June 18, 2014 – University of Utah atmospheric scientist John Lin will visit Vandenberg Air Force Base, Calif., soon to watch NASA launch the first satellite dedicated to measuring the global distribution of climate-warming carbon dioxide gas.
As a member of NASA’s science team for the Orbiting Carbon Observatory-2 or OCO-2, Lin then will get busy analyzing data collected by the robotic spacecraft, focusing on carbon dioxide emissions from Los Angeles and the world’s other “megacities.”
“The current estimate is that cities are responsible for about 70 percent of energy-related carbon dioxide emissions worldwide, so cities are a big contributor,” says Lin, an associate professor of atmospheric sciences at the University of Utah. “More than half of the global population currently resides within cities, and it is anticipated that the urban population will continue to rise over the next several decades.”
Launch of OCO-2 was scheduled at Vandenberg for 3:56 a.m. MDT on Tuesday, July 1, but as with all launches, the time is subject to change. Updates may be followed at http://oco.jpl.nasa.gov and http://www.nasa.gov/oco-2/.
NASA says the OCO-2 mission “will provide a more complete, global picture of the human and natural sources of carbon dioxide, as well as their ‘sinks’ – the natural ocean and land processes by which carbon dioxide is pulled out of Earth’s atmosphere and stored. Carbon dioxide, a critical component of Earth’s carbon cycle, is the leading human-produced greenhouse gas driving changes in Earth’s climate.”
Lin and his research group will combine computer simulations or “models” of the atmosphere with urban carbon dioxide measurements from the OCO-2 satellite to “back calculate” emissions of carbon dioxide or CO2 from urban regions.
From its 438-mile-high, near-polar orbit, “OCO-2 will provide a unique way to measure from space the degree to which carbon dioxide is enhanced over cities around the globe,” he says.
Lin and his colleagues will analyze the OCO-2 measurements and try to isolate carbon dioxide emissions from cities by studying how urban atmospheric levels of the gas are influenced by shifting winds and emissions from nonurban sources such as forest fires and from vegetation and oceans – both of which absorb and emit the gas.
If the approach used in Los Angeles works, “we will look at other large urban areas – megacities – with populations more than 10 million,” Lin says. “There are currently about 30 megacities around the world, such as Mexico City, Sao Paulo, Manila, Tokyo and Seoul. I am sure that there will be numerous researchers looking at other cities around the world using the OCO-2 dataset too.”
Lin and University of Utah biologists Jim Ehleringer, Diane Pataki and Dave Bowling already have been studying ground-based measurements of carbon dioxide in the greater Salt Lake City area (http://co2.utah.edu/). But Lin suspects OCO-2 satellite measurements won’t add much to the Salt Lake City research because the strength of the city’s carbon dioxide “signal” is relatively weak when measured from space.
In addition to monitoring human-caused emissions from different areas of the world, a major goal of the OCO-2 mission is to discover natural “sinks” on land and in the oceans that absorb carbon dioxide gas. Despite sharp increases in emissions due to fossil-fuel burning since the Industrial Revolution, less than half of the carbon dioxide emitted into the atmosphere by human activities stays there. Scientists want to know where it goes so they can better predict future concentrations in the air and make climate change predictions more accurate.
Lin says his urban emissions research using OCO-2 data doesn’t directly relate to that question because “the missing ‘sinks’ are related to the vegetation on the land surface absorbing carbon dioxide from the atmosphere. It’s unknown which parts of the global land surface are absorbing the carbon dioxide and why, but we don’t think the sink is in cities.”
NASA tried to launch its first satellite dedicated to making carbon dioxide measurements in 2009, but OCO-1 instead crashed into the ocean. Lin wasn’t on the NASA science team at the time – he was on the faculty of Canada’s University of Waterloo – “but I was pretty disappointed from a scientific perspective, being a potential user of the OCO-1 data.”
A NASA news release detailing the OCO-2 mission can be found here.
John Lin’s homepage can be found here.