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      Even the sea has light pollution. These new maps show its extent

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      The first global atlas of ocean light pollution shows that large swaths of the sea are squinting in the glare of humans’ artificial lights at night.

      From urbanized coastlines along the Persian Gulf to offshore oil complexes in the North Sea, humans’ afterglow is powerful enough to penetrate deep into many coastal waters, potentially changing the behaviors of creatures that live there, researchers report December 13 in Elementa: Science of the Anthropocene. Regional and seasonal differences — such as phytoplankton blooms or sediment from rivers — also affect the depth to which light penetrates.

      Artificial lights are known to affect land dwellers, such as by swelling or shrinking certain insect populations, or by making it harder for sparrows to fight off West Nile virus (SN: 3/30/21; SN: 8/31/21; SN: 1/19/18). But the bright lights of coastal cities, oil rigs and other offshore structures can also create a powerful glow in the sky over the sea.

      To assess where this glow is strongest, marine biogeochemist Tim Smyth of Plymouth Marine Laboratory in England and colleagues combined a world atlas of artificial night sky brightness created in 2016 with ocean and atmosphere data (SN: 6/10/16). Those data include shipboard measurements of artificial light, satellite data collected monthly from 1998 to 2017 to estimate the prevalence of light-scattering phytoplankton and sediment, and computer simulations of how different wavelengths of light move through the water.

      Not all species are equally sensitive to light, so to assess impact, the team focused on copepods, ubiquitous shrimplike creatures that are a key part of many ocean food webs. Like other tiny zooplankton, copepods use the sun or the winter moon as a cue to plunge en masse to the dark deep, seeking safety from surface predators (SN: 1/11/16; SN: 4/18/18).

      Humans’ nighttime light has the most impact in the top meter of the water, the team found. Here, artificial light is intense enough to cause a biological response across nearly 2 million square kilometers of ocean, an area roughly that of Mexico. Twenty meters down, the total affected area shrinks by more than half to 840,000 square kilometers.

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      Some deep-sea octopuses aren’t the long-haul moms scientists thought they were

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      Octopuses living in the deep sea off the coast of California are breeding far faster than expected.

      The animals lay their eggs near geothermal springs, and the warmer water speeds up embryonic development, researchers report February 28 at the virtual 2022 Ocean Sciences Meeting. That reproductive sleight of hand means that the octopus moms brood for less than two years, instead of the estimated 12.

      In 2018, scientists working off the coast of California discovered thousands of deep-sea octopuses (Muusoctopus robustus) congregated on a patch of seafloor about 3,200 meters below the surface. Many of the grapefruit-sized animals were females brooding clutches of eggs, leading researchers to dub the site the Octopus Garden.

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      But with water temperatures hovering around a frigid 1.6° Celsius, growth in this garden was predicted to be leisurely. In octopuses, embryonic development tends to slow down at low temperatures, says marine ecologist Jim Barry of the Monterey Bay Aquarium Research Institute in Moss Landing, Calif. “When you get really cold, down near zero, that’s when brood periods get really long.”

      The record for the longest brood period of any animal, just over four years, is held by a different species of octopus living in warmer water (SN: 7/30/14). M. robustus, thriving in the chilly depths of the Octopus Garden, was therefore a serious contender to snatch that title, Barry says. “If you look at its predicted brood period at 1.6° C, it’s over 12 years.”

      To verify what would be a record-setting stint of motherhood, Barry and his colleagues repeatedly visited the Octopus Garden from 2019 to 2021 using a remotely operated vehicle. The team trained cameras at the octopus eggs, which resemble white fingers, to monitor their rate of development. With one of the submersible’s robotic arms, the researchers also gently nudged dozens of octopuses aside and measured the water temperature in their nests.

      The team found that relatively warm water — up to 10.5° C — bathed all the egg clutches. The female octopuses are preferentially laying their eggs in streams of geothermally heated water, the researchers realized. That discovery was a tip-off that these animals are not the long-haul moms people thought them to be, Barry says. “We’re virtually certain these animals are breeding far more rapidly than you’d expect.”

      Deep-sea octopuses (Muusoctopus robustus) brood clutches of eggs, which look like white fingers.Ocean Exploration Trust, NOAA

      Based on observations of the developing eggs, Barry and colleagues calculated that the moms brooded for only about 600 days, or about a year and a half. That is much faster than predicted, says Jeffrey Drazen, a deep-sea ecologist at the University of Hawaii at Manoa who was not involved in the research. “They’re cutting a huge amount of time off of their parental care period.”

      There is also an evolutionary advantage to seeking out warmer water: Shorter brood periods mean that fewer eggs are likely to be gobbled up by predators. And these octopuses seem to know that, Barry says. “We believe they’re exploiting that thermal energy to improve reproductive success.”

      Only a few other marine animals, such as icefish in Antarctica’s Weddell Sea (SN: 1/13/22), are known to seek out warmer conditions when breeding. But there are probably other species that do the same, Drazen says. The challenge is finding them and their breeding grounds in the vast expanse of the deep ocean. “I imagine that as we keep looking, we will keep finding really interesting sites that are important to certain species,” he says. More

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      A UN report shows climate change’s escalating toll on people and nature

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      Neither adaptation by humankind nor mitigation alone is enough to reduce the risk from climate impacts, hundreds of the world’s scientists say. Nothing less than a concerted, global effort to both drastically curb carbon emissions and proactively adapt to climate change can stave off the most disastrous consequences, according to the latest report from the United Nations’ Intergovernmental Panel on Climate Change, or IPCC.

      That dire warning comes as the effects of climate change on people and nature are playing out across the globe in a more widespread and severe manner than previously anticipated. And the most vulnerable communities — often low-income or Indigenous — are being hit the hardest, the report says.

      “It’s the strongest rebuttal that we’ve seen yet of this idea that we can just adapt our way out of climate change and we don’t have to mitigate emissions,” says Anne Christianson, the director of international climate policy at the Center for American Progress in Washington, D.C., who was not involved in the report.

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      A consortium of 270 scientists from 67 countries synthesized the report after reviewing over 34,000 studies. Released February 28 as part of the IPCC’s sixth assessment of climate science, the report details how the impacts of climate change are playing out today in different regions, and assessed the capacities of communities and regions to adapt.

      Many countries understand the need for climate adaptation. And modern solutions, such as the building of urban gardens or adoption of agroforestry, where implemented, appear to show promise. But, the report finds, efforts to adapt are, by and large, reactionary, small and drastically underfunded. As a result, about 3.3 billion to 3.6 billion people remain highly vulnerable to climate risks such as extreme weather events, sea level rise and food and water shortages. The need for adaptation is greatest — and growing larger — in low-income regions, most notably in parts of Africa, South Asia, small island states and Central and South America.

      The report also underscores the importance of involving those who are impacted the most in climate plans. “We can no longer just make these decisions at the highest level; we need to include local stakeholders, Indigenous groups, local communities and those who are most as at risk for climate change, such as women, racial minorities, the elderly and children,” Christianson says.

      Last August, a previous report, also part of the IPCC’s sixth assessment, covered the physical science underpinning climate change (SN: 8/9/21). In that report, scientists stated loud and clear that there was no time to waste. By 2030, carbon emissions need to be cut in half, compared with 2017 levels, to prevent global temperatures from climbing 1.5° Celsius above the preindustrial baseline, the report found. Beyond that baseline, the capacity for humankind and nature to adapt severely deteriorates. In a bit of good news, the authors of that 2021 report also found that if all carbon emissions were to cease today, global temperatures would stop rising in about three years, not the 30 to 40 years once thought. In other words, we can make a big difference in very little time.

      Still, climate change is already affecting many parts of Earth. And some of the consequences aren’t going away anytime soon. Sea level will continue to rise for decades, driven in part by the runaway melting of Greenland’s ice sheet (SN: 9/30/20). By 2050, sea level along U.S. coastlines will have risen by 25 to 30 centimeters, or roughly one foot, the National Oceanic and Atmospheric Administration estimates.

      The latest IPCC report reveals that the effects of climate change, which include an increased frequency of wildfires (such as these in Turkey), are more widespread and severe than had been expected.YASIN AKGUL/AFP via Getty Images

      Extreme weather events and climate-fueled wildfires have already caused mass mortalities of corals and other animals and trees, and pushed entire species toward the brink of extinction (SN: 3/9/21). What’s more, climate change is forcing many people to relocate, as well as detrimentally affecting mental health and spreading disease as vectors such as mosquitoes shift to new habitats (SN: 5/12/20; SN: 10/7/19).

      Adaptation is especially needed in cities, which are growing and expected to contain two-thirds of the world’s population by 2050, including climate refugees from elsewhere, the new report finds. Urban communities are becoming increasingly vulnerable to extreme heat waves, urban heat island effects, floods and storm surges (SN: 9/18/21).

      Outside of cities, the breakdown of ecosystems and loss of biodiversity severely impacts the people who rely on natural systems for their livelihoods, the report emphasizes. Farmers in the global south are finding it increasingly challenging to grow crops as a result of droughts, heat waves, floods and sea-level rise (SN: 9/24/21). People who make their living fishing are being forced to travel greater distances to pursue species that are altering their natural ranges as ocean temperatures warm.

      Key to adapting to these impacts is the restoration and preservation of natural ecosystems, the report states. Conserving 30 to 50 percent of the planet’s land, ocean and freshwater ecosystems will help support biodiversity and enhance climate resilience (SN: 4/22/20). Preserving mangrove forests, for instance, along less developed coastlines sequesters large amounts of carbon and protects against storm surges (SN:5/7/21, SN: 6/4/20).

      “The truth is that nature can be our savior,” said Inger Andersen, executive director of the U.N. Environment Programme, at a February 28 news conference announcing the report’s release. “But only if we save it first.”

      Still, the natural world and many of the “services” it provides to humankind, such as carbon storage and flood control, begin to break down more rapidly at about 1.5° C above preindustrial temperatures, the report notes. And the window to prevent that from happening is closing. “We are on a trajectory to losing many of these systems and the services they provide” says Borja Reguero, a coastal science researcher at the University of California, Santa Cruz who reviewed the report.

      What that means is there is no time to waste. “We simultaneously need to reduce our greenhouse gas emissions, adapt to reduce the risks of climate change and also address losses and damages that are already being experienced,” Adelle Thomas, a climate scientist at the University of the Bahamas in Nassau, said at a February 27 news briefing. Thomas is the lead author of the new report’s chapter on key risks across sectors and regions.

      “And we have a very limited amount of time left to do this,” she stressed. More

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      Sunlight helps clean up oil spills in the ocean more than previously thought

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      Sunlight may have helped remove as much as 17 percent of the oil slicking the surface of the Gulf of Mexico following the 2010 Deepwater Horizon spill. That means that sunlight plays a bigger role in cleaning up such spills than previously thought, researchers suggest February 16 in Science Advances.

      When sunlight shines on spilled oil in the sea, it can kick off a chain of chemical reactions, transforming the oil into new compounds (SN: 6/12/18). Some of these reactions can increase how easily the oil dissolves in water, called photodissolution. But there has been little data on how much of the oil becomes water-soluble.

      To assess this, environmental chemists Danielle Haas Freeman and Collin Ward, both of Woods Hole Oceanographic Institution in Massachusetts, placed samples of the Macondo oil from the Deepwater Horizon spill on glass disks and irradiated them with light using LEDs that emit wavelengths found in sunlight. The duo then chemically analyzed the irradiated oil to see how much was transformed into dissolved organic carbon.

      The most important factors in photodissolution, the researchers found, were the thickness of the slick and the wavelengths of light. Longer wavelengths (toward the red end of the spectrum) dissolved less oil, possibly because they are more easily scattered by water, than shorter wavelengths. How long the oil was exposed to light was not as important.

      Though the team didn’t specifically test for seasonal or latitude differences, computer simulations based on the lab data suggested that those factors, as well as the oil’s chemical makeup, also matter.

      The researchers estimate irradiation helped dissolve from 3 to 17 percent of surface oil from the Deepwater Horizon spill, comparable to processes such as evaporation and stranding on coastlines. What impact the sunlight-produced compounds might have on marine ecosystems, however, isn’t yet known.  More

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      Freshwater ice can melt into scallops and spikes

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      Water’s wacky density leads to strange effects that researchers are still uncovering.

      Typically, liquids become denser the more they cool. But freshwater is densest at 4° Celsius. As it cools below that temperature, the water becomes less dense and rises. As a result, ice columns submerged in liquid water can melt into three different shapes, depending on the water’s temperature, researchers report in the Jan. 28 Physical Review Letters.  

      “Almost everything” about the findings was surprising, says mathematician Leif Ristroph of New York University.

      Ristroph and colleagues anchored ultrapure ice cylinders up to 30 centimeters long in place and submerged them in tanks of water at temperatures from 2° to 10° C.

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      The ice melted into smooth, downward-pointing spikes if placed in water lower than about 5° C. Simulations showed “a strange thing — that the cold liquid water near the ice is actually buoyant” due to being less dense than the rest of the water in the tank, Ristroph says. So that upward flow draws warmer water closer to the ice’s base, causing it to melt faster than the top.  

      The opposite occurred above about 7° C; the ice formed an upward-pointing spike. That’s because colder water near the ice is denser than the surrounding water and sinks, pulling in warmer water at the top of the ice and causing it to melt faster than the bottom, simulations showed. This matches “what your intuition would expect,” Ristroph says. 

      Between about 5° to 7° C, the ice melted into scalloped columns. “Basically, the water is confused,” Ristroph says, so it forms different layers, some of which tend to rise and others which tend to sink, depending on their density. Ultimately, the water organizes into “swirls or vortices of fluid that carve the weird ripples into the ice.”

      More work is needed to understand the complex interplay of factors that may generate these and other shapes on ice melting in nature (SN: 4/9/21). More

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      Deep-sea Arctic sponges feed on fossilized organisms to survive

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      In the cold, dark depths of the Arctic Ocean, a feast of the dead is under way.

      A vast community of sponges, the densest group of these animals found in the Arctic, is consuming the remains of an ancient ecosystem to survive, researchers report February 8 in Nature Communications.

      The study highlights just how opportunistic sponges are, says Jasper de Goeij, a deep-sea ecologist at the University of Amsterdam not involved with this work. Evolutionarily speaking, sponges “are more than 600 million years old, and they inhabit all parts of our globe,” he says. Scientists might not know about all of them because many places that sponges inhabit are really difficult to get to, he adds.

      Sponges are predominantly filter feeders, and are crucial to nutrient recycling throughout the oceans. The existence of this colony, discovered by a research ship in 2016, however, has been an enigma.

      The sponges, which include the species Geodia parva, G. hentscheli and Stelletta rhaphidiophora, live between 700 and 1,000 meters down in the central Arctic Ocean, where there are virtually no currents to provide food, and sea ice covers the water year-round. What’s more, sponges are largely immobile, yet in 2021 researchers, including Teresa Morganti, a marine biologist at the Max Planck Institute for Marine Microbiology in Bremen, Germany, reported that these ones slowly move, using their spicules — microscopic skeletal structures — and leaving them as thick brown trails in their wake.

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      In the new study, Morganti and colleagues turned their attention to the matted layer underneath the sponge colony, a smorgasbord of discarded spicules and blackened fossilized life, including empty worm tubes and mollusk shells. To see if this thick mat was a food source, the team analyzed samples of the sponges, the mat material and the surrounding water. The researchers also investigated the genetic makeup of the microbes that live within the sponge tissues, and those in the sediment.

      Carbon and nitrogen isotopes — atoms with different numbers of neutrons — in the sponge tissues closely matched those of the dead matter below, suggesting the animals were consuming it. The genetic signature of the microbes showed they had enzymes capable of breaking down the material and were likely dissolving the dead organic matter into food for the sponges (SN: 12/27/13).

      The matted layer is up to 15 centimeters thick in places, the researchers found. Assuming that the layer is, on average, greater than 4 centimeters thick, it could provide almost five times the carbon that the sponges would need to survive, the team calculates.

      The discovery that the sponges are feeding from below means they are likely moving to access more food, Morganti and colleagues suggest. The scientists also found many sponges to be budding, or breaking off parts to form new individuals, showing active reproduction.

      Radiocarbon dating showed the adult sponges — spread across more than 15 square kilometers on the peaks of an underwater volcanic mountain range — to be over 300 years old on average, a “truly outstanding” finding, says Paco Cardenas, a sponge expert at Uppsala University in Sweden who was not involved with the new study. “We expected sponges to grow very slowly, but this had never been measured in the deep sea,” he says.          

      The dead ecosystem below the sponges is around 2,000 to 3,000 years older, a once-thriving community of animals that lived in the nutrient-rich conditions created when the volcanoes were last active, the researchers suggest.

      Sponges often appear to take advantage of the most abundant carbon sources, which may change as global warming alters the composition of the oceans, says ecologist Stephanie Archer of the ​​Louisiana Universities Marine Consortium in Chauvin, who was not involved in the work. “One big question will be how flexible sponge-microbe associations are, and how quickly they change to take advantage of shifting carbon sources,” she says. More

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      Satellites have located the world’s methane ‘ultra-emitters’

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      A small number of “ultra-emitters” of methane from oil and gas production contribute as much as 12 percent of emissions of the greenhouse gas to the atmosphere every year — and now scientists know where many of these sources are.

      Analyses of satellite images from 2019 and 2020 reveal that a majority of the 1,800 biggest methane sources come from six major oil- and gas-producing countries: Turkmenistan led the pack, followed by Russia, the United States, Iran, Kazakhstan and Algeria.

      Plugging those leaks would not only be a boon to the planet, but also could save those countries billions in U.S. dollars, climate scientist Thomas Lauvaux of the University of Paris-Saclay and colleagues report in the Feb. 4 Science.

      Ultra-emitters are sources that spurt at least 25 metric tons of methane per hour into the atmosphere. These occasional massive bursts make up only a fraction — but a sizable one — of the methane shunted into Earth’s atmosphere annually.

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      Cleaning up such leaks would be a big first step in reducing overall emissions, says Euan Nisbet, a geochemist at Royal Holloway, University of London in Egham, who was not involved in the study. “If you see somebody badly injured in a road accident, you bandage up the bits that are bleeding hardest.”

      Methane has about 80 times the atmosphere-warming potential of carbon dioxide, though it tends to have a much shorter lifetime in the atmosphere — 10 to 20 years or so, compared with hundreds of years. The greenhouse gas can seep into the atmosphere from both natural and human-made sources (SN: 2/19/20).

      In oil and gas production, massive methane bursts might be the result of accidents or leaky pipelines or other facilities, Lauvaux says. But these leaks are often the result of routine maintenance practices, the team found. Rather than shut down for days to clear gas from pipelines, for example, managers might open valves on both ends of the line, releasing and burning off the gas quickly. That sort of practice stood out starkly in satellite images as “two giant plumes” along a pipeline track, Lauvaux says.

      Stopping such practices and repairing leaky facilities are relatively easy, which is why such changes may be the low-hanging fruit when it comes to addressing greenhouse gas emissions. But identifying the particular sources of those huge methane emissions has been the challenge. Airborne studies can help pinpoint some large sources, such as landfills, dairy farms and oil and gas producers, but such flights are limited by being both regional and of short duration (SN: 11/14/19).

      Satellites, such as the European Space Agency’s Tropospheric Monitoring Instrument, or TROPOMI, offer a much bigger window in both space and time. Scientists have previously used TROPOMI to estimate the overall leakiness of oil and gas production in Texas’s massive Permian Basin, finding that the region sends twice as much methane to the atmosphere as previously thought (SN: 4/22/20).

      In the new study, the team didn’t include sources in the Permian Basin among the ultra-emitters; the large emissions from that region are the result of numerous tightly clustered but smaller emissions sources. Because TROPOMI doesn’t peer well through clouds, other regions around the globe, such as Canada and the equatorial tropics, also weren’t included.

      But that doesn’t mean those regions are off the hook, Lauvaux says. “There’s just no data available.” On the heels of this broad-brush view from TROPOMI, Lauvaux and other scientists are now working to plug those data gaps using other satellites with better resolution and the ability to penetrate clouds.

      Stopping all of these big leaks, which amount to an estimated 8 to 12 percent of total annual methane emissions, could save these countries billions of dollars, the researchers say. And the reduction in those emissions would be about as beneficial to the planet as cutting all emissions from Australia since 2005, or removing 20 million vehicles from the roads for a year.

      Such a global map can also be helpful to countries in meeting their goals under the Global Methane Pledge launched in November at the United Nations’ annual climate summit, says Daniel Jacob, an atmospheric chemist at Harvard University who was not involved in the study (SN: 1/11/22).

      Signatories to the pledge agreed to reduce global emissions of the gas by at least 30 percent relative to 2020 levels by 2030. These new findings, Jacob says, can help achieve that target because it “encourages action rather than despair.”  More