The ‘great dying’: rapid warming caused largest extinction event ever

The ‘great dying’: rapid warming caused largest extinction event ever

SOURCE: The Guardian DATE: December 6, 2018 SNIP: Rapid global warming caused the largest extinction event in the Earth’s history, which wiped out the vast majority of marine and terrestrial animals on the planet, scientists have found. The Permian mass extinction, known as the “great dying”, occurred around 252m years ago and marked the end of the Permian geologic period. The study of sediments and fossilized creatures show the event was the single greatest calamity ever to befall life on Earth, eclipsing even the extinction of the dinosaurs 65m years ago. Up to 96% of all marine species perished while more than two-thirds of terrestrial species disappeared. The cataclysm was so severe it wiped out most of the planet’s trees, insects, plants, lizards and even microbes. The great dying event, which occurred over an uncertain timeframe of possibly hundreds of years, saw Earth’s temperatures increase by around 10C (18F). Oceans lost around 80% of their oxygen, with parts of the seafloor becoming completely oxygen-free. Scientists believe this warming was caused by a huge spike in greenhouse gas emissions, potentially caused by volcanic activity. “It does terrify me to think we are on a trajectory similar to the Permian because we really don’t want to be on that trajectory,” Stanford University scientist Jonathan Payne said. “It doesn’t look like we will warm by around 10C and we haven’t lost that amount of biodiversity yet. But even getting halfway there would be something to be very concerned about. The magnitude of change we are currently experiencing is fairly large.” Curtis Deutsch, an oceanography expert at University of Washington said: “We are...
As North Sea Oil Wanes, Removing Abandoned Rigs Stirs Controversy

As North Sea Oil Wanes, Removing Abandoned Rigs Stirs Controversy

SOURCE: Yale E360 DATE: June 26, 2018 SNIP: Two decades ago, the North Sea was one of the world’s largest sources of oil, pumping up 6 million barrels a day. That figure is now down to 1.5 million barrels, and the industry is turning to the task of decommissioning the estimated 600 production platforms in the North Sea. The British sector alone contains 470 of them, along with roughly as many other offshore installations, plus 10,000 kilometers of pipelines and 5,000 wells. The British industry expects to carry out more than 200 decommissions between now and 2025. Many steel rigs will be cut off just below the seabed, and either dragged ashore in one piece or dismantled offshore. A handful of early giant concrete structures, which can weigh as much as 400,000 tons, may have to stay put because there is no way of moving them. The British industry estimates the final bill at $51 billion, though some analysts say it will be double that. Whatever the price, since decommissioning is tax deductible, the cost will be largely born by taxpayers. Are they getting value for their cleanup cash? Will the expenditure even be good for the environment? Some ecologists say no on both counts. [T]here has been a growing debate among marine scientists about whether the cleanup may sometimes do more harm than good. For during their lives of 30-40 years, many of the rigs have turned into valuable marine habitats, providing rare hard structures in a sea whose bed is mostly soft sand and mud. They are surrogate reefs, often occupied by rare species. Linked by ocean...
When Tropical Cyclones Can’t Move On

When Tropical Cyclones Can’t Move On

SOURCE: National Center for Environmental Information at NOAA DATE: June 6, 2018 SNIP: Tropical cyclones—also sometimes referred to as hurricanes and typhoons—are taking substantially longer to move from place to place, according to a new study by NCEI scientist Jim Kossin. In his paper, “A Global Slowdown of Tropical Cyclone Translation Speed (link is external),” published in Nature, Kossin demonstrates that, globally, tropical cyclones slowed by 10 percent between 1949 and 2016. With additional water vapor in the atmosphere in a warming world, as little as a 10 percent slowdown could double local rainfall and flooding impacts caused by 1°C of warming. According to the study, tropical cyclones have slowed in both hemispheres and in every ocean basin except the Northern Indian Ocean. But, tropical cyclones have generally slowed more in the Northern Hemisphere, where more of these storms typically occur each year. “Of great importance to society,” says Kossin, “tropical cyclones over land have slowed down 20 percent in the Atlantic, 30 percent in the western North Pacific, and 19 percent in the Australian region. These trends are almost certainly increasing local rainfall totals and freshwater flooding, which is associated with very high mortality risk.” Hurricane Harvey in 2017 serves as a dramatic example of the consequences a slow-moving or “stalled” tropical cyclone can produce. Harvey—the hurricane that refused to leave—dumped upwards of 50 inches of rain on Houston, Texas, and the surrounding area in just five days. Some locations received two feet of rain in just two days. [Slower than expected?...
The Ocean Is Losing Its Breath

The Ocean Is Losing Its Breath

SOURCE: Scripps Institution of Oceanography DATE: January 4, 2018 SNIP: In the past 50 years, the amount of water in the open ocean with zero oxygen has gone up more than fourfold. In coastal water bodies, including estuaries and seas, low-oxygen sites have increased more than 10-fold since 1950. Scientists expect oxygen to continue dropping even outside these zones as Earth warms. To halt the decline, the world needs to rein in both climate change and nutrient pollution, an international team of scientists including Lisa Levin, a biological oceanographer at Scripps Institution of Oceanography at the University of California San Diego, asserted in a new paper published Jan. 4 in Science. In areas traditionally called “dead zones,” like those in Chesapeake Bay and the Gulf of Mexico, oxygen plummets to levels so low many animals suffocate and die. As fish avoid these zones, their habitats shrink and they become more vulnerable to predators or fishing. But the problem goes far beyond “dead zones,” the authors point out. Even smaller oxygen declines can stunt growth in animals, hinder reproduction and lead to disease or even death. It also can trigger the release of dangerous chemicals such as nitrous oxide, a greenhouse gas up to 300 times more powerful than carbon dioxide, and toxic hydrogen sulfide. While some animals can thrive in dead zones, overall biodiversity falls. Climate change is the key culprit in the open ocean. Warming surface waters make it harder for oxygen to reach the ocean interior. Furthermore, as the ocean as a whole gets warmer, it holds less oxygen. In coastal waters, excess nutrient pollution from land...
The Bottom of the Ocean Is Sinking

The Bottom of the Ocean Is Sinking

SOURCE: LiveScience DATE: January 4, 2018 SNIP: The bottom of the ocean is more of a “sunken place” than it used to be. In recent decades, melting ice sheets and glaciers driven by climate change are swelling Earth’s oceans. And along with all that water comes an unexpected consequence — the weight of the additional liquid is pressing down on the seafloor, causing it to sink. Consequently, measurements and predictions of sea-level rise may have been incorrect since 1993, underestimating the growing volume of water in the oceans due to the receding bottom, according to a new study. [Scientists] found that around the world for two decades, ocean basins deformed an average of 0.004 inches (0.1 millimeter) per year, with a total deformation of 0.08 inches (2 mm). However, there were distinct regional patterns to the seafloor’s bending and stretching, and the amount of sag in certain parts of the ocean bottom could be significantly higher — as much as 0.04 inches (1 mm) per year in the Arctic Ocean, for a total of 0.8 inches (20 mm), the study authors reported. As a result, satellite assessments of sea-level change — which don’t account for a sinking ocean bottom — could be underestimating the amount that seas are rising by 8 percent, according to the...