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Climate change mystery solved: Ancient sea ice loss spurred Antarctic cold reversal

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June 22 (UPI) — A mysterious period of climate change, known as the Antarctic cold reversal, was triggered by the rapid loss of sea ice nearly 15,000 years ago, according to a study published Monday in the journal Nature Geoscience.

At the end of the last ice age, some 18,000 years ago, atmospheric carbon levels began to rise, Earth’s glaciers started receding and the world steadily warmed. But this period of warming didn’t proceed uninterrupted. It happened in fits and starts.

One fit, beginning 14,600 years ago, was particularly pronounced: the Antarctic cold reversal. After a period of greenhouse warming, atmospheric CO2 levels plateaued — remaining at 240 parts per million for 1,900 years.

Scientists weren’t sure what caused the plateau, but researchers recently found evidence of increased biological activity during the reversal period.

“We found that in sediment cores located in the sea-ice zone of the Southern Ocean biological productivity increased during this critical period, whereas it decreased farther north, outside of the sea-ice zone,” Michael Weber, researcher at the Institute for Geosciences at the University of Bonn in Switzerland, said in a news release. “It was now important to find out how climate records on the Antarctic continent depict this critical time period.”

To better understand how changes in ice patterns influenced the region’s biological activity and the Antarctic carbon cycle, an international team of researchers headed to Western Antarctica’s Patriot Hills Blue Ice Area in search of marine biomarkers trapped in ancient ice layers.

“The cause of this long plateau in global atmospheric CO2 levels may be fundamental to understanding the potential of the Southern Ocean to moderate atmospheric CO2,” said lead researcher Chris Fogwill.

“Whilst recent reductions in emissions due to the Covid-19 pandemic have shown that we can reduce CO2, we need to understand the ways in which CO2 levels have been stabilized by natural processes, as they may be key to the responsible development of geoengineering approaches and remain fundamental to achieving our commitment to the Paris Agreement,” said Fogwill, professor of glaciology and palaeoclimatology at Keele University in Britain.

Blue ice areas are formed when high winds push snow into large embankments. The combination of wind-drive snow transport, ice flow and sublimation leaves older, smoother and bluer ice exposed.

Many blue ice areas feature especially ancient ice, and some contain ice as much as 2.5 million years old, researchers say.

“Instead of drilling kilometers into the ice, we can simply walk across a blue ice area to travel back through time,” said researcher Chris Turney, a professor of climate change at the University of New South Wales. “This provides the opportunity to sample large volumes of ice necessary for studying new organic biomarkers and DNA that were blown from the Southern Ocean onto Antarctica and preserved in the blue ice.”

Analysis of the ice samples collected from the Patriot Hills revealed a growing abundance of marine organisms during the 1,900-year Antarctic cold reversal, researchers reported.

When scientists ran climate models fueled by paleoclimate data from the time period, their simulations showed the rise in biological activity coincided with dramatic seasonal changes in sea ice extent.

The research suggests sea ice losses triggered an increase in biological activity, which helped pull CO2 from the atmosphere and sequester it in the ocean.

In future studies, scientists said they hope to use their findings to improve climate change prediction models for the Southern Ocean and Antarctica.

“Our results highlight the role Antarctic sea ice plays in controlling global CO2, and demonstrate the need to incorporate such feedbacks into climate-carbon models,” researchers wrote in the study.



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Eight nations, including U.S., sign accords for moon missions

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ORLANDO, Fla., Oct. 13 (UPI) — Eight nations have signed NASA’s new framework to govern lunar exploration missions, the agency’s administrator, Jim Bridenstine, announced Tuesday.

By signing the agreement, the eight nations commit to peaceful activities on the moon and in travel to the moon.

Provisions in the Artemis Accords stipulate that nations, and private companies in those nations, will openly disclose plans for lunar missions, and mine resources on the moon in accordance with the international Outer Space Treaty that dates to 1967.

The accords also commit signing nations to render aid to other nations on the moon if necessary, to minimize space debris and to register all objects taken to the lunar surface.

In addition to the United States, Australia, Canada, Italy, Japan, Luxembourg, United Arab Emirates and Britain signed the Artemis Accords.

“We are one human race and we are in this together. The Accords help us to work together to benefit all,” Sarah Al Amiri, chair of the United Arab Emirates Council of Scientists, said in a live broadcast Tuesday.

Bridenstine had said in a press conference Monday that more nations are expected to sign the accords this year, and that he hopes all nations eventually will.

“As NASA, we always try to be very transparent and what our plans and policies are, and we think it’s good for all nations to be transparent with their plans,” Bridenstine said.

The new agreement comes as NASA plans to return astronauts to the moon in 2024, with further plans to establish a lunar base to tap water ice for possible long-term habitation.

NASA officials on Monday acknowledged they didn’t approach all space-faring nations in drafting the accords because the agency wanted to move quickly. NASA sought a few nations believed to have common values, said Mike Gold, associate administrator for NASA’s Office of International and Interagency Relations.

“We wanted to begin with a group substantive and large enough to make an impact,” Gold said. “It’s very challenging to do that with too large a group. Now that the text of the accords have been finalized we can broaden the coalition.”

Bridenstine said NASA couldn’t approach China, which already has landed two robotic missions on the moon, because federal law prohibits negotiations with China.

When asked how the accords would be enforced, Bridenstine said the intent of the agreement is to pre-empt conflict by being transparent.

“If one of the participants chooses to disregard the guidance, other participants … ultimately could be asked to leave the Artemis program, but I would hope that they will come to a better resolution,” Bridenstine said.

NASA’s 16 women astronauts — at least one likely to walk on moon

Tracy Caldwell Dyson pauses for a portrait in her spacesuit before going underwater in the Neutral Buoyancy Lab at NASA’s Johnson Space Center in Houston on July 8, 2019. Photo by Bill Ingalls/UPI

NASA’s 16 women astronauts — at least one likely to walk on moon

Tracy Caldwell Dyson pauses for a portrait in her spacesuit before going underwater in the Neutral Buoyancy Lab at NASA’s Johnson Space Center in Houston on July 8, 2019. Photo by Bill Ingalls/UPI



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Rising atmospheric dust across the Great Plains recalls lead up to the Dust Bowl

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Oct. 13 (UPI) — Atmospheric dust levels are rising 5 percent per year across the Great Plains, according to a new survey by scientists at the University of Utah.

The research, published this week in the journal Geophysical Research Letters, increased cropland conversion and expanded growing seasons are exposing more and more soil and wind erosion.

Authors of the new study suggest the phenomenon, if combined with drier climate conditions as a result of climate change, could yield conditions comparable to the Dust Bowl, the series of droughts and dust storms that devastated the Midwest during the 1930s.

“We can’t make changes to the earth surface without some kind of consequence just as we can’t burn fossil fuels without consequences,” lead study author Andy Lambert said in a news release.

“So while the agriculture industry is absolutely important, we need to think more carefully about where and how we plant,” said Lambert, a recent graduate of the University of Utah.

In the 1920s, farmers across the Great Plains converted massive amounts of grassland to farm tracts. When drought hit in the 1930s, extensive crop failures left newly plowed fields exposed to the wind, yielding waves of dust storms.

“These dust storms removed nutrients from the soil, making it more difficult for crops to grow and more likely for wind erosion to occur,” Lambert said.

Soaking rains eventually brought an end to the Dust Bowl, but much of the damage caused by erosion was permanent. Soils in some parts of the Great Plains have never recovered.

Three-quarters of a century later, around 2000, as demand for biofuels increased, farmers started clearing additional grassland to biofuel feedstocks.

Between 2006 and 2011, nearly 2,050 square miles of grassland across five Midwestern states was converted to farmland. Meanwhile, droughts have become longer and more across the Great Plains.

To gauge the risk of dust storms in the region, researchers amassed data from a variety of instruments designed to measure atmospheric haziness from both the ground up and space down. The data, from NASA satellites and two federally managed ground monitoring systems, showed the amount of dust in the atmosphere above the Great Plains has steadily increased over the last 20 years.

“The amount of increase is really the story here,” said study co-author Gannet Hallar, associate professor of atmospheric sciences. “That 5 percent a year over two decades, of course, is a hundred percent increase in dust loading. This is not a small signal to find.”

Scientists were also able to link rises in dust levels with crop expansion. Across Iowa, atmospheric dust increased predominantly in June and October, the planting and harvesting months for soybeans, the dominant crop. Across the southern Great Plains, where corn is more popular, the dust increases appeared in March and October.

“I think it’s fair to say that what’s happening with dust trends in the Midwest and the Great Plains is an indicator that the threat is real if crop land expansion continues to occur at this rate and drought risk does increase because of climate change,” Lambert says. “Those would be the ingredients for another Dust Bowl.”

Authors of the new study said their findings should serve as a warning to farmers and policy makers across the Midwest that proactive measures are needed to ensure history doesn’t repeat itself.



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NASA’s Kate Rubins, 2 cosmonauts dock with International Space Station

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Tracy Caldwell Dyson pauses for a portrait in her spacesuit before going underwater in the Neutral Buoyancy Lab at NASA’s Johnson Space Center in Houston on July 8, 2019. Photo by Bill Ingalls/UPI



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