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History of the Extraterrestrial Agenda and the Coming Global Revolution
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By Space Force
SecAF Kendall delivered a speech to USAFA cadets about the qualities necessary for strong leadership and why capable, insightful, moral leaders are more essential than ever in defense of the nation.
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By Space Force
In an era defined by rapid technology advancements and with a worldwide platform saturated with Great Power Competition, the Distributed Mission Operations Center on Kirtland Air Force Base, hosted its Virtual Flag: Coalition exercise, Oct. 21 - Nov. 4.
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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
Earth Goddard Space Flight Center GRACE (Gravity Recovery And Climate Experiment) GRACE-FO (Gravity Recovery and Climate Experiment Follow-on) Water on Earth Explore More
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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5 months ago
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How Earth’s Surface and Interior are Connected to Freshwater Availability
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By NASA
1 Min Read Oral History with R. Walter Cunningham
Lunar module pilot Walter Cunningham writes with a space pen as he performs flight tasks on the ninth day of the Apollo 7 mission. Credits: NASA Selected for NASA’s third astronaut class in 1963, Cunningham served as the backup Lunar Module Pilot for Apollo 1. He piloted the 11-day flight of Apollo 7 in October 1968, the first manned flight test of the Apollo spacecraft. The crew executed maneuvers enabling them to practice for upcoming Apollo lunar orbit rendezvous missions and provided the first live television transmission of onboard crew activities. Cunningham served as the Chief of the Skylab branch under the Flight Crew Directorate at Johnson Space Center in 1969 until his retirement and move to the private sector in 1971.
Read more about R. Walter Cunningham
NASA Oral History, May 24, 1999 NASA Biography Apollo Astronaut Walter Cunningham Dies at 90 The transcripts available on this site are created from audio-recorded oral history interviews. To preserve the integrity of the audio record, the transcripts are presented with limited revisions and thus reflect the candid conversational style of the oral history format. Brackets and ellipses indicate where the text has been annotated or edited for clarity. Any personal opinions expressed in the interviews should not be considered the official views or opinions of NASA, the NASA History Office, NASA historians, or staff members.
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By NASA
1 Min Read Oral History with Karol J. Bobko
View of STS 51-D crew commander Karol Bobko training with the Arriflex 16mm camera. Credits: NASA A veteran of three space flights, Karol J. “Bo” Bobko was selected as an astronaut in 1969 and served as a crewmember on the Skylab Medical Experiments Altitude Test (SMEAT) 56-day ground simulation in preparation for the Skylab missions. He served in various positions supporting the Apollo-Soyuz Test Project and the first Approach and Landing Tests for the Space Shuttle before flying as the STS-6 pilot and as the mission commander on STS-51D and STS-51J.
Read more about Karol J. “Bo” Bobko
NASA Oral History, February 12, 2002 NASA Biography The transcripts available on this site are created from audio-recorded oral history interviews. To preserve the integrity of the audio record, the transcripts are presented with limited revisions and thus reflect the candid conversational style of the oral history format. Brackets and ellipses indicate where the text has been annotated or edited for clarity. Any personal opinions expressed in the interviews should not be considered the official views or opinions of NASA, the NASA History Office, NASA historians, or staff members.
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