NASA’s Global Climate Change website gets a lot of user feedback. Aside from typical random Internet trolls and students posing thinly veiled attempts at getting us to write their term papers, one of the most commonly asked questions goes something like this:
“Hey, NASA, are you really sure people are causing climate change? Have you double-checked?” or “Hey, NASA, I have an idea. Maybe climate change is caused by x, y, z and it’s not really caused by humans. You should look into this.”
The short answer to this type of question is “Yes, we’ve double-, triple-, quadruple-checked. It’s science! We check and recheck a gazillion times. We’ve looked into everything you could possibly imagine and more. Before we commit to what we say, we have a strong desire to make sure it’s actually true.”
One example of how careful we have to be is when we’re analyzing the carbon dioxide in Earth’s atmosphere from space.
OCO-2 is the NASA mission designed to be sensitive enough to detect a single part of carbon dioxide per million parts of atmosphere (ppm). The way it works is super complicated. And because carbon dioxide is the most important human contribution to climate change (the biggest issue of our time) and expectations of science results were set very high, we have to be super-duper certain our measurements are correct.
The sensitivity makes it very challenging.
The instruments on OCO-2 not only measure the absolute amount of carbon dioxide at a location, but they also look for very small gradients in the distribution of CO2, the difference in the distribution of carbon dioxide between one location and another as a function of time. For example, “a gradient on and off a city is like 2 parts per million,” explained Mike Gunson, project scientist for the mission. "You see 2 parts per million from any city of modest size on up. You’re looking at the difference between 399.5 and 401.5 parts per million. So you have to be careful. Nobody’s done this over New York City, Mumbai, Beijing or Shanghai, where it could be wildly different.”
Scientists spend their lives working to get reliable data. Science is hard; it’s not a walk in the park. Everything doesn't just land in your lap. Sometimes it’s a miracle to get any data at all. People don’t often talk about the challenges of doing science, but if you could uncover the history of any project, you would probably find loads of problems, issues and challenges that come up.
After most NASA satellite launches, the instruments typically go through a validation phase, a two- or three-month period when engineers and project managers check, double-check and recheck the data coming in from the satellite to assess its quality and make sure it’s absolutely accurate before it’s released to the scientific community. But with OCO-2, “there is no validation phase,” Gunson told me, “because the measurements have such sensitivity. You’re always validating. Constant validation is an integral part of ensuring the integrity of the dataset.”
For OCO-2 to make an observation, the sky has to be clear, without clouds. Too much wind will move the carbon dioxide, so you also need quiet meteorological conditions. Then, before we can make an inference, we must assess the quality of data, which involves exceptionally large computing capacity.” Because there is so much data coming in, you end up using all sorts of analysis techniques, including machine learning, to analyze the quality of the data. OCO-2 launched in July 2014, and since this past September the data have been released to the broader science community to sink their teeth into. This means, Gunson said, “after a year of alligator-wrestling, all of a sudden we can walk it on a leash.”
Learn more about NASA’s efforts to better understand the carbon and climate challenge.
I look forward to your comments.
Those of you who follow this blog know that, on top of launching satellites into space, NASA has a suite of Earth-observing instruments, a robust airborne program of instruments mounted on planes, and science ships.
Final frontier? I don't think so. Our catch phrase should be more like "Frontiers are us." We're all over the place.
Recently, Chris Mertens, a NASA scientist interested in galactic cosmic rays, shepherded a NASA balloon all the way to the top of Earth's atmosphere. The balloon, which stood a couple hundred feet tall and held 11 million cubic feet of helium, had a flight train attached to it with a payload of four science instruments and a parachute. He watched it lift off from NASA's Columbia Scientific Balloon Facility in Fort Sumner, New Mexico, and float away on a 24-hour research journey. "It was pretty surreal seeing it drift vertically away," he told me. "The apparatus looked big in the flight facility but looked so small as it was going up. It floated so gracefully, effortlessly."
Up, up and away
As the balloon lifted off, chief engineer Amanda Cutright could hear two sets of cheers, one at the location and a second over the delay at NASA's Langley Research Center where members of the team were watching a broadcast of the event. But she was "still holding her breath," waiting for the data to come in.
Mertens and Cutright, along with project manager Kevin Daugherty and the rest of the Radiation Dosimetry Experiment (RaD-X) team, had spent the past few weeks prepping the balloon and payload in the deserts of New Mexico and had been anxiously awaiting its launch. (Dosimetry is the science of determining radiation dosages received by the human body.) Daugherty told me they'd been waiting for the winds to stagnate in the upper atmosphere so they could fly over the southeastern U.S. for 24 hours without going into the populated areas of Mexico or Los Angeles.
Up in the air
The project actually began years ago when Mertens heard a pilot say, "I'm exposed to radiation and I don't know how much." See, someone on a one-way plane trip from Chicago to Germany on a normal day is exposed to approximately one chest X-ray's worth of radiation. Because commercial airline pilots and aircrew fly so frequently, they are actually radiation workers. So, with his background in cosmic radiation and space weather physics, Mertens knew he could develop a model to predict the radiation levels in Earth's upper atmosphere and answer that question. With this balloon flight, the RaD-X team expects to learn more about the amount of radiation flight crews receive on a daily, monthly or yearly basis and throughout their careers.
Up, up, up, up
About two hours after launch, the balloon reached the middle of the stratosphere, about 110-120 thousand feet up, right on the edge of space. That's about three times as high as commercial airplanes normally fly. From on-board cameras, "we could see the curvature of the Earth and watch the clouds recede," said Cutright. The team wanted to look at the incoming galactic cosmic rays and radiation from the sun above the region where the particles interact with the atmosphere and break up into smaller particles. "Earth's radiation environment is complex," Mertens explained. "Our magnetic field has a dynamic response to the solar wind and varies with latitude. At the polar regions, radiation exposure is maximum because the magnetic field lines are vertical. This means that during a solar storm, the incoming charged particles at the polar cap are parallel to the magnetic field lines, so there's no deflection by the magnetic field."
Yes, Earth's magnetic field is seriously rad.
Just past sunset, they purposely let enough helium out of the balloon to lower it to the 70-89 thousand foot range and have it float there overnight. All four dosimetry instruments collected data at both altitudes to feed into NAIRAS, an analytical model that simulates tissue and how radiation impacts it.
For the rest of the flight, the RaD-X team watched visuals from the onboard cameras, gathered near real-time data on their computers and tracked the balloon flight path from the control room.
"At one point late at night," said Cutright, "we were watching the Earth and we could see the moon. We could see a lightning storm over Oklahoma, all the way from the edge of Texas and New Mexico."
After sunrise, the team watched the parachute deploy so the payload could descend safely; from the camera view, they watched the Earth getting bigger and bigger. The payload was cut from the balloon and a large hole ripped on the side of the balloon so it could fall on its own off to the side. The balloon landed in a rancher's field and the Columbia Scientific Balloon Facility out of NASA Wallops recovered it.
Thank you for reading and for your comments.
P.S. 100 low-cost Cubes in Space experiments from 100 classrooms across the country were also on the flight. Some of their experiments included kernels of popcorn to see if they pop at altitude and seeds and electronics to find out how radiation affects them. Now that you know NASA helped students send kernels of popcorn to the edge of space, aren't you dying to find out if they popped or not? I am. I'll try my best to find out and post it here.
In this new series on "Big Fat Planet," we will answer selected questions about Earth's climate submitted by readers. Recently, a reader asked: "Is there still time to reduce climate change, or is it too late?" The following answer is from Dr. Chip Miller, a researcher specializing in remote sensing of carbon dioxide and other greenhouse gases at NASA's Jet Propulsion Laboratory. He is principal investigator of the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) and was deputy principal investigator for NASA's Orbiting Carbon Observatory satellite mission, which was designed to measure atmospheric carbon dioxide from space.
This is a question that has been asked many times and many studies have investigated similar questions: What level of climate change is "acceptable"? What constitutes "dangerous interference" in the climate system?
The short answer is that it's not too late to act, but our past actions may have already locked in certain outcomes and action is needed to avoid more substantial impacts in the future.
In the 1990s and early 2000s it was generally felt that a doubling of carbon dioxide (CO2) in the atmosphere compared to pre-industrial levels -- that is, CO2 concentrations increasing to about 500 parts per million (ppm) - was "acceptable." However, the series of studies from the Intergovernmental Panel on Climate Change (IPCC) has found that as climate models improve, average worldwide surface temperature is projected to increase well beyond the "acceptable" level of 2.0 degrees Celsius (3.6 degrees Fahrenheit) by 2100. (See the IPCC website for the reports and most recent information.)
Jim Hansen (head of NASA's Goddard Institute for Space Studies) has been one of the more outspoken advocates of curtailing CO2 emissions immediately to return atmospheric CO2 levels to about 350 ppm (the level of carbon dioxide that was in the air in the late 1980s). The challenge here is that even if human emissions of CO2 were cut to zero today, there is an inertia in the climate system that would continue for hundreds to thousands of years as the system attempts to re-equilibrate. (See Hansen's Royal Society paper, "Climate change and trace gases," for more details.)
Michael Oppenheimer [Professor of Geosciences and International Affairs at Princeton University] and colleagues have taken a different approach to assessing climate change risk - they define the likelihood of certain environmental outcomes for different levels of atmospheric CO2 accumulation. (See their 2002 Science paper, "Dangerous climate impacts and the Kyoto Protocol," for a look at three potential outcomes at different CO2 levels.)
“Perception of climate change,” J. Hansen, M. Sato & R. Ruedy, Proceedings of the National Academy of Sciences (6 August 2012); doi: 10.1073/pnas.1205276109.
An interesting recent paper from Dr. Son Nghiem at NASA’s Jet Propulsion Laboratory and colleagues finds that the bottom of the Arctic Ocean controls the pattern of sea ice thousands of feet above on the water’s surface. The seafloor topography exerts its control not only locally, in the Bering, Chukchi, Beaufort, Barents and Greenland Seas, but also spanning hundreds to thousands of miles across the Arctic Ocean.
How? The seafloor influences the distribution of cold and warm waters in the Arctic Ocean where sea ice can preferentially grow or melt. Geological features on the ocean bottom also guide how the sea ice moves, along with influence from surface winds.
Interestingly, the study also links the bottom of the Arctic Ocean with cloud patterns up in the sky. The ocean bottom affects sea ice cover, which affects the amount of vapor coming from the surface of the ocean out into the air, which in turn influences cloud cover.
The researchers, who also come from NASA's Goddard Space Flight Center, the Applied Physics Laboratory and the National/Naval Ice Center in the U.S., use sea ice maps taken from space with NASA’s QuickSCAT satellite, as well as measurements from drifting buoys in the Arctic Ocean. They compare the sea ice and seafloor topography patterns to identify the connection between the two.
Since the seafloor does not change significantly over many years, sea ice patterns can form repeatedly and persist around certain underwater geological features. So computer models need to incorporate these features in order to improve their forecasts of how ice cover will change over the short- and long-term. This ‘memory’ of the underwater topography could help refine our predictions of what will happen to ice in the Arctic as the climate changes.
Source: “Seafloor Control on Sea Ice,” S. V. Nghiem, P. Clemente-Colon, I.G. Rigor, D.K. Hall & G. Neumann, Deep Sea Research Part II: Topical Studies in Oceanography, Volumes 77-80, pp 52-61 (2012).
This is a new image of our planet at night, as taken by a new NASA and National Oceanic and Atmospheric Administration (NOAA) satellite orbiting above us. Scientists recently unveiled this global composite image (and the one below), constructed using cloud-free nighttime images. They show the glow of natural and man-made phenomena across the planet in greater detail than ever seen before. City lights can tell us about how humans have spread across the globe.
Many satellites are equipped to look at Earth during the day, when they can observe our planet fully illuminated by the sun. But with a new sensor onboard the NASA-NOAA Suomi National Polar-orbiting Partnership (NPP) satellite launched last year, scientists now can observe Earth's atmosphere and surface during nighttime hours.
For more Earth at night images, see this article.