Model simulation of the hydroxyl radical concentration in the atmosphere. Image by Angharad Stell, University of Bristol.
A mystery about global methane trends just got more muddled. Two studies published in April 2017 suggest that recent increases in atmospheric concentrations of methane may not be caused by increasing emissions. Instead, the culprit may be the reduced availability of highly reactive “detergent” molecules called hydroxyl radicals (OH) that break methane down.
Understanding how globally-averaged methane concentrations have fluctuated in the past few decades—and particularly why they have increased significantly since 2007—has proven puzzling to researchers. As we reported last year:
“If you focus on just the past five decades—when modern scientific tools have been available to detect atmospheric methane—there have been fluctuations in methane levels that are harder to explain. Since 2007, methane has been on the rise, and no one is quite sure why. Some scientists think tropical wetlands have gotten a bit wetter and are releasing more gas. Others point to the natural gas fracking boom in North America and its sometimes leaky infrastructure. Others wonder if changes in agriculture may be playing a role.”
The new studies suggest that such theories may be off the mark. Both of them find that OH levels may have decreased by 7 to 8 percent since the early 2000s. That is enough to make methane concentrations increase by simply leaving the gas to linger in the atmosphere longer than before.
Atmospheric methane has continued to increase, though the rate of the increase has varied considerably over time and puzzled experts. (NASA Earth Observatory image by Joshua Stevens, using data from NOAA. Learn more about the image.)
As a press release from the Jet Propulsion Laboratory (JPL) noted: “Think of the atmosphere like a kitchen sink with the faucet running,” said Christian Frankenberg, an associate professor of environmental science and engineering at Caltech and a JPL researcher. “When the water level inside the sink rises, that can mean that you’ve opened up the faucet more. Or it can mean that the drain is blocking up. You have to look at both.”
Unfortunately, neither of the new studies is definitive. The authors of both papers caution that high degrees of uncertainty remain, and future work is required to reduce those uncertainties. “Basically these studies are opening a new can of worms, and there was no shortage of worms,” Stefan Schwietzke, a NOAA atmospheric scientist, told Science News.
You can find the full studies here and here. The University of Bristol has also published a press release.
Methane emissions related to human activity are on the rise. (NASA Earth Observatory image by Joshua Stevens, using data from CDIAC. Learn more.)
By removing natural and stray light sources, researchers have provided a clearer picture of the human footprint on Earth. Learn more about this image. (NASA Earth Observatory image by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA GSFC.)
NASA’s operating Earth science missions as of March 31, 2017. (Image Credit: NASA’s Earth Observing Project Science Office.)
Some of the environmental challenges we face are daunting and can seem intractable, but there are some good reasons to feel reassured by the tools and expertise that the scientific community brings to the table. Americans live in a country where the number of deaths due to hurricanes, landslides, floods, droughts, tornadoes, blizzards, and other weather hazards have plummeted over the past century, and that is largely due to better understanding and to appropriate hazards warning systems that Earth scientists have developed.
Computers and instruments that used to take up whole rooms now fit snugly onto autonomous aircraft, satellites, and robots. At this moment, 1,459 satellites orbit Earth—including 19 that are part of the NASA fleet keeping a watchful eye on this dynamic, fragile planet. The authors of the EOS article note that a unified, global, high-resolution 3-D map of the human fingerprint on Earth is within reach due to the remarkable lidar instruments, aerial photogrammetry, and satellite observations that are now available.
NASA invites people around the world to help us celebrate Earth Day 2017 by “adopting” one of 64,000 individual pieces of Earth as seen from space. Learn more. (Image Credit: NASA)
To get a sense of the sophistication and breadth of the information satellites now collect, just navigate to your home town with NASA’s Worldview browser or take a look at the Earth Observations (NEO) data archive. You will find information on everything from plant health to particulate aerosol levels to fires to city lights.
As you look, keep in mind that NASA isn’t just collecting that data for data’s sake. The Applied Sciences program is focused on making that data useful to citizens, resource managers, and civic planners in ways that make life better here on Earth. So if you plan to celebrate Earth Day by cleaning up trash in your neighborhood or adopting a piece of the planet with NASA, rest assured that you are not alone in working to make the planet just a little bit more livable.
Bigger isn’t necessarily better—at least where satellites are concerned. Modern “CubeSat” satellites are smaller and more numerous than ever.
The CubeSat takes its name from its dimensions; it is made up of multiples of 10×10×11 centimeter cubic units. A basic CubeSat weighs roughly 3 pounds (1.3 kilograms) and looks a good deal like a portable speaker.
Early satellites started out small, too. Launched in 1957, Sputnik weighed around 184 pounds (83 kilograms). America’s first satellite, Explorer I, weighed just under 31 lbs (14 kg). Then, as the desire for more sensors grew, so did the size of satellites. The first American weather satellite, TIROS I, was a hefty 270 lbs (122 kg). But recent years have seen a reversal of this trend.
Like modern cell phones, satellites have benefited from more compact and more powerful computing technology. (A 1980s cell phone was an expensive, brick-sized gadget that could only place phone calls and store a couple dozen numbers.) Satellites, too, have sprouted new cameras and sensors. Take the IPEX CubeSat developed by NASA’s Jet Propulsion Laboratory (45 seconds into the video below); it can track features like forest fires, volcanic eruptions, and algae blooms.
THE UPSIDES OF BEING SMALL
A satellite today can be a “hitchhiker,” aboard a larger mission, as the video below mentions. Or, a CubeSat can be launched from the International Space Station.
Because they are smaller, CubeSats tend to cost less, so research organizations can deploy more of them. That means more spatial coverage for monitoring the Earth. Where researchers once relied on two or three larger satellites to keep an eye on weather over the Pacific Ocean, now, handfuls of smaller satellites can help with the job.
By measuring Earth’s gravity field, the satellites have pioneered a whole new way of monitoring water. The details of what this pair has observed has been eye-opening. Among the most sobering of GRACE’s many discoveries:
In cat years, Tom and Jerry are nearing 75. To celebrate their longevity, give a read of this excellent overview story written by Holli Riebeek of the Earth Observatory and this list of all the GRACE press announcements from the Jet Propulsion Laboratory. Below are a few of my favorite videos and data visualizations about the mission.
The American Museum of Natural History video offers a quick overview. The State Department video is longer and wonkier, but has some really interesting details. And the 60 Minutes clip (part of this longer episode) is a reminder that NASA studies earth science in a way that few other organizations can. Click on each of the maps below to find out more about them.
Basins shown in shades of brown have had more water extracted than could be naturally replenished.
NASA Earth Observatory images by Joshua Stevens using GRACE global groundwater data courtesy of Jay Famiglietti NASA JPL/University of California Irvine and Richey et al. (2015).
The freshwater storage rate in the United States changed between 2003-2012. Red areas stored less groundwater during that period.
NASA Earth Observatory image by Jesse Allen, using GRACE data provide courtesy of Jay Famigleitti, University of California Irvine and Matthew Rodell, NASA GSFC, and Famiglietti & Rodell (2013).
Water masses move around the planet throughout the year. Blues indicate increases above the normal water storage for an area. Browns indicate decreases.
If you’re like me, you’ll find yourself transfixed by this newly released clip of lightning flashes flitting across Texas skies at night. These data were captured by the Geostationary Lightning Mapper (GLM), a first-of-its-kind sensor that was launched into space on GOES-16 (called GOES-R prior to launch) in November 2016. The sensor makes continuous observations of lightning flashes—a new capability that should markedly improve weather forecasts of severe thunderstorms and tornadoes.
The video clip—an animation of GLM observations overlaid on Advanced Baseline Imager (ABI) cloud imagery—shows lightning flashing over southeast Texas on the morning of February 14, 2017. As explained by NOAA’s Michelle Smith, the green cross indicates the location of Houston, and the green dotted lines show the Texas coastline. Rendered at 25 frames per second, the animation simulates what your eye might see if it was above the clouds. GLM observes the scene at 500 frames per second, and can distinguish the location, intensity, and horizontal propagation of individual strokes within each lightning flash.
At the time of his death on December 23, 2016, Piers Sellers was the deputy director of the Sciences and Exploration Directorate and the acting director of the Earth science division at NASA’s Goddard Space Flight Center. But he was a lot more than that to his colleagues and to the world. NASA science writer Patrick Lynch (and occasional Earth Observatory contributor) had the unenviable task of trying to capture the essence of Sellers:
“As an astronaut, he helped build the International Space Station. As a manager, he helped lead hundreds of scientists. And as a public figure he was an inspiration to many for his optimistic take on humanity’s ability to confront Earth’s changing climate. But his most lasting contributions will be in the field where he began his career: science.”
Piers came to NASA Goddard from Britain in 1982 as a research meteorologist and climate scientist. His focus was the interaction between the biosphere — the living, breathing plant-life of Earth — and the atmosphere. He helped develop models and wrote several papers that are still widely cited in the field. But he also had another lifelong dream: to become an astronaut. He applied to the astronaut training program in the 1990s, and worked through rigorous screening and training to go into space. He flew to the International Space Station in 2002, 2006, and 2010, participating in six spacewalks and helping with assembly of the station. Upon retiring from the astronaut corps, he came back to Goddard and resumed his place as a leader in Earth science, while also promoting conversations and collaborations with researchers studying planetary science and hunting for life beyond our solar system.
I did not have the chance to get to know Piers well. He was someone I mostly watched from afar and our interactions were sporadic, though always interesting, dignified, and thoughtful. I came to know him mostly through his words — to the media and to my fellow scientific and communications staff of NASA Goddard — and in the ways he inspired people. The more I read, the more I wish I had been able to spend more time with him.
In January 2016, one year ago this week, he wrote a poignant op-ed in The New York Times. The words were a compelling prelude to his final year with us.
I’m a climate scientist who has just been told I have Stage 4 pancreatic cancer. This diagnosis puts me in an interesting position. I’ve spent much of my professional life thinking about the science of climate change, which is best viewed through a multi-decadal lens. At some level I was sure that, even at my present age of 60, I would live to see the most critical part of the problem, and its possible solutions, play out in my lifetime. Now that my personal horizon has been steeply foreshortened, I was forced to decide how to spend my remaining time. Was continuing to think about climate change worth the bother?
In the summer of 2016, Sellers wrote another compelling piece, this time in The New Yorker. In “Space, Climate Change, and the Real Meaning of Theory,” he took on a very sensitive and fundamental facet of science: the accumulation of evidence and observation that leads to truth. Here is my favorite passage:
When we talk about why the climate has changed, and what the future climate is likely to be, scientists use analyses and predictions that rest heavily on results from computer models, which in turn rest on layers and layers of theory. And there’s the rub—a lot of the confusion about what is known and unknown about the changing climate can be traced to people’s understanding of the role of theory in science.
Fundamentally, a theory in science is not just a whim or an opinion; it is a logical construct of how we think something works, generally agreed upon by scientists and always in agreement with the available observations. A good example is Isaac Newton’s theory of gravitation, which says that every physical object in the universe exerts a gravity force field around itself, with the strength of that field depending on its mass. The theory—one simple equation—does a superb job of explaining our observations of how planets orbit around the sun, and was more than good enough to make the calculations we needed to send spacecraft to the moon and elsewhere. Einstein improved on Newton’s theory when it comes to large-scale astronomical phenomena, but, for everyday engineering use, Newton’s physics works perfectly well, even though it is more than three hundred years old.
…Engineering theory, based on Newton’s work, is so accepted and reliable that we can get it right the first time, almost every time. The theory of aerodynamics is another perfect example: the Boeing 747 jumbo-jet prototype flew the first time it took to the air—that’s confidence for you. So every time you get on a commercial aircraft, you are entrusting your life to a set of equations, albeit supported by a lot of experimental observations. A jetliner is just aluminum wrapped around a theory.
On camera, it is easy to pick up the energy, humor, and dignity of the man. In the past year, he was a frequent interview subject for the television and radio media. He also made an appearance in Leonardo DiCaprio’s documentary Before the Flood. Some of us think Piers stole the show.
But I am most fond of this simple video, posted last month to YouTube. It’s a conversation between Piers and Compton Tucker, one of his best friends, his next-door neighbor, and a fellow NASA scientist. So many people have stilted and distant impressions about scientists, and Hollywood caricatures don’t help. I like this video because it shows bright people having fun, being human, and savoring life, learning, and friendship.
At the conclusion of his January 2016 piece in The New York Times, Piers offers a thought that inspires us to keep up the good work.
As for me, I’ve no complaints. I’m very grateful for the experiences I’ve had on this planet. As an astronaut I spacewalked 220 miles above the Earth. Floating alongside the International Space Station, I watched hurricanes cartwheel across oceans, the Amazon snake its way to the sea through a brilliant green carpet of forest, and gigantic nighttime thunderstorms flash and flare for hundreds of miles along the Equator. From this God’s-eye-view, I saw how fragile and infinitely precious the Earth is. I’m hopeful for its future.
September 2016 was the warmest September in 136 years of modern record-keeping, according to a monthly analysis of global temperatures by scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York.
September 2016’s temperature was a razor-thin 0.004 degrees Celsius warmer than the previous warmest September in 2014. The margin is so narrow those two months are in a statistical tie. Last month was 0.91 degrees Celsius warmer than the mean September temperature from 1951-1980.
The record-warm September means 11 of the past 12 consecutive months dating back to October 2015 have set new monthly high-temperature records. Updates to the input data have meant that June 2016, previously reported to have been the warmest June on record, is, in GISS’s updated analysis, the third warmest June behind 2015 and 1998 after receiving additional temperature readings from Antarctica. The late reports lowered the June 2016 anomaly by 0.05 degrees Celsius to 0.75.
“Monthly rankings are sensitive to updates in the record, and our latest update to mid-winter readings from the South Pole has changed the ranking for June,” said GISS director Gavin Schmidt. “We continue to stress that while monthly rankings are newsworthy, they are not nearly as important as long-term trends.”
The monthly analysis by the GISS team is assembled from publicly available data acquired by about 6,300 meteorological stations around the world, ship- and buoy-based instruments measuring sea surface temperature, and Antarctic research stations. The modern global temperature record begins around 1880 because previous observations didn’t cover enough of the planet. Monthly analyses are updated when additional data become available, and the results are subject to change.
August 2016 was the warmest August in 136 years of modern record-keeping, according to a monthly analysis of global temperatures by scientists at NASA’s Goddard Institute for Space Studies (GISS).
Although the seasonal temperature cycle typically peaks in July, August 2016 wound up tied with July 2016 for the warmest month ever recorded. August 2016’s temperature was 0.16 degrees Celsius warmer than the previous warmest August (2014). The month also was 0.98 degrees Celsius warmer than the mean August temperature from 1951-1980.
“Monthly rankings, which vary by only a few hundredths of a degree, are inherently fragile,” said GISS Director Gavin Schmidt. “We stress that the long-term trends are the most important for understanding the ongoing changes that are affecting our planet.” Those long-term trends are apparent in the plot of temperature anomalies above.
The record warm August continued a streak of 11 consecutive months (dating to October 2015) that have set new monthly temperature records. The analysis by the GISS team is assembled from publicly available data acquired by about 6,300 meteorological stations around the world, ship- and buoy-based instruments measuring sea surface temperature, and Antarctic research stations. The modern global temperature record begins around 1880 because previous observations didn’t cover enough of the planet.
Many of the Olympic festivities are taking place in Barra da Tijuca, one of the youngest and most affluent neighborhoods in Rio. Credit: Landsat 8/NASA Earth Observatory.
While gymnasts leap, cyclists pedal, and divers twirl for Olympic gold in Rio de Janeiro, sensors on several NASA Earth Observing satellites are catching glimpses of the city and its surroundings from space. The mix of satellites and sensors in orbit are nearly as varied and diverse as the athletes competing below.
The marathoner among NASA’s fleet would have to be Terra. Despite having a design life of six years, this reliable spacecraft has been in orbit since 2000. The multi-purpose satellite carries five scientific payloads and monitors everything from phytoplankton to forest cover to airborne particles called aerosols.
The swimmers would have to be Aquarius, Aqua, and the Global Precipitation Measurement (GPM). All three satellites, as their names suggest, specialize in studying water. Aquarius focuses on measuring the ocean’s salinity. Aqua, like Terra, is versatile: It studies water vapor, sea ice, snow ice, clouds, and more. GPM is the newest of the trio. Launched in 2014, it makes global maps of precipitation and sets standards for precipitation measurements worldwide.
The synchronized divers of space would have to be the Gravity Recovery and Climate Experiment (GRACE). While divers seem to temporarily defy gravity with their flips and turns, the pair of GRACE satellites actually measures Earth’s gravity from space.
The twin GRACE satellites. Credit: NASA
The archers would be CALIPSO and CloudSat. These two satellites shoot laser pulses (CALIPSO) and radar waves (CloudSat) down toward features in the atmosphere such as clouds and smoke plumes. They measures precisely how long it takes for the light or radio waves to bounce back, making it possible to map the vertical structure of the atmosphere.
The images above and below offer a glimpse of some of the types of imagery and data that NASA-Earth observing satellites collect. The image at the top of the page shows how Olympic Park in Rio appeared to the Operational Land Imager (OLI), a sensor on Landsat 8. The image immediately above shows Rio at night as seen by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite. The instrument can sense light 100,000 times fainter than conventional visible-light sensors, making it extremely sensitive to moonlight and city lights.
The image directly above shows a view of Rio and Guanabara Bay on August 6, 2016, the day after the opening ceremony. The fourth image (below) shows a view of aerosols observed over Rio by the Multi-Angle Imaging Spectrometer (MISR) on August 2, 2016.
Scientists at NASA and officials in the Rio de Janeiro government recently signed an agreement about natural hazards preparedness. The hope is that satellite imagery and data—in conjunction with in situ data from the ground—will help scientists better understand, anticipate, and monitor drought, flooding, and landslides that occur in and around Rio. The collaboration will focus on integrating, visualizing, and sharing relevant data from NASA satellites.
Severe mudslides and landslides affected Rio in 2011. Read more about this image here. Credit: EO-1/NASA Earth Observatory
In a NASA press release, Rio de Janeiro Mayor Eduardo Paes said that his city has historically suffered from massive rainstorms and subsequent floods and landslides, all of which can cause casualties and disrupt the economy. Discussions are underway to address those hazards and to plan future cooperative activities.
The 2015 fire season was the most severe ever observed by NASA Earth Observing System satellites, a new study shows. As we reported in December, 2015 was an intense fire season in Indonesia because the drying effects of El Niño exacerbated seasonal fires lit by growers. Many farmers lost control of fires, which then spread through dried-out peat deposits. Peat fires produce thick, acrid smoke rich with greenhouse gases.
Some of the results from their analysis are shown in the chart below. Note that red lines indicate trends in 2006 (also a severe fire year); blacks lines indicate 2015. The tick marks on the X-axis indicate the month of the year. Comparing the two years, it is clear that 2015 was the more severe fire season. The sensors generally detected higher levels (or longer duration of emissions) of each pollutant in 2015. The peak number of fires observed by MODIS was slightly higher in 2006, but the sensor detected more fires overall in 2015. In both 2006 and 2015, fire activity increased rapidly as rainfall decreased.
To see how the 2015 fires compared to severe fire seasons before the Earth Observing System satellites were in space, Goddard Institute for Space Studies scientist Robert Field looked back at longer-term records of visibility collected at Indonesian airports. The chart below compares visibility in 2015 with 1997 and 1991—two other years that were dry because of El Niño. (Note: Bext stands for extinction coefficient; a higher extinction coefficient means more smoke was in the air. The upper part of the chart shows how much rain fell. In that chart, “CPC pcp” stands for precipitation from the Climate Prediction Center, a NOAA research group.) By that measure, 1997 was a far more severe fire season. In Sumatra, visibility was also lower in 1991, though in Kalimantan. visibility was about the same in 2015 and 1991.
“Without significant reforms in land use and the adoption of early warning triggers tied to precipitation forecasts, these intense fire episodes will reoccur during future droughts, usually associated with El Niño events,” the authors emphasized.
+Read a NASA press release about the study here.
+Read a more detailed story about the 2015 fires here.
In Indonesia, dry weather can mean fire. September 2015 data from the TRMM satellite shows lack of rainfall in the areas where fire broke out. Image by NASA Earth Observatory.