Global Climate Monitoring Faces Political and Technical Challenges

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SAN FRANCISCO — In addition to the challenging diplomatic and policy issues that must be resolved, development of a comprehensive, international global climate monitoring system will require technological innovations in satellite sensors, data processing and data management tools, according to government and industry sources.

Government and private investments made during the last 40 years have produced remarkable gains in the ability of researchers to track a broad array of climate-related variables, according to a report released in September by the U.S. Group on Earth Observations (USGEO), which was established by the White House Office of Science and Technology Policy to coordinate U.S. efforts to develop an integrated Earth-observing system. However, a great deal of work remains to be done to ensure that key climate features, including sea level, polar ice and greenhouse gases, can be monitored continuously and indefinitely.

“Gaps in our ability to observe and track these changes will lead to deficiencies in our ability to … project future change and to better craft our near- and long-term response,” said the report, “Achieving and Sustaining Earth Observations: A Preliminary Plan Based on a Strategic Assessment by the U.S. Group on Earth Observations.”

Sensors need to be deployed, for example, to monitor changes in atmospheric carbon levels and to measure the amount of carbon stored in oceans and forests.

“The element of climate change that has received the most discussion in recent years has been the issue of the total carbon budget, including carbon in the atmosphere, oceans and land,” said Ron Birk, former USGEO co-chairman and director of business development for civil systems at Northrop Grumman Aerospace Systems of Redondo Beach, Calif. “The importance of systematically measuring these elements of the carbon budget through deploying technology on orbit, and with distributed surface-based networks, is widely recognized, but not yet realized.”

NASA is scheduled to begin testing one technique for measuring atmospheric carbon in 2013 with the Orbiting Carbon Observatory (OCO), a replacement for the original OCO satellite lost in a launch failure in February 2009. The USGEO report calls on NASA to build a spare OCO instrument, which features three high-resolution spectrometers to measure atmospheric carbon, for possible launch between 2015 and 2017.

While OCO is likely to make a significant contribution to the study of carbon in the atmosphere, the satellite is not designed to offer the type of operational capability that will be needed for long-term global carbon monitoring, U.S. government and industry officials said. Rather, it is an exploratory science mission designed to test one technique for measuring carbon.

“If the nations of the world were to limit the use of fossil fuels, the right to emit carbon dioxide could become an increasingly valuable traded commodity,” said the USGEO report. “In such a world, observations of the location, amount, and rate of carbon dioxide emission into the air, as well as the stock and flow of all forms of carbon on land and in the oceans, will be needed to manage a global carbon market fairly and efficiently.”

To further that technology development, the USGEO report directs NASA to evaluate different laser sounder instruments for measuring atmospheric carbon dioxide as called for in the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission, an Earth Science Decadal Survey mission scheduled for launch between 2013 and 2016. “The laser [carbon dioxide] sounder instruments could complement OCO and provide a great density of measurements through their day and night duty cycle,” said the USGEO report. “NASA may consider additional testing that could include aircraft or other platforms to mitigate risk.”

Another discussion of the emerging technology demands of a comprehensive global climate monitoring capability will be conducted Oct. 21 and 22 during a conference at Draper Laboratory, an independent research and development organization based in Cambridge, Mass. Specifically, that conference will seek to identify the key technical challenges of creating an integrated, operational climate monitoring system, said Phillip Hattis, one of Draper Laboratory’s top technical officials.

“Data sources already deemed essential to tracking key aspects of climate change are at risk of major gaps,” Hattis said.

For example, NASA’s primary mission for monitoring the massive polar ice sheets, the Ice, Cloud and land Elevation Satellite (ICESAT), quit obtaining data in 2009 when the last of its three laser instruments failed. Its successor, ICESAT-2, is scheduled for launch in 2015, leaving a gap lamented by researchers even though NASA is helping to provide ice sheet data in the interim with a series of airborne missions known as IceBridge.

“Data continuity is a big part of the problem,” Hattis said. “When you are trying to track ice accumulation and depletion, and looking for the permanent loss of ice, you can’t miss years.”

Conference attendees also will discuss the challenge of establishing a comprehensive network of ground-based sensors to calibrate airborne and space-based instruments and to verify the data drawn from those instruments. While those sensors are widespread in many parts of the world, “there are vast gaps in Africa, Central Asia and across the oceans,” Hattis said.

Even if those gaps are filled, researchers will need to find a way to maintain the massive amounts of data drawn from numerous sensors in a form that can be accessed by researchers for decades to come and disseminated to anyone who needs it — from government scientists to local officials concerned with the impact on their community of rising sea levels.

“How do you make sure data remains valid and comparable indefinitely?” Hattis asked. “When data is captured by different sensors operating on different platforms, using technology that changes over time, it is not easy to compare.”