By Hannah Richter , Science.  Excerpt: A simple idea underpins an audacious intervention to augment Arctic sea ice and slow the climate feedback loop accelerating its disappearance. Drill holes through a floe, pump seawater onto its surface, and let the cold do the rest. The first results from two field tests show the technique can thicken the ice. But they also show those gains don’t last. The added ice—about 30 centimeters—is equivalent to decades of thinning from global warming. But ocean heat and surface slush erased the buffers soon after they formed. The tests, which were reported  last week in the  Journal of Geophysical Research: Oceans  and  in a recent preprint , show how difficult it would be to meaningfully expand the strategy across the Arctic, says Leigh Stearns, a glaciologist at the University of Pennsylvania who was not involved with the studies. The “effort to do these tests over a really small area was pretty enormous,” she says. “The thought ...

By Ferris Jabr, The New York Times.  Excerpt: On a hot February morning, that ship and two smaller companion barges — nicknamed Big Daddy and the Twins — roamed a bay within the Palm Islands cluster, off the northeastern coast of Australia. Each pumped seawater aboard, pressurized it and sprayed it into the air through hundreds of tiny nozzles arrayed on metal frames. Dense plumes of fog billowed from all three vessels, forming long white strands that eventually converged into a seamless cloak. ...Since 2016, Harrison and his colleagues have been investigating whether it is possible to reduce coral bleaching in the Great Barrier Reef by altering the weather above it. ...Theoretically, machine-generated fog and artificially brightened clouds can shade and cool the water in which corals live, sparing them much of that stress. ...The failure to prevent the planet’s average temperature from reaching 1.5 degrees Celsius above the preindustrial base line, and the progressively obvious an...

By Hannah Richter , Science.  Excerpt: ...proposals to cool the planet through “geoengineering” tend to be controversial. ...In a modeling study published this month in Geophysical Research Letters, scientists report that  shooting 5 million tons of diamond dust into the stratosphere each year could cool the planet by 1.6ºC —enough to stave off the worst consequences of global warming. The scheme wouldn’t be cheap, however: experts estimate it would cost nearly $200 trillion over the remainder of this century—far more than traditional proposals to use sulfur particles....  Full article at https://www.science.org/content/article/are-diamonds-earth-s-best-friend-gem-dust-could-cool-planet-and-cost-trillions .

By Brad Plumer  and  Raymond Zhong . The New York Times.  Excerpt: In a quiet patch of forest in Nova Scotia, a company is building a machine designed to help slow global warming by transforming Earth’s rivers and oceans into giant sponges that absorb carbon dioxide from the air. When switched on later this year, the machine will grind up limestone inside a tall green silo and release the powder into the nearby West River Pictou, creating a chalky plume that should dissolve within minutes. ...adding limestone converts some of that carbon dioxide into a stable molecule that instead stays underwater and washes into the sea, where it should remain trapped for thousands of years. ...Toying with ocean chemistry also carries unknown risks. Some environmental groups worry that even early experiments with these techniques could threaten fish and other aquatic life. ...In the 1970s and ’80s, industrial pollution made rainfall more acidic, which poisoned lakes and streams around th...

By Warren Cornwall , Science.  Excerpt: Geoengineering study that would disperse alkaline chemicals off Cape Cod draws environmental opposition. Adam Subhas ...has spent much of his career as a chemical oceanographer at Woods Hole Oceanographic Institution (WHOI), quietly studying how seawater can naturally offset global warming by absorbing carbon dioxide (CO 2 ). Now, Subhas has been thrust into a heated public debate. Next month he and his colleagues want to dump tons of caustic chemicals off the coast of Massachusetts to see whether they can boost the ocean’s uptake of CO 2 . They’re seeking what would be the first-ever regulatory approval for such a study from the U.S. Environmental Protection Agency (EPA). But some nearby residents and environmental groups, worried about safety, have pressed EPA to delay or halt the study. “It’s been a new journey to interact with reporters and the public and everyone at this level and at this intensity,” Subhas says. ...The natural alkalinit...

https://www.sfchronicle.com/weather/article/geoengineering-cloud-research-alameda-19368199.php By Anthony Edwards , San Francisco Chronicle.  Excerpt: In Alameda [CA], scientists are embarking on a novel attempt to cool the Earth — by spraying salt into clouds. The work, known as marine cloud brightening, is controversial and is just one method of geoengineering — which describes interventions meant to slow Earth’s warming. But proponents say the technology may be needed to mitigate climate change. To brighten clouds, researchers spray microscopic sea salt into the air over the ocean to boost clouds’ reflectivity. This means less sunlight is absorbed, leading to a planetary cooling effect. ...Scientists hypothesize that by manually increasing the number of particles in the atmosphere, clouds will reflect more sunlight back to space, causing Earth to cool. ...Scientists like Russell say that before more drastic solutions are deployed, the focus should be on reining in gree...

https://www.nytimes.com/2024/03/31/climate/climate-change-carbon-capture-ccs.html By David Gelles , The New York Times.  Excerpt: On a windswept Icelandic plateau, an international team of engineers and executives is powering up an innovative machine designed to alter the very composition of Earth’s atmosphere. If all goes as planned, the enormous vacuum will soon be sucking up vast quantities of air, stripping out carbon dioxide and then locking away those greenhouse gases deep underground in ancient stone — greenhouse gases that would otherwise continue heating up the globe. ...Global temperatures are now expected to rise as much as 4 degrees Celsius, or more than 7 degrees Fahrenheit, by the end of the century. That has given new weight to what some people call geoengineering, though that term has become so contentious its proponents now prefer the term “climate interventions.” ...Many of the projects are controversial. A plant similar to the one in Iceland, but far larger, is b...

https://eos.org/features/can-submerging-seaweed-cool-the-climate By Saima May Sidik , Eos/AGU.  Excerpt: Running Tide is one of many organizations asking whether submerging seaweed could be part of an effective strategy for mitigating climate change. When these algae photosynthesize, they turn carbon dioxide from the upper ocean into biomass.  In some parts  of the ocean, submerging that biomass below thousands of meters of water could lock its carbon away for hundreds or even thousands of years, drawing down levels of carbon in the atmosphere. ...But major questions remain. For example, if growing seaweed depletes the pool of nutrients available for other forms of ocean life, then will it actually increase the ocean’s net carbon storage? What happens to ocean bottom ecosystems if humanity creates giant, underwater seaweed landfills? And how will companies monitor the effects of sending tons of seaweed to a watery grave?.... 

https://www.nytimes.com/2024/01/06/magazine/glacier-engineering-sea-level-rise.html By on Gertner , The New York Times.  Excerpt: ...a glacier on Greenland’s west coast...referred to by its Danish name, Jakobshavn...situated on the edge of Greenland’s massive ice sheet, that moves 30 billion to 50 billion tons of icebergs off the island every year. ...Glaciologists have identified it as one of the fastest-deteriorating glaciers in the world. ...Jakobshavn alone was responsible for 4 percent of the rise in global sea levels during the 20th century. It probably contains enough ice to ultimately push sea levels up at least another foot. ...at the bottom of the bay’s entrance...the warm water flows over a sill, a ridge rising several hundred feet above the ocean floor ...akin to a threshold that crosses the floor of a doorway between two rooms. [British glaciologist John Moore] and his colleague Michael Wolovick published an article that proposed looking into building  a sea ...

https://eos.org/opinions/a-transformative-carbon-sink-in-the-ocean By Doug Reusch ,  Kayleigh Brisard ,  Gil Hamilton  and  Carson Theriault , Eos/AGU/AGU.  Excerpt: Effectively lowering atmospheric carbon levels will require a range of actions, from  individuals making hard decisions  about lifestyle changes to international cooperation to pursue solutions from a diverse menu of options. Among the options under consideration are methods for  deliberate carbon dioxide removal  (CDR) from the atmosphere.... ...humanity may need to implement CDR on a vast scale to compensate for the extraction and combustion of fossil fuels over the past century.  Ocean alkalinity enhancement  (OAE), in which the addition of ions like Mg 2+  and Ca 2+  (sourced from materials such as olivine or lime) to the ocean drives more dissolution of atmospheric CO 2  to form bicarbonate (HCO 3 – ), holds considerable promise, because the ocean’s ...

https://www.science.org/content/article/changing-clouds-unforeseen-test-geoengineering-fueling-record-ocean-warmth By Paul Voosen, Science.  Excerpt: ...Regulations imposed in 2020 by the United Nations’s International Maritime Organization (IMO) have cut ships’ sulfur pollution by more than 80% and improved air quality worldwide. The reduction has also lessened the effect of sulfate particles in seeding and brightening the distinctive low-lying, reflective clouds that follow in the wake of ships and help cool the planet. The 2020 IMO rule “is a big natural experiment,” says Duncan Watson-Parris, an atmospheric physicist at the Scripps Institution of Oceanography. “We’re changing the clouds.” By dramatically reducing the number of ship tracks, the planet has warmed up faster, several new studies have found. That trend is magnified in the Atlantic, where maritime traffic is particularly dense. In the shipping corridors, the increased light represents a 50% boost to the warming effec...

https://www.science.org/content/article/could-solar-geoengineering-cool-planet-u-s-gets-serious-about-finding-out By Paul Voosen, Science.  Excerpt: Any work on solar geoengineering—the notion of artificially making the atmosphere more reflective to cool an overheated planet—is fraught with controversy. ...The U.S. National Oceanic and Atmospheric Administration (NOAA) is venturing ...to understand the types, amounts, and behavior of particles naturally present in the stratosphere. ...Research on solar geoengineering—also called solar radiation management—has long been anathema to some climate scientists and activists. They fear it could distract from emissions cuts, could have unforeseen risks, and would not address some impacts of rising carbon dioxide, including ocean acidification. Federal agencies have largely steered clear of the work, even after a report from the National Academies of Sciences, Engineering, and Medicine (NASEM) in 2021  recommended a $200 million r...

https://www.science.org/content/article/ocean-geoengineering-scheme-aces-its-first-field-test By Paul Voosen, Science.  Excerpt: Alkaline lime powder spread in Florida estuary drew down carbon and reduced acidification. The balmy, shallow waters of Apalachicola Bay, off Florida’s panhandle, supply about 10% of U.S. oysters. But the industry has declined in recent years, in part because the bay is warming and its waters are acidifying because of rising carbon dioxide (CO 2 ) levels. ...state officials encouraged climate scientists to perform an unusual experiment to see whether they could reverse the changes in the water. In May, at an Apalachicola estuary, the researchers injected some 2000 liters of seawater enriched with lime, an alkaline powder and a primary ingredient in cement that’s derived from chalk or limestone. They showed it neutralized some of the acidity and, in the process, drew CO 2  out of the atmosphere. ...as CO 2  continues to rise and geoengineering a ...

https://www.nytimes.com/2021/10/01/opinion/climate-change-geoengineering.html Source: By David Keith, The New York Times.  Excerpt: [We usually do not post opinion pieces, but this one raises an important point...] ...Warming is proportional to the cumulative emissions over the industrial era. Eliminating emissions by about 2050 is a difficult but achievable goal. ...Average temperatures will stop increasing when emissions stop, but cooling will take thousands of years as greenhouse gases slowly dissipate from the atmosphere. Because the world will be a lot hotter by the time emissions reach zero, heat waves and storms will be worse than they are today. And while the heat will stop getting worse, sea level will continue to rise for centuries as polar ice melts in a warmer world. This July was the  hottest month ever recorded , but it is likely to be one of the coolest Julys for centuries after emissions reach zero. ...To cool the planet in this century, humans must either remo...