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Human impact on Earth’s tilt leaves researchers ‘surprised and concerned’

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Humans pumped and displaced so much groundwater in just two decades that we shifted the tilt of Earth’s axis, new research suggests.

Earth’s rotational pole — the point around which the planet rotates — shifts with changes in the distribution of mass across the globe, wobbling and wandering in a process called polar motion. While scientists knew that changes in water distribution resulting from climate change could contribute to polar motion, the impact of groundwater depletion was unknown.

Now, researchers estimate that by pumping 2,150 gigatons of water — almost enough water to fill Lake Victoria in Africa, and equivalent to the weight of 5.5 million Empire State Buildings  — from underground layers of water-saturated rock known as aquifers, humans caused a “pretty significant” eastward shift of 31 inches (80 centimeters) in Earth’s rotational pole between 1993 and 2010.

That’s because groundwater used for irrigation and other human activities eventually ends up in the ocean, which redistributes mass from where the water was taken to other parts of the globe.

Related: Earth tipped on its side (and back again) in ‘cosmic yo-yo’ 84 million years ago

“Earth’s rotational pole actually changes a lot,” research leader Ki-Weon Seo, a geophysicist at Seoul National University in South Korea, said in a statement. “Our study shows that among climate-related causes, the redistribution of groundwater actually has the largest impact on the drift of the rotational pole.”

What’s more, the extracted groundwater that ended up in the oceans may have boosted global sea level rise by around 0.25 inch (6.24 millimeters). “Groundwater depletion is a significant contributor to sea level rise,” the researchers wrote in the study, published June 15 in the journal Geophysical Research Letters.

The model with groundwater redistribution (solid blue arrow) was a better match for the observed polar motion (solid red arrow) than the model without groundwater redistribution (dashed blue arrow). (Image credit: Seo et al. (2023), Geophysical Research Letters)

Globally, roughly 70% of the water pumped from the ground is used for irrigation, but only half of that trickles back down to replenish aquifers and other freshwater sources. The other half evaporates and ends up in the ocean through rainfall.

To determine how much groundwater depletion and resulting sea level rise contributed to polar drift, geophysicists built a model of polar motion that accounted for shifts in water mass associated with thinning ice sheets, melting glaciers and water storage in reservoirs.

When they excluded groundwater redistribution from the model, the results did not match observed eastward polar drift and, instead, predicted a much more westward tilt.

When they added the 2,150 gigatons of water from aquifers into the model, the results matched up with recorded observations of Earth’s eastward drift.

“This is a nice contribution and an important documentation for sure,” said Surendra Adhikari, a research scientist at NASA’s Jet Propulsion Laboratory and co-author of a 2016 study in the journal Science Advances that looked into the impact of water redistribution on polar drift.

“They’ve quantified the role of groundwater pumping on polar motion, and it’s pretty significant,” Adhikari said in the statement.

Other “non-negligible” changes in water and mass distribution may have played a role in polar motion between 1993 and 2010 — including shifts in natural lake levels, mantle convection and earthquakes. However, these are difficult to quantify, and no global database currently exists, the authors wrote in the study.

While polar shifts recorded in the last few decades are unlikely to affect the length of days or seasons, the finding illustrates just how much water humans have pumped from the ground. “I’m concerned and surprised,” Seo said in the statement.

 

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The body of a Ugandan Olympic athlete who was set on fire by her partner is received by family

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NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.

Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.

She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.

Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.

“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.

It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.

Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.

Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.

Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.

“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.

He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.

Kenya’s high rates of violence against women have prompted marches by ordinary citizens in towns and cities this year.

Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.

The Canadian Press. All rights reserved.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.

Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.

Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.

The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.

The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.

It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.

Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.

Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.

Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.

Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.

Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.

The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”

The Canadian Press. All rights reserved.

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B.C. sets up a panel on bear deaths, will review conservation officer training

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VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.

Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”

Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.

“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.

B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.

Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.

Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.

Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.

“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”

Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”

“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.

Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.

“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.

This report by The Canadian Press was first published Sept. 9, 2024.

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