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By NASA
4 min read
NASA Satellites Reveal Abrupt Drop in Global Freshwater Levels
Earth (ESD) Earth Home Explore Climate Change Science in Action Multimedia Data For Researchers GRACE satellites measure gravity as they orbit the planet to reveal shifting levels of water on the Earth (artist’s concept). NASA/JPL-Caltech An international team of scientists using observations from NASA-German satellites found evidence that Earth’s total amount of freshwater dropped abruptly starting in May 2014 and has remained low ever since. Reporting in Surveys in Geophysics, the researchers suggested the shift could indicate Earth’s continents have entered a persistently drier phase.
From 2015 through 2023, satellite measurements showed that the average amount of freshwater stored on land — that includes liquid surface water like lakes and rivers, plus water in aquifers underground — was 290 cubic miles (1,200 cubic km) lower than the average levels from 2002 through 2014, said Matthew Rodell, one of the study authors and a hydrologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “That’s two and a half times the volume of Lake Erie lost.”
During times of drought, along with the modern expansion of irrigated agriculture, farms and cities must rely more heavily on groundwater, which can lead to a cycle of declining underground water supplies: freshwater supplies become depleted, rain and snow fail to replenish them, and more groundwater is pumped. The reduction in available water puts a strain on farmers and communities, potentially leading to famine, conflicts, poverty, and an increased risk of disease when people turn to contaminated water sources, according to a UN report on water stress published in 2024.
The team of researchers identified this abrupt, global decrease in freshwater using observations from the Gravity Recovery and Climate Experiment (GRACE) satellites, operated by the German Aerospace Center, German Research Centre for Geosciences, and NASA. GRACE satellites measure fluctuations in Earth’s gravity on monthly scales that reveal changes in the mass of water on and under the ground. The original GRACE satellites flew from March 2002 to October 2017. The successor GRACE–Follow On (GRACE–FO) satellites launched in May 2018.
This map shows the years that terrestrial water storage hit a 22-year minimum (i.e., the land was driest) at each location, based on data from the GRACE and GRACE/FO satellites. A significantly large portion of the global land surface reached this minimum in the nine years since 2015, which happen to be the nine warmest years in the modern temperature record. Image by NASA Earth Observatory/Wanmei Liang with data courtesy of Mary Michael O’Neill The decline in global freshwater reported in the study began with a massive drought in northern and central Brazil, and was followed shortly by a series of major droughts in Australasia, South America, North America, Europe, and Africa. Warmer ocean temperatures in the tropical Pacific from late 2014 into 2016, culminating in one of the most significant El Niño events since 1950, led to shifts in atmospheric jet streams that altered weather and rainfall patterns around the world. However, even after El Niño subsided, global freshwater failed to rebound. In fact, Rodell and team report that 13 of the world’s 30 most intense droughts observed by GRACE occurred since January 2015. Rodell and colleagues suspect that global warming might be contributing to the enduring freshwater depletion.
Global warming leads the atmosphere to hold more water vapor, which results in more extreme precipitation, said NASA Goddard meteorologist Michael Bosilovich. While total annual rain and snowfall levels may not change dramatically, long periods between intense precipitation events allow the soil to dry and become more compact. That decreases the amount of water the ground can absorb when it does rain.
“The problem when you have extreme precipitation,” Bosilovich said, “is the water ends up running off,” instead of soaking in and replenishing groundwater stores. Globally, freshwater levels have stayed consistently low since the 2014-2016 El Niño, while more water remains trapped in the atmosphere as water vapor. “Warming temperatures increase both the evaporation of water from the surface to the atmosphere, and the water-holding capacity of the atmosphere, increasing the frequency and intensity of drought conditions,” he noted.
While there are reasons to suspect that the abrupt drop in freshwater is largely due to global warming, it can be difficult to definitively link the two, said Susanna Werth, a hydrologist and remote sensing scientist at Virginia Tech, who was not affiliated with the study. “There are uncertainties in climate predictions,” Werth said. “Measurements and models always come with errors.”
It remains to be seen whether global freshwater will rebound to pre-2015 values, hold steady, or resume its decline. Considering that the nine warmest years in the modern temperature record coincided with the abrupt freshwater decline, Rodell said, “We don’t think this is a coincidence, and it could be a harbinger of what’s to come.”
By James R. Riordon
NASA’s Earth Science News Team
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Last Updated Nov 15, 2024 Editor James Riordon Contact James Riordon james.r.riordon@nasa.gov Location NASA Goddard Space Flight Center Related Terms
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4 min read NASA Satellites Find Snow Didn’t Offset Southwest US Groundwater Loss
Record snowfall in recent years has not been enough to offset long-term drying conditions and…
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How Earth’s Surface and Interior are Connected to Freshwater Availability
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By USH
Over the years, numerous mysterious events have been witnessed in the sky, defying explanation. Recently, yet another unusual sky phenomenon was observed over Southern Australia capturing attention and sparking curiosity.
Video footage reveals what appears to be a dome-shaped structure, with an even stranger detail: lightning seems to bounce off or perhaps even originate from within the dome.
The mysterious formation has led to numerous theories. Some viewers suggest it could be a unique (red) rainbow or a rare weather event like a haboob (sandstorm). Others speculate it might be the result of weather manipulation or even an energy field projected over the region.
Opinions also vary on the lightning, some say it’s bouncing off the dome, while others believe it could be emanating from within. Although it may just be an unusual natural phenomenon, the seemly strange interaction with the lightning remains unexplained.
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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The Permafrost Tunnel north of Fairbanks, Alaska, was dug in the 1960s and is run by the U.S. Army’s Cold Regions Research and Engineering Laboratory. It is the site of much research into permafrost — ground that stays frozen throughout the year, for multiple years.NASA/Kate Ramsayer Earth’s far northern reaches have locked carbon underground for millennia. New research paints a picture of a landscape in change.
A new study, co-authored by NASA scientists, details where and how greenhouse gases are escaping from the Earth’s vast northern permafrost region as the Arctic warms. The frozen soils encircling the Arctic from Alaska to Canada to Siberia store twice as much carbon as currently resides in the atmosphere — hundreds of billions of tons — and most of it has been buried for centuries.
An international team, led by researchers at Stockholm University, found that from 2000 to 2020, carbon dioxide uptake by the land was largely offset by emissions from it. Overall, they concluded that the region has been a net contributor to global warming in recent decades in large part because of another greenhouse gas, methane, that is shorter-lived but traps significantly more heat per molecule than carbon dioxide.
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Greenhouse gases shroud the globe in this animation showing data from 2021. Carbon dioxide is shown in orange; methane is shown in purple. Methane traps heat 28 times more effectively than carbon dioxide over a 100-year timescale. Wetlands are a significant source of such emissions.NASA’s Scientific Visualization Studio The findings reveal a landscape in flux, said Abhishek Chatterjee, a co-author and scientist at NASA’s Jet Propulsion Laboratory in Southern California. “We know that the permafrost region has captured and stored carbon for tens of thousands of years,” he said. “But what we are finding now is that climate-driven changes are tipping the balance toward permafrost being a net source of greenhouse gas emissions.”
Carbon Stockpile
Permafrost is ground that has been permanently frozen for anywhere from two years to hundreds of thousands of years. A core of it reveals thick layers of icy soils enriched with dead plant and animal matter that can be dated using radiocarbon and other techniques. When permafrost thaws and decomposes, microbes feed on this organic carbon, releasing some of it as greenhouse gases.
Unlocking a fraction of the carbon stored in permafrost could further fuel climate change. Temperatures in the Arctic are already warming two to four times faster than the global average, and scientists are learning how thawing permafrost is shifting the region from being a net sink for greenhouse gases to becoming a net source of warming.
They’ve tracked emissions using ground-based instruments, aircraft, and satellites. One such campaign, NASA’s Arctic-Boreal Vulnerability Experiment (ABoVE), is focused on Alaska and western Canada. Yet locating and measuring emissions across the far northern fringes of Earth remains challenging. One obstacle is the vast scale and diversity of the environment, composed of evergreen forests, sprawling tundra, and waterways.
This map, based on data provided by the National Snow and Ice Data Center, shows the extent of Arctic permafrost. The amount of permafrost underlying the surface ranges from continuous — in the coldest areas — to more isolated and sporadic patches.NASA Earth Observatory Cracks in the Sink
The new study was undertaken as part of the Global Carbon Project’s RECCAP-2 effort, which brings together different science teams, tools, and datasets to assess regional carbon balances every few years. The authors followed the trail of three greenhouse gases — carbon dioxide, methane, and nitrous oxide — across 7 million square miles (18 million square kilometers) of permafrost terrain from 2000 to 2020.
Researchers found the region, especially the forests, took up a fraction more carbon dioxide than it released. This uptake was largely offset by carbon dioxide emitted from lakes and rivers, as well as from fires that burned both forest and tundra.
They also found that the region’s lakes and wetlands were strong sources of methane during those two decades. Their waterlogged soils are low in oxygen while containing large volumes of dead vegetation and animal matter — ripe conditions for hungry microbes. Compared to carbon dioxide, methane can drive significant climate warming in short timescales before breaking down relatively quickly. Methane’s lifespan in the atmosphere is about 10 years, whereas carbon dioxide can last hundreds of years.
The findings suggest the net change in greenhouse gases helped warm the planet over the 20-year period. But over a 100-year period, emissions and absorptions would mostly cancel each other out. In other words, the region teeters from carbon source to weak sink. The authors noted that events such as extreme wildfires and heat waves are major sources of uncertainty when projecting into the future.
Bottom Up, Top Down
The scientists used two main strategies to tally greenhouse gas emissions from the region. “Bottom-up” methods estimate emissions from ground- and air-based measurements and ecosystem models. Top-down methods use atmospheric measurements taken directly from satellite sensors, including those on NASA’s Orbiting Carbon Observatory-2 (OCO-2) and JAXA’s (Japan Aerospace Exploration Agency)Greenhouse Gases Observing Satellite.
Regarding near-term, 20-year, global warming potential, both scientific approaches aligned on the big picture but differed in magnitude: The bottom-up calculations indicated significantly more warming.
“This study is one of the first where we are able to integrate different methods and datasets to put together this very comprehensive greenhouse gas budget into one report,” Chatterjee said. “It reveals a very complex picture.”
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Jane J. Lee / Andrew Wang
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jane.j.lee@jpl.nasa.gov / andrew.wang@jpl.nasa.gov
Written by Sally Younger
2024-147
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Last Updated Oct 29, 2024 Related Terms
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By Space Force
The U.S. Space Force and Canadian Armed Forces have kicked off an Operations and Sustainment Phase which will provide Canada with six years of access to the Space Force’s Mobile User Objective System Satellite System.
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By NASA
4 Min Read Unique NASA Partnerships Spark STEM Learning on Global Scale
NASA astronaut Thomas Marshburn reading “Goodnight Moon” aboard station for Crayola’s “Read Along, Draw Along” Credits: NASA NASA offers a world of experiences and opportunities to engage young explorers around the globe in the excitement of science, technology, engineering, and mathematics (STEM). NASA’s Office of STEM Engagement collaborates with experts throughout the agency, the U.S. government, and a variety of global partners to spark inspiration in Artemis Generation students everywhere.
Partnerships with the agency reach new audiences. Here are some of the ways NASA and its partners are making exciting STEM learning resources and opportunities available globally.
NASA and Minecraft collaborated to bring NASA missions to life. NASA and Crayola partnered on a series of virtual engagements to encourage students and families to participate in science, technology, engineering, art, and mathematics (STEAM) content – for example, the annual Crayola Creativity Week. NASA partnered with LEGO Education on educational resources to introduce STEAM concepts and careers with students, teachers, and families. NASA joined forces with Discovery Education to provide curriculum support resources, videos, and events through their online platform. NASA recently signed an agreement with Arizona State University’s Milo Space Science Institute to create new opportunities for students to engage in STEM workforce development through 12-week academies using NASA data sets, information from NASA subject matter experts as well as information on the agency’s missions and careers. NASA partnered with Code.org on the development of computer science and coding resources for teachers and students. NASA collaborated with LabXchange to develop free online resources for teachers and students on topics such as solar eclipses, Mars, astrobiology, and Artemis missions, with more than 700 resources available to date. Representative LEGO minifigures in front of European Service Module that will power the Orion spacecraft on Artemis II. Four LEGO minifigures will fly on Artemis I as part of the official flight kit, which carries mementos for educational outreach and posterity.
Credit: NASA/Radislav Sinyak There’s More to Explore With NASA
International educators and students can find even more ways to engage with NASA’s missions and content through these resources, available online to all.
For the youngest explorers, NASA Kids Club offers STEM-based games for students ages 3-9. The agency’s Artemis Camp Experience features hands-on activities designed to introduce K-12 students to the systems that will enable NASA astronauts to return to the Moon with Artemis. NASA’s “First Woman” graphic novel series tells the fictional story of Callie Rodriguez, the first woman to explore the Moon. Created for students in grades 5-12, “First Woman” includes graphic novels in English and Spanish along with accompanying videos, activities, and more. Through the agency’s internship opportunities, students gain authentic experience while being part of the agency’s work. Student challenges available internationally include the Human Exploration Rover Challenge, in which student teams create and test human-powered rovers, and the Space Apps Challenge, a hackathon that aims to solve real-world challenges on Earth and in space. NASA’s ASTRO CAMP Community Partners Program shares NASA STEM content and experiences through youth organizations and informal learning institutions such as museums and libraries, including nearly 30 international partner sites. Citizen scientists anywhere can contribute their local observations through the Global Learning and Observations to Benefit the Environment (GLOBE) Observer app, part of the GLOBE program sponsored by NASA, the National Oceanic and Atmospheric Administration, National Science Foundation, and Youth Learning as Citizen Environmental Scientists. Look up! Use the Spot the Station mobile app and website to know when the International Space Station will pass overhead. NASA is much more than astronauts and rocket scientists. The Surprisingly STEM video series highlights unexpected careers with linked hands-on activities. STEM resources for educators and students can be found anytime on NASA’s Learning Resources website. The agency offers video on demand through NASA+ with unique STEM programming, live coverage of NASA missions, and more. Students put their human-powered rover to the test in NASA’s Human Exploration Rover Challenge.
Credit: NASA Get NASA STEM Updates via Email
NASA STEM’s e-newsletters deliver the latest updates to email inboxes around the world. The NASA EXPRESS weekly e-newsletter offers the latest NASA STEM content and opportunities, while the monthly Earthrise e-newsletter offers themed resources to elevate Earth and climate science in the classroom.
Learn more about how NASA’s Office of STEM Engagement is inspiring Artemis Generation explorers at: https://www.nasa.gov/stem
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Last Updated Oct 02, 2024 Related Terms
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