How the rising earth in Antarctica will impact future sea level rise

The rising earth beneath the Antarctic Ice Sheet will likely become a major factor in future sea level rise, a new study suggests.

Despite feeling like a stationary mass, most solid ground is undergoing a process of deformation, sinking and rising in response to many environmental factors. In Antarctica, melting glacial ice means less weight on the bedrock below, allowing it to rise. How the rising earth interacts with the overlying ice sheet to affect sea level rise is not well-studied, said Terry Wilson, co-author of the study and a senior research scientist at the Byrd Polar and Climate Research Center at The Ohio State University.

In the new study, Wilson's colleagues at McGill University developed a model to predict how these interactions could impact global sea level, finding that if humans can lower greenhouse gas emissions and global warming is slowed, upward shifts in the solid earth could reduce Antarctica's contribution to sea level rise by about 40%, significantly bolstering the best case scenarios for global sea level rise. In this low-emissions scenario, land uplift slows the flow of ice from land to ocean, allowing for more of the ice sheet to be preserved.

Conversely, if humans are unable to lower carbon emissions in time, ice retreat will outpace uplift, pushing ocean water away from Antarctica and amplifying sea level rise. These events could significantly worsen the most dire models of projected sea level rise along populated coastlines, said Wilson.

"Our measurements show that the solid earth that forms the base of the Antarctic ice sheet is changing shape surprisingly quickly," said Wilson. "The land uplift from reduced ice on the surface is happening in decades, rather than over thousands of years."

The study was published today in Science Advances.

To arrive at these conclusions, the team developed a 3D model of the Earth's interior using geophysical field measurements from the Antarctic Network (ANET) of the Polar Earth Observing Network (POLENET) project. The mission is focused on studying the changing polar regions by collecting GPS and seismic data from an array of autonomous systems across Antarctica.

Researchers then performed a number of simulations to capture many possible evolutions of Antarctica's ice sheet and the extent of global sea level rise Earth may experience until the year 2500, according to those parameters.

"We can project what difference it actually will make if we all contribute to a low-emission scenario now, versus what's come to be called 'business as usual' emissions," said Wilson, who is also the lead investigator of the ANET-POLENET project.

She attributes the model's unprecedented level of detail to how deftly it incorporates data from Antarctica. GPS stations monitor how the land is moving and seismometers measure how fast seismic waves from earthquakes travel through the earth, yielding important insight into where the land uplift will be fast or slow.

Surprisingly, according to some of the team's GPS observations processed by researchers at Ohio State, Wilson said, the Antarctic Ice Sheet is currently experiencing a solid earth uplift of about 5 centimeters per year, about 5 times the rate that North America experiences.

Another significant aspect of the study is how the changes in Antarctica under different carbon emissions scenarios will impact coastlines around the world. Because sea level change will not be uniform, the study notes that nearly 700 million people around the world living in coastal regions will be most impacted by rising seas due to Antarctic ice loss.

Since some regions, such as small island nations, will be more vulnerable than others, mitigating environmental conditions like atmospheric and ocean warming is a vital issue for society, said Wilson.

"Many people are now more aware they're experiencing the effects of climate change," she said. "This work reinforces that our actions as individuals, nations and globally can make a difference in what kind of Earth our offspring will experience in their lifetimes."

The study results highlight how complex the relationship between the solid earth and the processes that happen atop it is, as well as the importance of continuing to gather enough data to make prompt and accurate predictions about what the next few centuries of our planet will look like.

"There's a lot of uncertainty in every model and every prediction that you make," said Wilson. "But to document how fast our world is changing, it's very important to continue advancing our ability to make predictions that are more certain, which is the only path that will allow us to tend to our future in a meaningful way."

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Enormous ice loss from Greenland glacier

Ground-based measuring devices and aircraft radar operated in the far northeast of Greenland show how much ice the 79° N-Glacier is losing. According to measurements conducted by the Alfred Wegener Institute, the thickness of the glacier has decreased by more than 160 metres since 1998. Warm ocean water flowing under the glacier tongue is melting the ice from below. High air temperatures cause lakes to form on the surface, whose water flows through huge channels in the ice into the ocean. One channel reached a height of 500 metres, while the ice above was only 190 metres thick, as a research team has now reported in the scientific journal The Cryosphere.

A rustic camp in northeast Greenland was one of the bases for deploying autonomous measuring devices with modern radar technology by helicopter in a part of the 79° N-Glacier that is difficult to access.

Measurement flights with the polar aircraft of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) and satellite data were also incorporated into a scientific study that has now been published in the scientific journal The Cryosphere. This study examines how global warming affects the stability of a floating ice tongue.

This is of great importance for the remaining ice shelves in Greenland as well as those in Antarctica, as instability of the ice shelf usually results in an acceleration of the ice flow, which would lead to a greater sea level rise.

"Since 2016, we have been using autonomous instruments to carry out radar measurements on the 79° N-Glacier, from which we can determine melt and thinning rates," says AWI glaciologist Dr Ole Zeising, the first author of the publication.

"In addition, we used aircraft radar data from 1998, 2018 and 2021 showing changes in ice thickness. We were able to measure that the 79° N-Glacier has changed significantly in recent decades under the influence of global warming."

The study shows how the combination of a warm ocean inflow and a warming atmosphere affects the floating ice tongue of the 79° N-Glacier in northeast Greenland.

Only recently, an AWI oceanography team published a modelling study on this subject.

The unique data set of observations now presented shows that extremely high melt rates occur over a large area near the transition to the ice sheet.

In addition, large channels form on the underside of the ice from the land side, probably because the water from huge lakes drains through the glacier ice.

Both processes have led to a strong thinning of the glacier in recent decades.

Due to extreme melt rates, the ice of the floating glacier tongue has become 32 % thinner since 1998, especially from the grounding line where the ice comes into contact with the ocean.

In addition, a 500-metre-high channel has formed on the underside of the ice, which spreads towards the inland.

The researchers attribute these changes to warm ocean currents in the cavity below the floating tongue and to the runoff of surface meltwater as a result of atmospheric warming.

A surprising finding was that melt rates have decreased since 2018.

A possible cause for this is a colder ocean inflow. "The fact that this system reacts on such short time scales is astonishing for systems that are actually inert such as glaciers," says Prof Dr Angelika Humbert, who is also involved in the study.

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80 mph speed record for glacier fracture helps reveal the physics of ice sheet collapse

There's enough water frozen in Greenland and Antarctic glaciers that if they melted, global seas would rise by many feet. What will happen to these glaciers over the coming decades is the biggest unknown in the future of rising seas, partly because glacier fracture physics is not yet fully understood.

A critical question is how warmer oceans might cause glaciers to break apart more quickly. University of Washington researchers have demonstrated the fastest-known large-scale breakage along an Antarctic ice shelf. The study, recently published in AGU Advances, shows that a 6.5-mile (10.5 kilometer) crack formed in 2012 on Pine Island Glacier -- a retreating ice shelf that holds back the larger West Antarctic ice sheet -- in about 5 and a half minutes. That means the rift opened at about 115 feet (35 meters) per second, or about 80 miles per hour.

"This is to our knowledge the fastest rift-opening event that's ever been observed," said lead author Stephanie Olinger, who did the work as part of her doctoral research at the UW and Harvard University, and is now a postdoctoral researcher at Stanford University. "This shows that under certain circumstances, an ice shelf can shatter. It tells us we need to look out for this type of behavior in the future, and it informs how we might go about describing these fractures in large-scale ice sheet models."

A rift is a crack that passes all the way through the roughly 1,000 feet (300 meters) of floating ice for a typical Antarctic ice shelf. These cracks are the precursor to ice shelf calving, in which large chunks of ice break off a glacier and fall into the sea. Such events happen often at Pine Island Glacier -- the iceberg observed in the study has long since separated from the continent.

"Ice shelves exert a really important stabilizing influence on the rest of the Antarctic ice sheet. If an ice shelf breaks up, the glacier ice behind really speeds up," Olinger said. "This rifting process is essentially how Antarctic ice shelves calve large icebergs."

In other parts of Antarctica, rifts often develop over months or years. But it can happen more quickly in a fast-evolving landscape like Pine Island Glacier, where researchers believe the West Antarctic Ice Sheet has already passed a tipping point on its collapse into the ocean.

Satellite images provide ongoing observations. But orbiting satellites pass by each point on Earth only every three days. What happens during those three days is harder to pin down, especially in the dangerous landscape of a fragile Antarctic ice shelf.

For the new study, the researchers combined tools to understand the rift's formation. They used seismic data recorded by instruments placed on the ice shelf by other researchers in 2012 with radar observations from satellites.

Glacier ice acts like a solid on short timescales, but it's more like a viscous liquid on long timescales.

"Is rift formation more like glass breaking or like Silly Putty being pulled apart? That was the question," Olinger said. "Our calculations for this event show that it's a lot more like glass breaking."

If the ice were a simple brittle material, it should have shattered even faster, Olinger said. Further investigation pointed to the role of seawater. Seawater in the rifts holds the space open against the inward forces of the glacier. And since seawater has viscosity, surface tension and mass, it can't just instantly fill the void. Instead, the pace at which seawater fills the opening crack helps slow the rift's spread.

"Before we can improve the performance of large-scale ice sheet models and projections of future sea-level rise, we have to have a good, physics-based understanding of the many different processes that influence ice shelf stability," Olinger said.

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Climate: Why disinformation is so persistent

Melting of glaciers, rising sea levels, extreme heat waves: the consequences of climate change are more visible than ever, and the scientific community has confirmed that humans are responsible. Yet studies show that a third of the population still doubts or disputes these facts. The cause is disinformation spread by certain vested interests. To try and prevent this phenomenon, a team from the University of Geneva (UNIGE) has developed and tested six psychological interventions on nearly 7,000 participants from twelve countries. The research, published in the journal Nature Human Behavior, highlights the extremely persuasive nature of disinformation and the need to strengthen our efforts to combat it.

Fighting disinformation about climate change is a major challenge for society.

Although scientific consensus on human responsibility -- reaffirmed by the sixth report of the Intergovernmental Panel on Climate Change (IPCC) -- has been in place for decades, a third of the population still doubts or disputes it. This phenomenon can be explained by the disinformation spread by certain companies and lobbies over the last 50 years.

''For instance, these messages can take the form of an unfounded questioning of the scientific consensus or an overestimation of the socio-financial burden of climate policies,'' explains Tobia Spampatti, a PhD Student and Teaching and Research Assistant in the Consumer Decision and Sustainable Behavior Lab (CDSB Lab) at the Faculty of Psychology and Educational Sciences and at the Swiss Center for Affective Sciences of the UNIGE.

Many psychological factors

This phenomenon weakens the support of a part of the population for climate policies.

To combat this, Tobia Spampatti and researchers from the UNIGE developed a theoretical framework to describe the formation and updating of (anti)scientific information.

This framework, built on previous theoretical takes on the psychology of misinformation (Philippe Mueller et al. and Ulrich Ecker et al. in 2022), takes into account the source of the message, its content, its recipients, and the psychological factors that can influence their processing.

This theoretical framework aims to identify the entry points for disinformation to access a person's ''psyche'', and can be used to intervene and block, or encourage, people to accept information.

''As individuals, we do not process scientific messages as neutral receivers of information, but by weighing them up against our prior beliefs, desired outcomes, emotional ties and socio-cultural and ideological backgrounds.

Depending on the configuration of these psychological factors, anti-scientific beliefs can be amplified and become resistant to correction,'' explains Tobia Spampatti, first author of the study.

Six preventive strategies put to the test

On this basis, the researchers developed six psychological intervention strategies aimed at preventing climate disinformation from affecting people's climate-related beliefs and behaviors.

They were tested on 6,816 participants in twelve different countries.

Each strategy was linked to a particular theme (scientific consensus, trust in climate scientists, transparent communication, moralizing climate action, accuracy, positive emotions towards climate action). The participants were divided into eight groups: six subjected to one of these strategies, one to disinformation without prevention, and a control group.

The ''trust in climate scientists'' group, for example, received verified information demonstrating the credibility of IPCC scientists.

The "transparent communication" group, meanwhile, was presented with information on both the advantages and the disadvantages of climate mitigation actions.

Each group was then exposed to twenty pieces of false or biased information, ten on climate science and ten on climate policy.

The UNIGE scientists then measured their impact after these preventive interventions by asking the participants about their feelings regarding climate mitigation actions.

Low preventive effect

''We found that the protective effect of our strategies is small and disappears after the second exposure to disinformation.

Climate disinformation used in this study has a negative influence on people's belief in climate change and their sustainable behaviour'', says Tobias Brosch, Associate Professor in the CDSB Lab at the Faculty of Psychology and Educational Sciences and at the Swiss Center for Affective Sciences in the UNIGE, and final author of the study.

''Disinformation is therefore extremely persuasive, seemingly more so than scientific information.

Only the 'accuracy' group, who were asked to think in depth about the accuracy of the information they encountered online, showed a slight advantage''.

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Increased West Antarctic Ice Sheet melting 'unavoidable'

Scientists ran simulations on the UK's national supercomputer to investigate ocean-driven melting of the West Antarctic Ice Sheet: how much is unavoidable and must be adapted to, and how much melting the international community still has control over through reduction of greenhouse gas emissions.

Taking into account climate variability like El Niño, they found no significant difference between mid-range emissions scenarios and the most ambitious targets of the 2015 Paris Agreement. Even under a best-case scenario of 1.5°C global temperature rise, melting will increase three times faster than during the 20th century.

The West Antarctic Ice Sheet is losing ice and is Antarctica's largest contributor to sea-level rise. Previous modelling finds this loss could be driven by warming of the Southern Ocean, particularly the Amundsen Sea region. Collectively the West Antarctic Ice Sheet contains enough ice to raise global mean sea-level by up to five metres.

Around the world millions of people live near the coast and these communities will be greatly impacted by sea level rise. A better understanding of the future changes will allow policymakers to plan ahead and adapt more readily.

Lead author Dr Kaitlin Naughten, a researcher at the British Antarctic Survey says:

"It looks like we've lost control of melting of the West Antarctic Ice Sheet. If we wanted to preserve it in its historical state, we would have needed action on climate change decades ago. The bright side is that by recognising this situation in advance, the world will have more time to adapt to the sea level rise that's coming. If you need to abandon or substantially re-engineer a coastal region, having 50 years lead time is going to make all the difference."

The team simulated four future scenarios of the 21st century, plus one historical scenario of the 20th century. The future scenarios either stabilised global temperature rise at the targets set out by the Paris Agreement, 1.5°C and 2°C, or followed standard scenarios for medium and high carbon emissions.

All scenarios resulted in significant and widespread future warming of the Amundsen Sea and increased melting of its ice-shelves. The three lower-range scenarios followed nearly identical pathways over the 21st century. Even under the best-case scenario, warming of the Amundsen Sea sped up by about a factor of three, and melting of the floating ice shelves which stabilise the inland glaciers followed, though it did begin to flatten by the end of the century.

The worst-case scenario had more ice shelf melting than the others, but only after 2045. The authors heed that this high fossil fuel scenario, where emissions increase rapidly, is considered unlikely to occur.

This study presents sobering future projections of Amundsen Sea ice-shelf melting but does not undermine the importance of mitigation in limiting the impacts of climate change.

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Using evidence from last Ice Age, scientists predict effects of rising seas on coastal habitats

The rapid sea level rise and resulting retreat of coastal habitat seen at the end of the last Ice Age could repeat itself if global average temperatures rise beyond certain levels, according to an analysis by an international team of scientists from more than a dozen institutions, including Rutgers.

In a study published in Nature, scientists reported how ancient coastal habitats adapted as the last glacial period ended more than 10,000 years ago and projected how they are likely to change with this century's predicted sea level rise. They conducted their analysis by examining the ocean sediments of ancient shorelines from a time when oceans rose rapidly, mainly because of melting ice sheets in the Northern Hemisphere. This examination allowed them to infer how ancient coastal habitats changed and formed the basis of improved predictions about the present.

"Every ton of carbon dioxide humankind emits turns up the global thermostat, which in turn increases the pace of global sea level rise," said Robert Kopp, a Distinguished Professor in the Department of Earth and Planetary Sciences in the Rutgers School of Arts and Sciences and an author of the study. "The faster the oceans rise, the greater the threat to tidal marshes, mangroves and coral reefs around the world. For example, in our analysis, most tidal marshes are likely to be able to keep up with sea level rise under 1.5 degrees Celsius [2.7 degrees Fahrenheit] of warming, but two-thirds are unlikely to be able to keep up with 2 degrees Celsius [3.6 degrees Fahrenheit] of warming."

The temperature ranges mentioned in the study are significant because they relate directly to the Paris Agreement, an international treaty on climate change adopted in 2015, said Kopp, who is also the director of the Megalopolitan Coastal Transformation Hub and co-director of the University Office of Climate Action. The goal of the Paris treaty is to substantially reduce carbon emissions worldwide to limit the global temperature increase in this century to 2 degrees Celsius above preindustrial levels while pursuing efforts to limit the increase even further to 1.5 degrees Celsius.

The study predicted higher global temperatures will provoke sea level rises that will lead to instability and profound changes to coastal ecosystems, including tidal marshes, mangrove forests, coral reefs and coral islands.

Tidal marshes -- low-lying areas flooded and drained by tidal salt water -- protect many of the world's coastlines. They sequester pollutants, absorb carbon dioxide and protect nearby communities from storm surge and flooding. They are common along the Atlantic shores of North America. Large expanses of tidal marshes line New Jersey's coast.

"This new paper provides evidence from geological history that, without mitigation and under current projections, tidal marshes will not have the capacity to adjust," said Judith Weis, a Professor Emerita of Biological Sciences at Rutgers-Newark who isn't an author of the study but is an expert on tidal marshes. "For many tidal marshes in New Jersey, this is not a prediction but a description of the present situation, in which sea level is rising faster than the marshes can increase their elevation. This makes it even more vital to reduce climate change as rapidly as possible."

Tidal marshes and mangrove forests adapt to rising seas by accumulating sediment and moving slowly inland.

"Mangroves and tidal marshes act as a buffer between the ocean and the land -- they absorb the impact of wave action, prevent erosion and are crucial for biodiversity of fisheries and coastal plants," said Neil Saintilan, the paper's lead author and a professor at Macquarie University in Sydney, Australia. "When the plants become water-logged due to higher sea levels, they start to flounder."

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Thinning ice sheets may drive sharp rise in subglacial waters

Two Georgia Tech researchers, Alex Robel and Shi Joyce Sim, have collaborated on a new model for how water moves under glaciers. The new theory shows that up to twice the amount of subglacial water that was originally predicted might be draining into the ocean -- potentially increasing glacial melt, sea level rise, and biological disturbances.

The paper, published in Science Advances, "Contemporary Ice Sheet Thinning Drives Subglacial Groundwater Exfiltration with Potential Feedbacks on Glacier Flow," is co-authored by Colin Meyer (Dartmouth), Matthew Siegfried (Colorado School of Mines), and Chloe Gustafson (USGS).

While there are pre-existing methods to understand subglacial flow, these techniques involve time-consuming computations. In contrast, Robel and Sim developed a simple equation, which can predict how fast exfiltration, the discharge of groundwater from aquifers under ice sheets, using satellite measurements of Antarctica from the last two decades.

"In mathematical parlance, you would say we have a closed form solution," explains Robel, an assistant professor in the School of Earth and Atmospheric Sciences. "Previously, people would run a hydromechanical model, which would have to be applied at every point under Antarctica, and then run forward over a long time period." Since the researchers' new theory is a mathematically simple equation, rather than a model, "the entirety of our prediction can be done in a fraction of a second on a laptop," Robel says.

Robel adds that while there is precedence for developing these kinds of theories for similar kinds of models, this theory is specific in that it is for the particular boundary conditions and other conditions that exist underneath ice sheets. "This is, to our knowledge, the first mathematically simple theory which describes the exfiltration and infiltration underneath ice sheets."

"It's really nice whenever you can get a very simple model to describe a process -- and then be able to predict what might happen, especially using the rich data that we have today. It's incredible" adds Sim, a research scientist in the School of Earth and Atmospheric Sciences. "Seeing the results was pretty surprising."

One of the main arguments in the paper underscores the potentially large source of subglacial water -- possibly up to double the amount previously thought -- that could be affecting how quickly glacial ice flows and how quickly the ice melts at its base. Robel and Sim hope that the predictions made possible by this theory can be incorporated into ice sheet models that scientists use to predict future ice sheet change and sea level rise.

A dangerous feedback cycle

Aquifers are underground areas of porous rock or sediment rich in groundwater. "If you take weight off aquifers like there are under large parts of Antarctica, water will start flowing out of the sediment," Robel explains, referencing a diagram Sim created. While this process, known as exfiltration, has been studied previously, focus has been on the long time scales of interglacial cycles, which cover tens of thousands of years.

There has been less work on modern ice sheets, especially on how quickly exfiltration might be occurring under the thinning parts of the current-day Antarctic ice sheet. However, using recent satellite data and their new theory, the team has been able to predict what exfiltration might look like under those modern ice sheets.

"There's a wide range of possible predictions," Robel explains. "But within that range of predictions there is the very real possibility that groundwater may be flowing out of the aquifer at a speed that would make it a majority, or close to a majority of the water that is underneath the ice sheet."

If those parameters are correct, that would mean there's twice as much water coming into the subglacial interface than previous estimates assumed.

Ice sheets act like a blanket, sitting over the warm earth and trapping heat on the bottom, away from Antarctica's cold atmosphere -- and this means that the warmest place in the Antarctic ice sheet is at the bottom of a sheet, not on the surface. As an ice sheet thins, the warmer underground water can exfiltrate more readily, and this heat gradient can accelerate the melting that an ice sheet experiences.

"When the atmosphere warms up, it takes tens of thousands of years for that signal to diffuse through an ice sheet of the size of the thickness of the Antarctic ice sheet," Robel explains. "But this process of exfiltration is a response to the already-ongoing thinning of the ice sheet, and it's an immediate response right now."

Broad implications

Beyond sea level rise, this additional exfiltration and melt has other implications. Some of the places of richest marine productivity in the world occur off the coast of Antarctica, and being able to better predict exfiltration and melt could help marine biologists better understand where marine productivity is occurring, and how it might change in the future.

Robel also hopes this work will open the doorway to more collaborations with groundwater hydrologists who may be able to apply their expertise to ice sheet dynamics, while Sim underscores the need for more fieldwork.

"Getting the experimentalists and observationalists interested in trying to help us better constrain some of the properties of these water-laden sediments -- that would be very helpful," Sim says. "That's our largest unknown at this point, and it heavily influences the results."

"It's really interesting how there's a potential to draw heat from deeper in the system," she adds. "There's quite a lot of water that could be drawing more heat out, and I think that there's a heat budget there that could be interesting to look at."

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We've pumped so much groundwater that we've nudged Earth's spin

By pumping water out of the ground and moving it elsewhere, humans have shifted such a large mass of water that the Earth tilted nearly 80 centimeters (31.5 inches) east between 1993 and 2010 alone, according to a new study published in Geophysical Research Letters, AGU's journal for short-format, high-impact research with implications spanning the Earth and space sciences.

Based on climate models, scientists previously estimated humans pumped 2,150 gigatons of groundwater, equivalent to more than 6 millimeters (0.24 inches) of sea level rise, from 1993 to 2010. But validating that estimate is difficult.

One approach lies with the Earth's rotational pole, which is the point around which the planet rotates. It moves during a process called polar motion, which is when the position of the Earth's rotational pole varies relative to the crust. The distribution of water on the planet affects how mass is distributed. Like adding a tiny bit of weight to a spinning top, the Earth spins a little differently as water is moved around.

"Earth's rotational pole actually changes a lot," said Ki-Weon Seo, a geophysicist at Seoul National University who led the study. "Our study shows that among climate-related causes, the redistribution of groundwater actually has the largest impact on the drift of the rotational pole."

Water's ability to change the Earth's rotation was discovered in 2016, and until now, the specific contribution of groundwater to these rotational changes was unexplored. In the new study, researchers modeled the observed changes in the drift of Earth's rotational pole and the movement of water -- first, with only ice sheets and glaciers considered, and then adding in different scenarios of groundwater redistribution.

The model only matched the observed polar drift once the researchers included 2150 gigatons of groundwater redistribution. Without it, the model was off by 78.5 centimeters (31 inches), or 4.3 centimeters (1.7 inches) of drift per year.

"I'm very glad to find the unexplained cause of the rotation pole drift," Seo said. "On the other hand, as a resident of Earth and a father, I'm concerned and surprised to see that pumping groundwater is another source of sea-level rise."

"This is a nice contribution and an important documentation for sure," said Surendra Adhikari, a research scientist at the Jet Propulsion Laboratory who was not involved in this study. Adhikari published the 2016 paper on water redistribution impacting rotational drift. "They've quantified the role of groundwater pumping on polar motion, and it's pretty significant."

The location of the groundwater matters for how much it could change polar drift; redistributing water from the midlatitudes has a larger impact on the rotational pole. During the study period, the most water was redistributed in western North America and northwestern India, both at midlatitudes.

Countries' attempts to slow groundwater depletion rates, especially in those sensitive regions, could theoretically alter the change in drift, but only if such conservation approaches are sustained for decades, Seo said.

The rotational pole normally changes by several meters within about a year, so changes due to groundwater pumping don't run the risk of shifting seasons. But on geologic time scales, polar drift can have an impact on climate, Adhikari said.

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