Sharp depletion in soil moisture drives land water to flow into oceans, contributing to sea level rise
The increasing frequency of once-in-a-decade agricultural and ecological drought has underscored the urgency of studying hydrological changes. A research team from the Department of Land Surveying and Geo-informatics of The Hong Kong Polytechnic University (PolyU) has collaborated with international experts to analyse the estimated changes in land water storage over the past 40 years by utilising space geodetic observation technology and global hydrological change data. This innovative method has revealed a rapid depletion in global soil moisture, resulting in a significant amount of water flowing into the oceans, leading to a rise in sea levels. The research provides new insights into the driving factors behind the alarming reduction in terrestrial water storage and rise in sea levels. The findings have been published in the international journal Science .
Since polar motion reflects mass redistribution within the Earth system, integrating models and observations across the atmosphere, hydrosphere and lithosphere is crucial. However, previous challenges in measuring terrestrial water storage, particularly groundwater and root zone soil moisture, limited understanding of hydrological depletion at continental scales. Prof. Jianli CHEN, Professor of the PolyU Department of Land Surveying and Geo-informatics and core member of the Research Institute for Land and Space and the international team employed satellite altimetry and gravity missions, including the Gravity Recovery and Satellite Experiment (GRACE), and GRACE Follow-On, to enable continental-scale observations of terrestrial water storage variations. By integrating this with global mean sea levels and polar motion data, the team has explored terrestrial water storage depletion patterns. Notably, this study introduced novel methods for estimating global soil moisture, which improves the accuracy of continental and global scale modeling to enable a more effective understanding of soil moisture variations under climate change.
The melting of Greenland's ice sheet is recognised as the largest single contributor to the rise in global sea levels, adding approximately 0.8mm annually. This study reveals that between 2000 and 2002, the global terrestrial water storage significantly declined, with a total of 1,614 billion tons of water lost to the oceans, which is twice as much as resulting from the current melting of Greenland ice, and equivalent to a 4.5mm rise in sea levels. Since then, the rapid loss of terrestrial water storage has been followed by a more gradual but continuous depletion, with no signs of recovery.
In addition, compared to the period from 1979 to 1999, a notable decline in global average soil moisture was observed from 2003 to 2021. Between 2003 and 2011, the Earth's pole shifted 58cm toward 93° East Longitude, demonstrating that the continued decline in soil moisture is leading to a reduction in terrestrial water storage.
The team also pointed out that precipitation deficits and stable evapotranspiration caused by global warming, changing rainfall patterns and increasing ocean temperatures are likely the key factors for the abrupt decline in terrestrial water storage. The ERA5-Land soil moisture data of the European Centre for Medium-Range Weather Forecasts' corroborates these findings, showing substantial terrestrial water storage losses in Africa, Asia, Europe, and South America. In Asia and Europe, the affected areas expanded from northeastern Asia and eastern Europe to broader regions across East and Central Asia, as well as Central Europe, following the sharp water storage depletion observed between 2000 and 2002. Read More Evidence of geothermal activity within icy dwarf planets
With increasing agricultural irrigation in regions such as northeast China and the western United States, and global greening, soil moisture may further diminish in semi-arid areas with intensive agriculture and high levels of greening. The team suggests the need for improved land surface models which consider these factors for a more comprehensive understanding of long- term changes in terrestrial water storage.
Prof. Jianli Chen said, 'Sea level change and Earth rotation serve as indicators of large-scale mass changes in the Earth system. Accurately measured sea level change and variation in Earth rotation provide a unique tool for monitoring large-scale mass changes in the global water cycle. By integrating multiple modern space geodetic observations, it enables comprehensive analysis of the driving factors behind changes in terrestrial water storage and sea level rise. This, in turn, provides reliable data for climate and Earth system science experts to further investigate drought issues, aiding authorities in formulating water resource management and climate change mitigation strategies to address new challenges posed by climate change.'
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Yahoo
an hour ago
- Yahoo
The Sun's Fury Is Making SpaceX Satellites Plummet From The Sky
The Sun is the angriest it's been in a while – and it's taking out that rage on the thousands of tiny satellites that make up SpaceX's Starlink fleet. A new analysis of Starlink satellites falling from the sky has revealed a distinct pattern: as the Sun escalated towards the peak of its activity cycle between 2020 and 2024, so too did the number of satellite falls as a direct result of that activity. A team of scientists, led by space physicist Denny Oliveira of the NASA Goddard Space Flight Center, studied 523 Starlink satellites that fell back down towards Earth during that time, and found a clear link with the Sun. "We clearly show that the intense solar activity of the current solar cycle has already had significant impacts on Starlink reentries," they write in their paper. "This is a very exciting time in satellite orbital drag research, since the number of satellites in low-Earth orbit and solar activity are the highest ever observed in human history." The solar cycle is an 11-year cycle of fluctuations in the Sun's activity that centers around a periodic magnetic reversal of the solar poles. It primarily manifests as sunspots, solar flares, and coronal mass ejections that steadily increase towards solar maximum (when the poles flip), and then wanes to a minimum before inching back up again. It's just the Sun's normal way to be, and we're currently at the peak of the 25th cycle since we started keeping track of them. It's actually been a pretty strong cycle; not the strongest on record, but still displaying much more solar activity than scientists predicted at its beginning. This means that its effects on Earth have been pretty strong. You may have noticed a lot of aurora activity; that's the effect of solar particles pummeling Earth's atmosphere, borne by coronal mass ejections and the solar wind. But the increase in solar activity has another, less noticeable effect: the increase in solar ejections buffeting the upper atmosphere heats it up significantly. We don't notice it here on the surface. But the increased energy puffs up the atmosphere – enough to increase the amount of drag on spacecraft in low-Earth orbit. This means they cannot hold course at their current trajectory, and need to make adjustments to remain in the sky. To be clear, all satellites in low-Earth orbit are vulnerable to the increase in drag associated with solar activity. To date, however, SpaceX has launched 8,873 Starlink satellites into low-Earth orbit, of which 7,669 remain operational. These sheer numbers provide an excellent laboratory for studying the effect of solar maximum on satellites in low-Earth orbit. "Here, we use … Starlink orbital data to perform a superposed epoch analysis of orbital altitudes and velocities in order to identify impacts caused by storms with different intensities," the researchers write. "The Starlink reentries coincide with the rising phase of solar cycle 25, a period with increasing solar activity." SpaceX first started launching Starlink satellites in 2019, and the first atmospheric reentries began in 2020. Initially these figures stayed relatively low. There were just two in 2020. In 2021, 78 satellites fell; 99 in 2022, and 88 in 2023. But then 2024 saw a whopping increase – a total of 316 Starlink satellites fell out of the sky. The researchers grouped these reentries according to the geomagnetic conditions at the time – that is, how powerfully solar activity was affecting Earth. Oddly, some 72 percent of all reentries occurred during weak geomagnetic conditions, not the powerful geomagnetic storms. This, the researchers found, was because of the cumulative effect of drag over the rising period of the solar cycle. Rather than being taken down in one fell swoop, the orbits of these satellites degraded subtly over time. Meanwhile, the satellites that did fall during strong geomagnetic conditions fell faster than those that fell in weaker conditions. It's fascinating stuff, actually. We don't have a lot of data on this phenomenon; the work of Oliveira and his colleagues may help design strategies to mitigate the orbital decay induced by solar activity, keeping satellites in low-Earth orbit where they should be (and not, for example, smacking into other satellites and triggering a nasty Kessler cascade). "Our results are promising because they point in the direction of using short-cadence Starlink data (precise orbit determination, neutral mass density, ram direction area, drag coefficient) for the improvement of orbital drag models during geomagnetic storms, particularly during extreme events," the researchers write. The paper has been accepted for publication in Frontiers in Astronomy and Space Science, and is available on arXiv. Astronomers Just Discovered The Biggest Explosions Since The Big Bang Titan's Atmosphere 'Wobbles Like a Gyroscope' – And No One Knows Why A 'Crazy Idea' About Pluto Was Just Confirmed in a Scientific First
Yahoo
2 hours ago
- Yahoo
Humans nearly went extinct 1 million years ago, but we don't know why
If you purchase an independently reviewed product or service through a link on our website, BGR may receive an affiliate commission. A study published in 2023 suggests that nearly 1 million years ago, humanity almost ceased to exist. This potential mass extinction event was discovered by researchers when they began analyzing the genetic data of 3,145 modern humans. The researchers suggest that the ancient population may have been reduced to roughly 1,200 humans. Overall, the researchers believe that there could have been a bottleneck somewhere between 930,000 to 813,000 years ago, which led to a 98.7% reduction of humans on Earth. Unfortunately, narrowing down the exact cause of this bottleneck is still impossible, but it's likely climate changes could have been at the root of the event. Today's Top Deals Best deals: Tech, laptops, TVs, and more sales Best Ring Video Doorbell deals Memorial Day security camera deals: Reolink's unbeatable sale has prices from $29.98 Scientists suspect that when the world transitioned to the middle of the Pleistocene period, and the Earth cooled dramatically, it could have led to prolonged cold periods that killed off most humans. Combine that with droughts and widespread famine, and it would have been a recipe for a mass extinction event capable of wiping out humans. The researchers posit that humans may have been driven into smaller, more isolated communities, where they found themselves competing with each other for survival in the increasingly dangerous and challenging environment. Sadly, fossils from this point in time are scarce, making it hard to uncover information about the event or exactly how close humans came to being extinct. The findings also suggest that around 813,000 years ago, more hospitable climates may have been a big part of what allowed human populations to skyrocket once more. The researchers claim that as the conditions improved, humans may have branched out again, and the bottleneck may have faded. While these findings raise a lot of interesting questions, it's hard to verify all of the claims with the current data that's available. Hopefully new discoveries, like those of extinct human species, will give us more information about that time period and human evolution as a whole. More Top Deals Amazon gift card deals, offers & coupons 2025: Get $2,000+ free See the
Yahoo
5 hours ago
- Yahoo
Why Rocket Lab Corp. (RKLB) Soared On Friday
We recently published a list of . In this article, we are going to take a look at where Rocket Lab Corp. (NASDAQ:RKLB) stands against other Friday's best-performing stocks. Rocket Lab grew its share prices by 9.34 percent on Friday to finish at $28.92 apiece as investors loaded up portfolios ahead of its launch of a new mission on Tuesday. Rocket Lab Corp. (NASDAQ:RKLB) is scheduled to launch The Mountain God Guards mission for the Institute for Q-shu Pioneers of Space, Inc. (iQPS), a Japan-based Earth imaging company, through 'Electron,' the world's most frequently launched orbital small rocket. The mission will launch a single synthetic aperture radar imaging satellite called QPS-SAR-11 to a 575-kilometer circular Earth orbit, which will join the rest of the iQPS constellation in providing high-resolution images and Earth monitoring services globally. A launch pad atop a grassy hill, smoke filled sky from a successful voyage to space. The launch will take place at Rocket Lab Corporation's (NASDAQ:RKLB) Launch Complex 1 in New Zealand. Rocket Lab Corporation (NASDAQ:RKLB) said that The Mountain God Guards will mark its 8th mission for this year alone, its 4th out of the 8 missions dedicated to iQPS, its 66th Electron launch overall, and the 227th satellite delivered to space. Overall, RKLB ranks 9th on our list of Friday's best-performing stocks. While we acknowledge the potential of RKLB as an investment, our conviction lies in the belief that some AI stocks hold greater promise for delivering higher returns and have limited downside risk. If you are looking for an extremely cheap AI stock that is also a major beneficiary of Trump tariffs and onshoring, see our free report on the best short-term AI stock. READ NEXT: 20 Best AI Stocks To Buy Now and 30 Best Stocks to Buy Now According to Billionaires. Disclosure: None. This article is originally published at Insider Monkey.
