Scientists have good estimates of where the retreating grounding line is, thanks to satellites watching for tiny changes in the ice’s elevation. But they haven’t had a good picture of what the glacier’s belly looks like at the grounding line, because it’s under thousands of feet of ice. “These data are really exciting because we’re getting a look into a hidden system,” says University of Waterloo glaciologist Christine Dow, who studies Antarctic glaciers but wasn’t involved in the research.
Video: ITGC/Schmidt/Washam
With Icefin, the researchers could remotely pilot a camera while measuring the salinity, temperature, and oxygen content of the water. “We saw that the ice base itself was very complex in its topography, so there’s lots of staircases, terraces, rifts, and crevasses,” says British Antarctic Survey physical oceanographer Peter Davis, the lead author of one of the papers and coauthor on the other. “The rate of melting on different surfaces was very different.”
Where the glacier’s underside (or basal ice, in the scientific parlance) is smoother, melting is definitely happening, but at a much slower rate than where the topography is jagged. That’s because a layer of cold water rests where the ice is flat, insulating it from warmer ocean water like a liquid blanket. But where the topography is sloped and irregular, there are more vertical surfaces where warm water can attack the ice, including making incursions from the side. This melting creates a peculiar “scalloped” look, like the surface of a golf ball.
These complex, expanding basal features could then influence the rest of the ice. “If you open up features underneath the ice, you also get similar reflections of them on the surface, because of the way that the ice is floating,” says Davis. “So there’s a fear that if you’re widening these rifts and crevices under the ice, you can destabilize the ice shelf, which could lead to greater disintegration over time.”
This story originally appeared in The Guardian and is part of theClimate Deskcollaboration.
They are gray and rectangular, and if you laid all 2 billion of them together they would cover an area roughly the size Connecticut, about 5,500 square miles. Parking lots have a monotonous ubiquity in US life, but a growing band of cities and states are now refusing to force more on people, arguing that they harm communities and inflame the climate crisis.
For many years, local governments have required the construction of parking lots as part of any development. These measures, along with expansive highways that cut through largely minority neighborhoods and endless suburban sprawl, have cemented cars as the default transportation option for most Americans.
Starting in January, though, California will become the first US state to enact a ban on parking minimums, halting their use in areas with public transport in a move that Governor Gavin Newsom called a “win-win” for reducing planet-heating emissions from cars, as well as helping alleviate the lack of affordable housing in a state that has lagged in building new dwellings.
Several cities across the country are now rushing doing the same, with Anchorage, Alaska; Cambridge, Massachusetts; and Nashville, Tennessee, all recently loosening or scrapping requirements for developers to build new parking lots. “These parking minimums have helped kill cities,” said Gernot Wagner, a climate economist at Columbia Business School who accused political leaders of making downtowns “look like bombs hit them” by filling them with parking lots.
“Getting rid of parking minimums is an amazing step. It’s a piece in the puzzle of climate policy,” said Wagner, who pointed out that transportation is the largest source of planet-heating emissions in the US. “There’s a major rethink going on now, which is good for cities and for families.”
Climate campaigners and public transportation advocates have seized upon the previously esoteric issue of parking minimums, posting aerial pictures on social media demonstrating the vast swathes of prime urban land given over to parking lots and pushing city councils to foster denser communities with more opportunities to walk, cycle, or catch buses and trains rather than simply drive.
Cities such as Buffalo, New York; and Fayetteville, Arkansas, scaled back parking minimums a few years ago and have reported a surge in activity to transform previously derelict buildings into shops, apartments, and restaurants. Developers previously saw such work as unviable due to the requirement to build plots for car parking, in many cases several times larger than the building itself.
Nashville is among a new wave of cities hoping to do the same. “It’s about the climate, it’s about walkability, it’s reducing traffic and the need for everyone to have a car,” said Angie Henderson, a member of the Nashville Metropolitan Council, who proposed the parking change for the city’s core area.
Henderson said she was struck by how a dental practice in her district was forced to construct a parking lot for 45 cars, requiring the clearing of trees from a nearby hillside, despite only having space for a handful of patients.
Berlin, Nevada, is a treasure chest for paleontologists. Just down the road from now-abandoned gold and silver mines, a rockbound collection of bones hints at an even richer past. The Berlin-Ichthyosaur State Park is teeming with dozens of fossils of ancient marine reptiles. That bone bed is so abundant and weird that researchers have been scratching their heads over it for decades.
“There are sites with way more dense occurrences of ichthyosaur skeletons, including places in Chile and Germany,” says Nick Pyenson, curator of fossil marine mammals at the Smithsonian National Museum of Natural History. “But this place, Berlin-Ichthyosaur in eastern Nevada, has really escaped explanation for a long time.” In one particular quarry, at least seven individuals from the genus Shonisaurus—a bloated, bus-sized dolphin with four limb-like flippers—lay essentially stacked atop one another.
Previous hypotheses largely focused on physical or environmental reasons for the cluster of fossils. One suggested that the animals had gotten stranded in shallow water and died as a group some 230 million years ago. Or maybe a volcanic eruption did them in. Pyenson had another hunch, one that his team tested using 3D visualizations of the site, as well as fossils and other clues in the geological record.
Writing in the journal Current Biology, today Pyenson’s team presents evidence that the shonisaurs came there to reproduce. The team concludes that the animals migrated long distances to give birth, like some whales do today. The discovery not only represents an example of “convergent evolution,” in which the same traits independently evolve in different species, but also the oldest example of migration in groups to a designated calving ground.
“They’re making quite a convincing case,” says Lene Liebe Delsett, a vertebrate paleontologist at the University of Oslo, Norway, who was not involved in the study. “Ichthyosaurs were the first large marine tetrapods. And throughout the Triassic, they varied quite a lot, so there was a large diversity. It’s just a very interesting period of time to know more about.”
The origin story of the shonisaurs begins with death—a lot of it.
Some 251 million years ago, between the Permian and Triassic periods, Earth’s biggest extinction event annihilated about 95 percent of all marine species. This so-called “Great Dying” mowed down the diverse landscape of creatures in the ocean.Some of the animals that grew back in their place turned out to be weirder and larger than ever before.
The ensuing Triassic started an evolutionary arms race. Prey evolved harder shells and better mobility, predators crunched through ammonite shells and hunted fish better than ever, and so on. Ichthyosaurs, which evolved from terrestrial reptiles into new species of various sizes, partly drove this pressure and quickly dominated the ocean. The Shonisaurus genus, in particular, grew to be some of the largest marine predators around. “They achieved whale sizes before anything else,” says Pyenson.
Pyenson is normally more of a whale guy; he specializes in mammals, which split from reptiles about 325 million years ago. But ancient marine reptiles like those under the order Ichthyosaur bear many similarities to existing marine mammals. Their ancestors came from land, they birthed live young, they had similar flippers, and they are tetrapods, meaning four-limbed. And Pyenson is well versed in this type of mystery. About a decade ago in Atacama, Chile, he and his South American collaborators used 3D mapping and chemical analyses to show that a tight cluster of at least 40 fossilized whales must have died from a toxic algal bloom 7 to 9 million years ago.
That is, as we polluted less—heavy industry spun down, flights got canceled, people stopped commuting—we also produced less of the pollutant that normally breaks down methane. It’s a second unfortunate and surprising consequence of cutting pollution: Burning fossil fuels also produces aerosols that bounce some of the sun’s energy back into space, somewhat cooling the climate. While it’s imperative that we decarbonize as quickly as possible, cutting out the beneficial effects of NOx and aerosols has some unintended—and twisted—side effects.
“Burning less fossil fuels will cause there to be less OH radicals in the atmosphere, which will cause methane concentrations to go up,” says Earth scientist George Allen of Virginia Polytechnic Institute and State University, who penned an accompanying commentary on the paper but wasn’t involved in the research. “So that’s going to cut back on the effectiveness of measures to fight global warming.”
This makes it all the more urgent for humanity to take drastic steps to reduce both methane and CO2 emissions, especially considering the alarming degradation of northern lands as the planet warms. The growth of emissions from nature also lends more urgency to the fight to preserve those lands. People are, for instance, draining soggy peatlands and setting them on fire to convert them to farmland, which turns them from carbon sinks into carbon sources. And because the Arctic is warming more than four times faster than the rest of the planet, human development can encroach farther north, churning up carbon sequestered in the soil as people build roads and housing. All of that only exacerbates the problem.
That sort of degradation is blurring the line between human sources of methane and natural ones. “While some sectors are clearly anthropogenic—industry, transportation, landfill, and waste—other ‘natural’ sectors such as polluted waterways and wetlands can be low, moderately, or highly impacted by humans, which in turn can enhance ‘natural’ methane emissions,” says Judith Rosentreter, a senior research fellow at Southern Cross University who studies methane emissions but wasn’t involved in the new research.
Meanwhile, the Arctic region is greening, thanks to new vegetation, which darkens the landscape and further warms the soil. Permafrost—which covers 25 percent of the northern hemisphere’s land surface—is thawing so rapidly that it’s gouging holes in the earth, known as thermokarst, which fill with water and provide the ideal conditions for methane-belching microbes.
“There’s a lot of organic carbon locked in there—it’s like a frozen compost heap in your own garden,” says Torsten Sachs of the GFZ German Research Centre for Geosciences, who wasn’t involved in the new research. “There is a lot of talk and a lot of speculation and a lot of modeling of how much greenhouse gasses are going to come out of these thawing and warming permafrost areas. But as long as you don’t have any real on-the-ground data, you can’t really prove it.”
Sachs has been doing exactly that, venturing into the Siberian tundra for months on end to collect data. In a paper he recently published in Nature Climate Change, he found that methane production every June and July has been rising 2 percent per year since 2004. Interestingly, while this corresponds with significantly higher atmospheric temperatures in the region, it doesn’t seem to correspond with permafrost thaw. Instead, the extra methane may come from wetlands sitting on top of permafrost.
This is the extreme complexity scientists are scrambling to better understand. While the new paper’s modeling can tease apart the methane emitted by humans and nature, on-the-ground data is also necessary to fully understand the dynamics. The ultimate concern is that out-of-control carbon emissions could be initiating climatic feedback loops: We burn fossil fuels, which warms the planet, which thaws permafrost and forms bigger methane-emitting wetlands. That will have serious consequences for the rest of the planet.
Scientists can’t yet say, though, whether we’re already witnessing a feedback loop. This new study focused on 2020, so researchers will need to keep collecting methane data for consecutive years and pinpoint the source of those emissions. But methane emissions were even higher in 2021. “The idea that the warming is feeding the warming is definitely something to be concerned about,” says James France, senior international methane scientist at the Environmental Defense Fund. “That is very difficult to mitigate. So it really reinforces the idea that we have to double down and really focus on mitigation on the areas that we can control.”
Clark also found that Americans are moving away from places prone to fleeting heat waves, like the Midwest, yet are flocking to areas with consistently higher summer heat, like the Southwest. In the map above, red is where people have been moving away from places with relatively cool summers or toward areas with relatively hot summers, while blue is the opposite.
These changes could be due to a number of overlapping economic and social factors. “People move away from high unemployment areas—you find those tend to be kind of rural areas with a long history of being economically depressed,” says Clark. “So we have people moving out of areas along the Mississippi River and across the Great Plains and parts of the Midwest and South.” As a result, Americans are generally migrating away from hurricane risk along the Gulf Coast (save for Florida and Texas), and toward the economically booming Northwest, where wildfire risk is high.
And while it’s true that some of the more affluent Americans may be seeking out the beauty of forested areas—especially as the pandemic has allowed more people to work remotely, untethered to a specific city—economic pressure may be forcing others there, too. Skyrocketing housing prices and cost of living are pushing people toward places where homes are cheaper, especially on the expensive West Coast.
“As temperatures increase—as things get drier and hotter and prices for housing get more unaffordable—it’s definitely going to push people into these rural areas,” says Kaitlyn Trudeau, a data analyst at the nonprofit Climate Central who studies wildfires but wasn’t involved in the new study. “Some people don’t have a choice.”
Increases in the number of people living in wildfire zones come at a cost: 2018’s deadly Camp Fire in California alone led to $16.5 billion in losses. And that’s to say nothing of the expense of fighting fires, or preventing them through methods like controlled burns.
There are hidden costs, too, like the health effects of wildfire smoke—even if your house doesn’t burn down, you’re still inhaling nasty particulates and fungi. “I think we’re just starting to quantify and realize how big the smoke effect is,” says University of Wisconsin-Madison forest ecologist Volker Radeloff, who studies the wildland-urban interface but wasn’t involved in the new study. “That makes controlled burns hard, though, because even if the fire is controlled, the smoke can’t be. That’s a real threat to people, especially if they have asthma or other lung illnesses.”
Altogether, the new study shows that Americans are literally moving in the wrong direction. “It’s really hard to see these population booms in these areas,” says Trudeau. “You just can’t help but feel like your stomach sinks a little bit.”
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