interconnected.
The new initiative comes from Earth Networks, which is headquartered in Germantown and was previously known as AWS Convergence Technologies. It already owns and operates the world's largest weather sensor network, providing data to the federal government and a host of private companies.
To measure greenhouse gases, it will use a "cavity ring-down spectroscopy" instrument developed by Sunnyvale, Calif.-based Picarro, in which light from a laser bounces off mirrors inside the device's chamber. By comparing the speed and behavior of the light in an empty chamber to one containing an air sample - in which carbon would absorb some energy - researchers can determine greenhouse gas concentrations to within a few parts per billion.
The Picarro instruments, which cost $50,000 and are relatively easy to maintain and calibrate, can be deployed more easily than the methods that researchers at the National Oceanic and Atmospheric Administration and elsewhere have used for years. Picarro chief executive Mike Woelk said these advances will allow researchers to measure greenhouse gases "all the way from the global scale to the local scale."
At the moment, NOAA operates one of the world's largest greenhouse gas observation networks, with 70 to 80 stations that collect air samples in flasks that are subjected to infrared analysis.
Robert Marshall, president and chief executive of Earth Networks, said the information the new sensors gather would be particularly valuable in a regulated market in which greenhouse gas emitters can buy and sell carbon credits. While the federal government is unlikely to adopt such a nationwide trading system anytime soon, states such as California and New Mexico are pressing ahead with such policies, as are many nations overseas.
Historically, researchers have focused on measuring the average concentration of carbon dioxide in the atmosphere, a calculation based on data from 40 sites around the world. Many of these monitors are in remote locations. Many of the new networks focus on measuring the atmosphere in more populated regions to better detect the impact of human activity.
Christoph Gerbig, who leads the airborne measurement group at the Max Planck Institute, called Picarro's advances "revolutionary." He added that the instrument can measure low concentrations of carbon dioxide and methane "with a very high degree of accuracy and precision, and make these measurements more routine, with less manpower."
Gerbig helps oversee In-service Aircraft for a Global Observing System (IAGOS), a European Union project that aims to measure greenhouse gas concentrations with equipment attached to commercial jetliners. European scientists hope to launch a 20-year program that will take continuous measurements of such gases as well as other atmospheric chemicals as jets make routine flights.
Back in the United States, the California Air Resources Board is using Picarro instruments on stationary towers in the Los Angeles Basin and the San Joaquin Valley to collect greenhouse gas data. It has four monitors installed and is expanding to other areas in the state.
Richard VanCuren, a research scientist in the board's atmospheric processes section, said rather than collecting information with an eye to enforcing California's climate law, he and other scientists are trying to better understand the seasonal variation of greenhouse gas concentrations and why some areas may have higher emissions than others.
"The goal of the research is to use monitoring to identify hot spots of emissions geographically," VanCuren said.
Jim Butler, who heads NOAA's global monitoring division at its Earth System Research Laboratory in Boulder, Co., said the proliferation of these networks will help give scientists a better sense of how the climate is changing and how to effectively curb global warming.
"We need to know more than the global average [of carbon concentration] is going up," he said, adding that when it comes to measuring greenhouse gases, "We've come a long way, and we have a ways to go."