Earth’s climate is determined by a delicate balance between how much of the Sun’s radiative energy is absorbed in the atmosphere and at the surface and how much thermal infrared radiation Earth emits to space. A positive energy imbalance means the Earth system is gaining energy, causing the planet to heat up. The doubling of the energy imbalance is the topic of a recent study published June 15 in Geophysical Research Letters.
Scientists at NASA and the National Oceanic and Atmospheric Administration compared data from two independent sets of measurements. NASA’s Clouds and the Earth’s Radiant Energy System (CERES) satellite sensors measure how much energy enters and leaves Earth’s system. A global array of ocean floats, called Argo, provide data to enable an accurate estimate of the rate at which the world’s oceans are warming. Since approximately 90 percent of the excess energy from an energy imbalance ends up in the ocean, the overall trends of incoming and outgoing radiation should broadly agree with changes in ocean heat content.
“The two very independent ways of looking at changes in Earth’s energy imbalance are in really, really good agreement, and they’re both showing this very large trend, which gives us a lot of confidence that what we’re seeing is a real phenomenon and not just an instrumental artifact,” said Norman Loeb, lead author for the study and principal investigator for CERES at NASA’s Langley Research Center. “The trends we found were quite alarming in a sense.”
“It’s likely a mix of anthropogenic forcing and internal variability,” said Loeb. “And over this period they’re both causing warming, which leads to a fairly large change in Earth’s energy imbalance. The magnitude of the increase is unprecedented.”
Increases in emissions of greenhouse gases such as carbon dioxide and methane trap heat in the atmosphere, capturing outgoing radiation that would otherwise escape into space. The warming drives other changes, such as the melting of snow and ice, increased water vapor, and cloud changes that can further enhance the warming. Earth’s energy imbalance is the net effect of all these factors.
In order to determine the factors driving the imbalance, the investigators examined changes in clouds, water vapor, trace gases, the output of light from the Sun, Earth’s surface albedo (the amount of light reflected by the surface), atmospheric aerosols, and changes in surface and atmospheric temperature distributions.
The scientists found that the doubling of the energy imbalance is partially the result an increase in greenhouse gases from human activity, also known as anthropogenic forcing. It can also be attributed to increases in water vapor, which traps more outgoing longwave radiation and further contributes to Earth’s energy imbalance. The related decrease in clouds and sea ice also lead to more absorption of solar energy.
The authors also found that a flip of the Pacific Decadal Oscillation (PDO) from a cool phase to a warm phase likely played a major role in the intensification of the energy imbalance. The PDO is a pattern of Pacific climate variability in which a massive wedge of water in the eastern Pacific goes through cool and warm phases. This naturally occurring internal variability in the ocean can have far-reaching effects on weather and climate. An intensely warm PDO phase that began around 2014 and continued until 2020 caused a widespread reduction in cloud coverage over the ocean and a corresponding increase in the absorption of solar radiation.
“The lengthening and highly complementary records from Argo and CERES have allowed us both to pin down Earth’s energy imbalance with increasing accuracy, and to study its variations and trends with increasing insight, as time goes on,” said Gregory Johnson, co-author on the study and physical oceanographer at NOAA’s Pacific Marine Environmental Laboratory. “Observing the magnitude and variations of this energy imbalance are vital to understanding Earth’s changing climate.”
Loeb cautions that the study is only a snapshot relative to long-term climate change, and that it is not possible to predict with any certainty what the coming decades might look like for Earth’s energy budget. The study does conclude, however, that unless the rate of heat uptake subsides, greater changes in climate should be expected.
May 17th, 2021 by Josh Blumenfeld, NASA ESDS Managing Editor
harmony: 1. A pleasing arrangement of parts. 2. An interweaving of different accounts into a single narrative. (Merriam-Webster Online Dictionary)
The Operational Land Imager (OLI) aboard the Landsat 8 satellite and the Multi-Spectral Instrument (MSI) aboard the Sentinel-2A and Sentinel-2B satellites tell two slightly different stories of Earth. OLI fully images the planet’s land surfaces every sixteen days at 30-meter resolution. MSI images Earth with repeat coverage every five days at 10- to 20-meter resolution.
But what if you could combine, or harmonize, these two data stories into a single narrative? With the provisional release of the Harmonized Landsat Sentinel-2 (HLS) dataset, NASA, the U.S. Geological Survey, and the European Space Agency have done just that. By combining OLI and MSI data—processing it to be used together as if it all came from a single instrument on one satellite—scientists have created global land surface products at 30-meter spatial resolution that are refreshed every two to three days.
“Our definition of ‘harmonized’ is that observations should be interchangeable for common [spectral] bands,” says Jeff Masek, the HLS principal investigator and Landsat 9 project scientist. “By harmonizing the datasets and making the corrections so that it appears to the user that the data are coming from a single platform, it makes it easier for a user to put these two datasets together and get that high temporal frequency they need for land monitoring.”
Two provisional surface reflectance HLS products are available through NASA’s Earthdata Search and NASA’s Land Processes Distributed Active Archive Center (LP DAAC): the Landsat 30-meter (L30) product (doi:10.5067/HLS/HLSL30.015) and the Sentinel 30-meter (S30) product (doi:10.5067/HLS/HLSS30.015). HLS imagery also is available through NASA’s Global Imagery Browse Services (GIBS) for interactive exploration using the NASA Worldview data visualization application.
The HLS image-processing algorithm was initially developed by a team at NASA’s Goddard Space Flight Center starting in 2013, with test versions released in 2015, 2016, and 2017. Even though HLS was still in the prototype stage and covered just 28 percent of Earth’s land surface, the team saw immediate and clear value for the scientific community. The project was scaled up from 28 percent to nearly 100 percent of Earth’s land surface (minus Antarctica) in 2019 by NASA’s Interagency Implementation and Advanced Concepts Team (IMPACT) at NASA’s Marshall Space Flight Center.
The HLS dataset is optimized for use in the Amazon Web Services commercial cloud environment; hosting it in the cloud has significant benefits for data users. “We’re really trying to take data analysis to the next level where we’re able to provide this large-scale processing without large-scale computing requirements,” says Brian Freitag, the HLS project manager at IMPACT. “For example, if you want to look at all the HLS data for a particular plot of land at the 30-meter resolution provided by HLS, you can do this using your laptop. Everything is in cloud-optimized GeoTIFF format.”
The harmonious combination of the OLI and MSI stories is opening new avenues of terrestrial research. A principal HLS application area will be agriculture, including studies of vegetation health; crop development, management, and identification; and drought impacts. HLS data also are being used in a new vegetation seasonal cycle dataset available through LP DAAC.
Global, 30-meter coverage every two to three days? The ability to access and work with years of Landsat and Sentinel imagery in the commercial cloud? That’s a harmonious arrangement the scientific community is eager to explore.
Five decades ago, NASA and the U.S. Geological Society launched a satellite to monitor Earth’s landmasses. The Apollo era had given us our first look at Earth from space and inspired scientists to regularly collect images of our planet. The first Landsat — originally known as the Earth Resources Technology Satellite (ERTS) — rocketed into space in 1972. Today we are preparing to launch the ninth satellite in the series.
Each Landsat has improved our view of Earth, while providing a continuous record of how our home has evolved. We decided to examine the legacy of the Landsat program in a four-part series of videos narrated by actor Marc Evan Jackson (who played a Landsat scientist in the movie Kong: Skull Island). The series moves from the birth of the program to preparations for launching Landsat 9 and even into the future of these satellites.
Episode 1: Getting Off the Ground
The soon-to-be-launched Landsat 9 is the intellectual and technical successor to eight generations of Landsat missions. Episode 1 answers the “why?” questions. Why did space exploration between 1962 and 1972 lead to such a mission? Why did the leadership of several U.S. government agencies commit to it? Why did scientists come to see satellites as important to advancing earth science? In this episode, we are introduced to William Pecora and Stewart Udall, two men who propelled the project forward, as well as Virginia Norwood, who breathed life into new technology.
Episode 2: Designing for the Future
The early Landsat satellites carried a sensor that could “see” visible light, plus a little bit of near-infrared light. Newer Landsats, including the coming Landsat 9 mission, have two sensors: the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS). Together they observe in visible, near-infrared, shortwave-infrared, and thermal infrared wavelengths. By comparing observations of different wavelengths, scientists can identify algal blooms, storm damage, fire burn scars, the health of plants, and more.
Episode 2 takes us inside the spacecraft, showing how Landsat instruments collect carefully calibrated data. We are introduced to Matt Bromley, who studies water usage in the western United States, as well as Phil Dabney and Melody Djam, who have worked on designing and building Landsat 9. Together, they are making sure that Landsat continues to deliver data to help manage Earth’s precious resources.
Episode 3: More Than Just a Pretty Picture
The Landsat legacy includes five decades of observations, one of the longest continuous Earth data records in existence. The length of that record is crucial for studying change over time, from the growth of cities to the extension of irrigation in the desert, from insect damage to forests to plant regrowth after a volcanic eruption. Since 2008, that data has been free to the public. Anyone can download and use Landsat imagery for everything from scientific papers to crop maps to beautiful art.
Episode 3 explores the efforts of USGS to downlink and archive five decades of Landsat data. We introduce Mike O’Brien, who is on the receiving end of daily satellite downloads, as well as Kristi Kline, who works to make Landsat data available to users. Jeff Masek, the Landsat 9 project scientist at NASA, describes how free access to data has revolutionized what we are learning about our home planet.
Episode 4: Plays Well With Others
For the past 50 years, Landsat satellites have shown us Earth in unprecedented ways, but they haven’t operated in isolation. Landsat works in conjunction with other satellites from NASA, NOAA, and the European Space Agency, as well as private companies. It takes a combination of datasets to get a full picture of what’s happening on the surface of Earth.
In Episode 4, we are introduced to Danielle Rappaport, who combines audio recordings with Landsat data to measure biodiversity in rainforests. Jeff Masek also describes using Landsat and other data to understand depleted groundwater.
February 2nd, 2021 by Brian Campbell, NASA Wallops and GLOBE
Trees connect us scientifically, environmentally, and culturally. We all know that trees are vital to our planet’s health. As trees grow, they absorb carbon from the atmosphere, playing a vital role in Earth’s global carbon cycle and helping to regulate Earth’s carbon budget.
But before you read any further, look around…especially if you are outside. Most of you can look in any direction and see a tree. You might wonder about a few things like: “What type of tree is that?” or “Why is that tree so tall or short?” or “How old is that tree?” or even “Was that tree planted by someone, or did the wind blow a seed to where the tree is now standing?”
Or what if you don’t see any trees? What does that signify about the environment? Did nature make it that way, or did humans? All of these are great questions that can help us understand and connect with the environment.
A few trees on Earth also connect us to the Moon. Have you ever heard of “Moon Trees?”
“Moon Trees” never actually grew on the Moon, but their seeds were taken into lunar orbit 50 years ago this week. The NASA Moon Trees history website explains:
Apollo 14 launched in the late afternoon of January 31, 1971, on what was to be our third trip to the lunar surface. Five days later, Alan Shepard and Edgar Mitchell walked on the Moon while Stuart Roosa, a former U.S. Forest Service smoke jumper, orbited above in the command module. Packed in small containers in Roosa’s personal kit were hundreds of tree seeds, part of a joint NASA/USFS project. Upon return to Earth, the seeds were germinated by the Forest Service. Known as the “Moon Trees,” the resulting seedlings were planted throughout the United States (often as part of the nation’s bicentennial in 1976) and the world. They stand as a tribute to astronaut Roosa and the Apollo program.
Among the Moon Trees that were eventually planted around the United States and the world were sycamores, Loblolly pines, redwoods, sweetgums, and Douglas firs. Though it is unlikely the Moon Tree seeds were changed much by their brief lunar orbit, it is still a wonder that they made it into space and back, and that many of the trees are growing and thriving today.
Perhaps you might see some Moon Trees in person in the next year or two. If you do, consider making tree height observations using the tree tools on the NASA GLOBE Observer app. When completing your observation, let us know in the app.
Have you ever visited and seen a Moon Tree? Tell us about it below.
June 29th, 2020 by Emily Cassidy, NASA Earth Science Data Systems
NASA, the European Space Agency (ESA), and the Japan Aerospace Exploration Agency (JAXA) have joined forces to create the COVID-19 Earth Observation Dashboard. The web platform combines the collective scientific power of the agencies’ Earth-observing satellites to document changes in the environment and society in response to the pandemic.
The dashboard is a user-friendly tool to track changes in air and water quality, climate change, economic activity, and agriculture.
Air quality changes were among the first noticeable impacts of pandemic-related stay-at-home orders, and the resulting reductions in industrial activity, that could be tracked through satellite observations. Reductions in nitrogen dioxide (NO2) levels — primarily related to temporary reductions in the burning of fossil fuels — show up clearly in satellite data.
A preliminary analysis also indicates that planting (farming) activity dropped during the quarantines and lockdowns. For example, the cultivated area of white asparagus in Brandenburg, Germany, has been 20 to 30 percent lower this year, compared to 2019. More information on agricultural productivity changes will be added to the dashboard in the months to come.
Recent water quality changes have been reported in a few locations that typically have intense industry and tourism — activities that have decreased during the pandemic. Data on ship identification, construction activity, and nighttime lights (above) are featured on the dashboard to keep track of some of the economic ramifications of the virus.
Together, ESA, JAXA, and NASA will continue to add new observations to the dashboard in the coming months to see how these indicators change. Learn more in the NASA press release, the video below, or by exploring the dashboard.
To counter the rapid spread of COVID-19 in the winter and spring of 2020, quarantines and social distancing measures were implemented around the world. Air traffic nearly ceased; non-essential businesses were closed; and the number of vehicles on the road fell well below normal.
Remote sensing scientists have started looking at potential changes in the environment due to these changes in human behavior. They are looking for signs of how environmental factors such as humidity, temperature, and ultraviolet radiation might play a role in the behavior of the virus. Some may also look for data related to access to water resources, which can be critical to the spread or prevention of certain diseases.
NASA’s Earth Science Data Systems program has developed a new web-based tool, the COVID-19 Data Pathfinder, which provides links to datasets that can be used to research changing environmental impacts from modified human behavior patterns, the possibility of seasonal trends in virus transmission, and water availability. The COVID-19 Data Pathfinder is also a resource for participants in NASA’s Space Apps COVID-19 Challenge, providing an intuitive means for new users to find and use NASA data.
Every time we run one of these tournaments, we are surprised by what catches the eyes of our readers. It is time to surprise us again. Cast your votes now in round three to pick the best four of the Earthly 8. Voting ends on April 13 at 9 a.m. U.S. Eastern Time. Check out the remaining competitors below.
“Past Winners” Bracket: Ocean Sand, Bahamas (#5) vs. A View of Earth from Saturn (#2)
Fire in the Sky and On the Ground has pulled off two massive upsets. In round 1, it beat #2 seed Night Light Maps Open Up New Applications, 71 to 29 percent. In round 2, Fire beat the sentimental favorite and oldest image in Tournament Earth, All of You on the Good Earth — the original Blue Marble photo (1968) and the inspiration for the first Earth Day (1970). The voters chose the auroral fire over Apollo 8 fame by 57 to 43 percent.
“Ice and Land” Bracket: Where the Dunes End (#8) vs. Retreat of the Columbia Glacier (#6)
Since its launch on the web in April 1999, NASA Earth Observatory has published more than 15,500 image-driven stories about our planet. In celebration of our 20th anniversary — as well as the 50th anniversary of Earth Day — we want you to help us choose our all-time best image.
For now, we need you to help us brainstorm: what images or stories would you nominate as the best in the Earth Observatory collection? Do you go for the most beautiful and iconic view of our home? the most newsworthy? the most scientifically important? the most inspiring?
Search our site and then post the URLs of your favorite Earth images in the comments section below. Please send your ideas by March 17.
In late March 2020, we will include some of your selections in Tournament Earth, a head-to-head contest to vote for the best of the best from our archives. Each week, readers will pick from pairs of images as we narrow down the field from 32 nominees to one champion.
The all-time best Earth Observatory image will be announced on April 29, 2020, the end of our anniversary year.
If you want some inspiration as you begin your search, take a look at the galleries listed below. Or use our search tool (top left) to find your favorite places, images, and events.
November 20th, 2019 by Lia Poteet, NASA Earth Science Division Applied Sciences Program
Camp managers and other officials overseeing Rohingya refugee camps in Bangladesh are now incorporating NASA satellite observations into their decision-making. Information like daily rain totals can help inform how to lay out refugee camps and how to store supplies. The goal is to reduce the risk to refugees from landslides and other natural hazards.
Since August 2017, more than 740,000 Rohingya refugees have fled from Myanmar (Burma) to Bangladesh. Many of them have sought shelter in camps in the hilly countryside, where landslide risks are greatest. When refugee camps were built in the southeastern part of the country, many plants and trees were removed — taking with them the roots that could hold the soil in place and help stabilize the landscape when heavy rains come.
Increasing this danger is Bangladesh’s intense monsoon season. Approximately 80 percent of the country’s yearly rain falls from June to October, bringing with it an increased risk of flash flooding and landslides. For instance, July 2019 storms dropped 14 inches of rain in just 72 hours, causing 26 landslides in Rohingya refugee camps around Cox’s Bazar, Bangladesh. One person was killed and more than 4,500 others were left without shelter.
“We have little information on landslides,” said Hafizol Islam, who is in charge of one of the most densely populated camps at Cox’s Bazar. “It is unpredictable for us and can happen at any time.”
Now Islam and other camp managers have access to maps and a website (updated daily) that provides near real-time NASA data on land use, rainfall, and elevation. Data come from the Global Precipitation Measurement (GPM) mission and the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on NASA’s Terra and Aqua satellites, among other sources. Taken together, these maps and data provide a clearer picture of when and where landslide hazards are concentrated.
“With landslides, flash floods, and rapid development, the terrain of these camps is constantly changing,” said Robert Emberson, a postdoctoral fellow at NASA’s Goddard Space Flight Center.
Emberson and other researchers from NASA’s Earth Applied Sciences Disasters Program and Columbia University’s International Research Institute for Climate and Society (IRI) are using new approaches to work alongside humanitarian end-users and develop products to address pressing needs in vulnerable settings. The partnership seeks the feedback of the local people affected and develops maps based on their input.
“We need to understand if, why, and when existing risk information is being used,” said Andrew Kruczkiewicz of IRI, one of the principal investigators of the project. “This strengthens the development of data services for humanitarian emergencies, where decisions and priorities change rapidly. Working in teams that bridge traditional professional and disciplinary boundaries gives data and climate scientists the opportunity to learn more about decision-making in specialized contexts.”
“The partnership with NASA and IRI helps the UN agencies to assess risks like landslides or flash flooding and supports the disaster management in a scientific way to save lives and reduce damages in the refugee camps,” said Cathrine Haarsaker, a project manager for UNDP Disaster Risk Management.
Emberson said seeing the camps in person brought home the importance of connecting with the people on the ground. “Working with satellite data can sometimes feel quite abstract and separate from the people within the images,” he said. “Visiting the camps not only helped us understand more about the specific problems associated with landsliding to help improve our models in the future, but also drove home the human side to this disaster, emphasizing the urgency of our work.”
If you follow science news, this will probably sound familiar.
In May 2019, when atmospheric carbon dioxide reached its yearly peak, it set a record. The May average concentration of the greenhouse gas was 414.7 parts per million (ppm), as observed at NOAA’s Mauna Loa Atmospheric Baseline Observatory in Hawaii. That was the highest seasonal peak in 61 years, and the seventh consecutive year with a steep increase, according to NOAA and the Scripps Institution of Oceanography.
The Mauna Loa Observatory has been measuring carbon dioxide since 1958. The remote location (high on a volcano) and scarce vegetation make it a good place to monitor carbon dioxide because it does not have much interference from local sources of the gas. (There are occasional volcanic emissions, but scientists can easily monitor and filter them out.) Mauna Loa is part of a globally distributed network of air sampling sites that measure how much carbon dioxide is in the atmosphere.
The broad consensus among climate scientists is that increasing concentrations of carbon dioxide in the atmosphere are causing temperatures to warm, sea levels to rise, oceans to grow more acidic, and rainstorms, droughts, floods and fires to become more severe. Here are six less widely known but interesting things to know about carbon dioxide.
The rate of increase is accelerating.
For decades, carbon dioxide concentrations have been increasing every year. In the 1960s, Mauna Loa saw annual increases around 0.8 ppm per year. By the 1980s and 1990s, the growth rate was up to 1.5 ppm year. Now it is above 2 ppm per year. There is “abundant and conclusive evidence” that the acceleration is caused by increased emissions, according to Pieter Tans, senior scientist with NOAA’s Global Monitoring Division.
Scientists have detailed records of atmospheric carbon dioxide that go back 800,000 years.
To understand carbon dioxide variations prior to 1958, scientists rely on ice cores. Researchers have drilled deep into icepack in Antarctica and Greenland and taken samples of ice that are thousands of years old. That old ice contains trapped air bubbles that make it possible for scientists to reconstruct past carbon dioxide levels. The video below, produced by NOAA, illustrates this data set in beautiful detail. Notice how the variations and seasonal “noise” in the observations at short time scales fade away as you look at longer time scales.
CO2 is not evenly distributed.
Satellite observations show carbon dioxide in the air can be somewhat patchy, with high concentrations in some places and lower concentrations in others. For instance, the map below shows carbon dioxide levels for May 2013 in the mid-troposphere, the part of the atmosphere where most weather occurs. At the time there was more carbon dioxide in the northern hemisphere because crops, grasses, and trees hadn’t greened up yet and absorbed some of the gas. The transport and distribution of CO2 throughout the atmosphere is controlled by the jet stream, large weather systems, and other large-scale atmospheric circulations. This patchiness has raised interesting questions about how carbon dioxide is transported from one part of the atmosphere to another—both horizontally and vertically.
Despite the patchiness, there is still lots of mixing.
In this animation from NASA’s Scientific Visualization Studio, big plumes of carbon dioxide stream from cities in North America, Asia, and Europe. They also rise from areas with active crop fires or wildfires. Yet these plumes quickly get mixed as they rise and encounter high-altitude winds. In the visualization, reds and yellows show regions of higher than average CO2, while blues show regions lower than average. The pulsing of the data is caused by the day/night cycle of plant photosynthesis at the ground. This view highlights carbon dioxide emissions from crop fires in South America and Africa. The carbon dioxide can be transported over long distances, but notice how mountains can block the flow of the gas.
Carbon dioxide peaks during the Northern Hemisphere spring.
You’ll notice that there is a distinct sawtooth pattern in charts that show how carbon dioxide is changing over time. There are peaks and dips in carbon dioxide caused by seasonal changes in vegetation. Plants, trees, and crops absorb carbon dioxide, so seasons with more vegetation have lower levels of the gas. Carbon dioxide concentrations typically peak in April and May because decomposing leaves in forests in the Northern Hemisphere (particularly Canada and Russia) have been adding carbon dioxide to the air all winter, while new leaves have not yet sprouted and absorbed much of the gas. In the chart and maps below, the ebb and flow of the carbon cycle is visible by comparing the monthly changes in carbon dioxide with the globe’s net primary productivity, a measure of how much carbon dioxide vegetation consume during photosynthesis minus the amount they release during respiration. Notice that carbon dioxide dips in Northern Hemisphere summer.
It isn’t just about what is happening in the atmosphere.
Most of Earth’s carbon—about 65,500 billion metric tons—is stored in rocks. The rest resides in the ocean, atmosphere, plants, soil, and fossil fuels. Carbon flows between each reservoir in the carbon cycle, which has slow and fast components. Any change in the cycle that shifts carbon out of one reservoir puts more carbon into other reservoirs. Any changes that put more carbon gases into the atmosphere result in warmer air temperatures. That’s why burning fossil fuels or wildfires are not the only factors determining what happens with atmospheric carbon dioxide. Things like the activity of phytoplankton, the health of the world’s forests, and the ways we change the landscapes through farming or building can play critical roles as well. Read more about the carbon cycle here.