Policy commentary

The Value of Climate-Related Satellite Data - Weekly Policy Commentary - February 9, 2009

Feb 9, 2009 | William B Gail

Welcome to the RFF Weekly Policy Commentary, which is meant to provide an easy way to learn about important policy issues related to environmental, natural resource, energy, urban, and public health problems

This week William Gail discusses the role of the National Aeronautics and Space Administration (NASA) in collecting satellite-based data for climate-related purposes. These data play a critical role in monitoring the impacts of climate change, and perhaps giving early warning of possible instabilities in the climate system. The data are also valuable for monitoring emissions-reduction policies, especially in regard to forest carbon sequestration. Oddly, however, little attention is paid to priorities in satellite data collection in current climate legislation.

Earth observations data collected from satellites (which include readings of atmospheric chemistry and temperature, in addition to Earth imagery) play a unique and critical role in supporting policy decisions related to global climate change. Perhaps surprisingly, our process for planning future capabilities of these satellites addresses only a limited aspect of the diverse policy needs society will have when these satellites become operational.

Satellite observations complement climate-related data collected from ground-based monitoring systems. Satellite data improve our ability to monitor and understand how atmospheric accumulations of greenhouse gases (GHGs) change over time, as well as reveal trends in global average and regional temperature. In this way, the data refine the forecast accuracy of scientific models that tell us how atmospheric GHG concentrations will change in response to future GHG sources, what portion of these gases might be absorbed by the oceans and other carbon sinks, and the sensitivity of global temperature to changes in GHG concentrations.

Equally important, the data provide critically needed knowledge about the risk of possible instabilities or “tipping points” in the climate system. Even though the risks might be very small, the potential for globally catastrophic outcomes is among the greatest concerns about warming the planet. One possibility is that higher temperatures could lead to emissions of methane (a potent GHG) from the melting of the permafrost or from beneath the ocean floor, causing substantially greater warming than we currently forecast. Satellite observations of methane concentrations in the atmosphere can help us monitor the mechanisms by which these releases of underground methane might occur, allowing us to anticipate and respond to the problem.

Sea level rise is a widely reported consequence of global warming. A significant portion is expected to come from melting of ice sheets and glaciers. However, the extent to which higher temperatures will lead to melting is poorly understood. Empirical measurement, provided by satellite data, has already proven essential to understanding how ice sheets and glaciers are changing over time. Earth observations data also facilitate the monitoring of many other potential consequences of climate change, such as the expansion of deserts, the disappearance of freshwater sources, harm to sea life through acidification of the oceans as they absorb more carbon, biodiversity loss, and alterations to forests.

satteliteBeyond climate science, satellite data play a potentially critical role in the implementation of policies that address climate change. The trend to include forest carbon and land use within emissions trading programs for reducing GHGs is particularly strong motivation for a robust satellite monitoring program. Satellite data are needed to measure changes in forest cover, and are important, in particular, for monitoring issues such as emissions “leakage” (in which planting of forests in one region is offset by accelerated deforestation elsewhere).

Earth observations even play a role in the establishment of baselines by which to measure emissions reductions programs, as well as assist in evaluating the effectiveness of these programs. In particular, regional emissions of non-carbon dioxide (CO2) GHGs, like methane and nitrous oxides, are easier to track with satellite technologies than ground-based systems. Even space-based measurements of a country’s CO2 emissions are useful as a check on estimates built up from a country’s fuel consumption (which may not be reliably measured for poorer countries with limited accounting systems).

Furthermore, by providing a picture of how resources and natural systems at the local level are impacted by climate change, satellite-based data help to pinpoint where adaptation policies are most needed. Examples include policies to promote the transition to hardier crops in areas at greater risk of drought and construction projects for valuable coastal regions most threatened by sea level rises.

Using Satellite Data to Assist Climate Policy

Earth-based observations of climate-related phenomena are a public good. As there is no private market for this information, its collection must be largely funded by the government. NASA is the only U.S. government entity with a portfolio of satellites capable of generating new scientific understanding of climate issues. Over the last twenty years the United States has invested around $1 billion a year in expanding, maintaining, and operating satellites for climate-related monitoring. The most recent congressional stimulus package (as of this writing, HR1, “The American Recovery Act of 2009”) allocates a further $400 million to fund environmental satellites identified as vital by a 2007 National Academy of Sciences study.

NASA’s data collection over the last two decades has laid the groundwork for understanding how Earth’s complex natural variability—and human influence on it—impacts society. However, the next step is to ensure that this accumulating scientific knowledge is fully applied to improve critical policy and economic decisions. At present there is a fundamental and puzzling disconnect between those parties engaged in crafting domestic climate policy legislation, and those responsible for choosing how to allocate NASA funding among alternative priorities so as to inform policy issues. Legislative proposals provide little detail on how information will be collected and used to monitor emissions control programs, particularly with regard to crediting of forest sequestration and reductions in non-CO2 GHGs. NASA representatives need a more prominent place in deliberations over climate policy design, both to ensure that the best use is made of satellite information and that NASA focuses on the most pressing priorities for earth observation.


Views expressed are those of the author. RFF does not take institutional positions on legislative or policy questions.

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Additional Resources:

Gail, William B. 2007. Sustainable climate policy and NASA. Space News. September 9.

Macauley, Molly K and Daniel F. Morris. 2009. The policy relevance of science. Space News. January 12.

National Research Council. 2007. Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond.

Macauley, Molly K. 2009. Climate Change and Policy Considerations: New Roles for Earth Science. Issue brief 09-02. Washington DC: Resources for the Future.