Bloomberg BNA — The National Aeronautics and Space Administration plans to launch July 1 its first satellite dedicated to measuring carbon dioxide levels in Earth's atmosphere.
The $465 million Orbiting Carbon Observatory-2 (OCO-2) mission seeks to provide a more complete picture of human and natural sources of carbon dioxide globally, as well as sinks where carbon dioxide is absorbed.
On average, the Earth's plants and oceans absorb about half of the nearly 40 billion tons of carbon dioxide added to the atmosphere each year from the burning of fossil fuels and other human activities. But while carbon dioxide emissions increase at a steady rate, the amount of carbon dioxide absorbed by surface sinks varies from year to year, Mike Gunson, one of the project's scientists, said.
Gunson said understanding what drives these changes in the fate of carbon dioxide in the atmosphere will help scientists reduce uncertainties in global climate change projections. One of the biggest uncertainties is how much carbon dioxide will be put into the atmosphere , he said.
“What we do in the future, how much oil we consume, how much coal we use, that's a socioeconomic question,” he told Bloomberg BNA after a media briefing June 12. The question NASA hopes to help answer is how Earth reacts to rising carbon dioxide emissions.
“Do we get greening of plants? Do they thrive and take down more [carbon dioxide]?” Gunson said. Or, “if we have drought in the Amazon, how much will that dampen down its ability to take in carbon dioxide?”
“Those are the kinds of things we'd like to get a handle on,” he said.
‘Unprecedented' CO2 Picture Seen
The NASA satellite, which replaces a nearly identical spacecraft lost in a rocket launch failure in 2009, will be launched from the Vandenberg Air Force Base in California.
“The timing for this mission couldn't be more appropriate,” given recent steps to reduce carbon emissions as part of the president's climate action plan, Betsy Edwards, OCO-2 program executive at NASA headquarters, said during the briefing.
Edwards said “the data we provide will help our decision makers at both the local and federal levels to be better equipped to understand carbon dioxide's role in climate change.”
The satellite's instrument will densely sample the globe once every 16 days for at least two years, which she said will provide a global description of carbon dioxide in the atmosphere with an “unprecedented level of coverage and resolution.”
NASA's goal is to measure atmospheric carbon dioxide concentrations with a sensitivity of one part per million.
Measurements, Data to be Combined
The satellite's measurements will probably be combined with data from other sources, including carbon dioxide and methane concentrations being monitored by Japan's Greenhouse Gases Observing Satellite (GOSAT).
NASA's measurements also will be validated against the National Oceanic and Atmospheric Administration's ground-based observation system, which has been measuring carbon dioxide in the atmosphere since the mid-1950s.
Jim Butler, who directs global monitoring at NOAA's Earth System Research Laboratory in Boulder, Colo., said the ground-based observation system is the world's most reliable source of information on trends in global greenhouse emissions.
But NOAA has only about 70 observation sites, and even with World Meteorological Organization (WMO) partners, there are only about 150 sites globally measuring greenhouse gas emissions. “That's not very many when you consider the size of the Earth,” Butler told Bloomberg BNA.
Satellite Will Fill Gaps
“What a satellite can do is start to fill the gaps there” and “begin to target these emissions at a finer, more granular level,” he said. “That could be very useful.”
Still, Butler said satellites can have trouble seeing through clouds or over the ocean.
To help avoid clouds, NASA's satellite will look at one square mile at a time. The satellite also will operate in two modes, one in which the instrument is pointed straight down toward Earth and another in which the instrument is pointed near the sun's reflection on Earth, which would make it easier to get accurate measurements over dark oceans.
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