Oceans losing oxygen at unprecedented rate, experts warn

Oceans losing oxygen at unprecedented rate, experts warn

SOURCE: The Guardian DATE: December 7, 2019 SNIP: Oxygen in the oceans is being lost at an unprecedented rate, with “dead zones” proliferating and hundreds more areas showing oxygen dangerously depleted, as a result of the climate emergency and intensive farming, experts have warned. Sharks, tuna, marlin and other large fish species were at particular risk, scientists said, with many vital ecosystems in danger of collapse. Dead zones – where oxygen is effectively absent – have quadrupled in extent in the last half-century, and there are also at least 700 areas where oxygen is at dangerously low levels, up from 45 when research was undertaken in the 1960s. All fish need dissolved oxygen, but the biggest species are particularly vulnerable to depleted oxygen levels because they need much more to survive. Evidence shows that depleted levels are forcing them to move towards the surface and to shallow areas of sea, where they are more vulnerable to fishing. Some ocean areas are naturally lower in oxygen than others, but these are even more susceptible to damage when their oxygen levels are depleted further, the report’s authors said. Species that can more easily tolerate low oxygen levels, such as jellyfish, some squid and marine microbes, can flourish at the expense of fish, upsetting the balance of ecosystems. The natural oceanic cycles of phosphorus and nitrogen are also at risk. The world’s oceans are already being overfished, and assailed by a rising tide of plastic waste, as well as other pollutants. Seas are about 26% more acidic than in pre-industrial times because of absorbing the excess carbon dioxide in the atmosphere, according...
Rising Seas Aren’t Even the Scariest Part of Climate Change in the Oceans

Rising Seas Aren’t Even the Scariest Part of Climate Change in the Oceans

SOURCE: Mother Jones DATE: September 25, 2019 SNIP: Climate change has already taken an irreversible toll on our oceans and frozen places, warns a major new report from the United Nations’ Intergovernmental Panel on Climate Change. Much of the carbon pollution we’ve pumped into the air has gone directly into the world’s seas: They have absorbed 90 percent of the excess heat from the atmosphere, warming without pause for the past 50 years. Because oceans are so unfathomably big and complex—covering two-thirds of Earth’s surface—that warming has consequences for the entire planet. The IPCC Special Report on Ocean and Cryosphere In A Changing Climate is a collaboration among 130 scientists around the world who have assembled data from more than 7,000 papers. The new report manages to paint an even bleaker picture, showing that the oceans have been expanding, acidifying, and losing oxygen at an accelerated rate. One major takeaway from the report: The seas are rising twice as fast as twentieth century averages. The ocean is also heating up twice as fast, absorbing more carbon and acidifying. “The rate of climate change has actually gone up,” lead author of the report’s chapter on oceans, Nate Bindoff of the University of Tasmania, said in a call with reporters. This acceleration of warming and acidification means a cascade of impacts on weather and marine life, such as coral reefs, some of which we still don’t fully understand. The IPCC looks at a range of possible climate-change scenarios, from unabated pollution to dramatic reforms in the next decade. Right now, though, the world is on the most dangerous warming path. Our...
Choices made now are critical for the future of our ocean and cryosphere

Choices made now are critical for the future of our ocean and cryosphere

SOURCE: IPCC DATE: September 25, 2019 SNIP: The latest Intergovernmental Panel on Climate Change (IPCC) Special Report highlights the urgency of prioritizing timely, ambitious and coordinated action to address unprecedented and enduring changes in the ocean and cryosphere. Global warming has already reached 1°C above the pre-industrial level, due to past and current greenhouse gas emissions. There is overwhelming evidence that this is resulting in profound consequences for ecosystems and people. The ocean is warmer, more acidic and less productive. Melting glaciers and ice sheets are causing sea level rise, and coastal extreme events are becoming more severe. People in mountain regions are increasingly exposed to hazards and changes in water availability, the report said. Glaciers, snow, ice and permafrost are declining and will continue to do so. This is projected to increase hazards for people, for example through landslides, avalanches, rockfalls and floods. Smaller glaciers found for example in Europe, eastern Africa, the tropical Andes and Indonesia are projected to lose more than 80% of their current ice mass by 2100 under high emission scenarios. Glaciers and ice sheets in polar and mountain regions are losing mass, contributing to an increasing rate of sea level rise, together with expansion of the warmer ocean. While sea level has risen globally by around 15 cm during the 20th century, it is currently rising more than twice as fast – 3.6 mm per year – and accelerating, the report showed. Sea level will continue to rise for centuries. It could reach around 30-60 cm by 2100 even if greenhouse gas emissions are sharply reduced and global warming is limited to well...
Why Restaurant Demand For Smaller Fish Fillets Is Bad News For Oceans

Why Restaurant Demand For Smaller Fish Fillets Is Bad News For Oceans

SOURCE: OPB DATE: March 19, 2019 SNIP: For certain snappers, a market preference for plate-size whole fillets is driving fishermen to target smaller fish. For some wild fish populations, this is a recipe for collapse. “The preferred size of a fillet in the U.S. market corresponds to juvenile fish that haven’t had a chance to reproduce,” says conservation biologist Peter Mous, director of the Nature Conservancy’s Indonesia Fisheries Conservation Program. “A lot of species here are heavily overfished, and this demand for small fillets is making things worse.” The reproductive patterns and growth rates of these fish vary widely, but with virtually all species, the market prefers what are essentially baby fish. He says many snapper species have already been depleted to an estimated 10 percent of their unfished biomass — a term that refers to a population’s total mass, rather than the number of individuals. The demand for smaller fish seems to be coming mainly from the American retail and restaurant market, where many chefs and large-scale caterers tend to prefer not only whole intact fillets, but fillets that, on their own, perfectly constitute a single...
Heatwaves sweeping oceans ‘like wildfires’, scientists reveal

Heatwaves sweeping oceans ‘like wildfires’, scientists reveal

SOURCE: The Guardian DATE: March 4, 2019 SNIP: The number of heatwaves affecting the planet’s oceans has increased sharply, scientists have revealed, killing swathes of sea-life like “wildfires that take out huge areas of forest”. Global warming is gradually increasing the average temperature of the oceans, but the new research is the first systematic global analysis of ocean heatwaves, when temperatures reach extremes for five days or more. The research found heatwaves are becoming more frequent, prolonged and severe, with the number of heatwave days tripling in the last couple of years studied. In the longer term, the number of heatwave days jumped by more than 50% in the 30 years to 2016, compared with the period of 1925 to 1954. As heatwaves have increased, kelp forests, seagrass meadows and coral reefs have been lost. These foundation species are critical to life in the ocean. They provide shelter and food to many others, but have been hit on coasts from California to Australia to...