Marine heatwave set off ‘carbon bomb’ in world’s largest seagrass meadow

Marine heatwave set off ‘carbon bomb’ in world’s largest seagrass meadow

SOURCE: The Guardian DATE: March 20, 2018 SNIP: A marine heatwave in Western Australia in 2010 set off a massive “carbon bomb”, damaging the world’s largest seagrass meadow, releasing millions of tonnes of carbon that had been collected for thousands of years below the surface. Although Australia doesn’t currently count carbon released from damaged seagrass meadows in its official greenhouse gas emissions, if it did, the results mean those figures might need to be revised upwards by more than 20%. Seagrass is a flowering grass-like plant that grows in shallow waters. It gathers carbon dissolved in the sea and buries it below the surface, often storing similar amounts of carbon in the top metre of sediment as is stored in tropical forests. But unlike forests that store carbon for about 60 years before releasing much of it, seagrass meadows often store the carbon for thousands of years until they are disturbed. That process is thought to offset up to 2% of humanity’s greenhouse gas emissions. Recent studies have shown that when the top layer of actively growing seagrass is disturbed – either by local impacts such as boat anchors or climatic impacts like heatwaves – the carbon that has been sequestered over thousands of years can be quickly released. “It’s a carbon bomb,” said Gary Kendrick, a co-author on the paper from the University of Western Australia. “And it’s one that has gone off without documentation. “If we’re not counting this carbon, then we’re underestimating our...
Climate change, sewage and fertilisers could trigger mass extinction of life in oceans, scientists warn

Climate change, sewage and fertilisers could trigger mass extinction of life in oceans, scientists warn

SOURCE: Independent DATE: Aug 9, 2017 SNIP: The ocean is slowly being suffocated with levels of oxygen falling at a similar rate to 94 million years ago when there was a mass extinction of marine life, scientists have warned. While that event was caused naturally, humans are responsible for several different factors driving the increase in “dead zones” in our seas. Writing in the journal Science Advances, the researchers said that current rates of deoxygenation were similar to those 94 million years ago during what is known as Oceanic Anoxic Event-2 (OAE-2). OAE-2, which developed over about 50,000 years, is believed to have caused the extinction of about 27 per cent of marine invertebrates. One of the researchers, Dr Sune Nielsen, of Woods Hole Oceanographic Institution in the US, said: “Our results show that marine deoxygenation rates prior to the ancient event were likely occurring over tens of thousands of years, and surprisingly similar to the two per cent oxygen depletion trend we’re seeing induced by anthropogenic activity over the last 50 years. “We don’t know if the ocean is headed toward another global anoxic event, but the trend is, of course,...

Plastic Garbage Patch Bigger Than Mexico Found in Pacific

SOURCE: National Geographic DATE: July 25, 2017 SNIP: Yet another floating mass of microscopic plastic has been discovered in the ocean, and it is mind-blowingly vast. A new discovery of a massive amount of plastic floating in the South Pacific is yet another piece of bad news in the fight against ocean plastic pollution. This patch was recently discovered by Captain Charles Moore, founder of the Algalita Research Foundation, a non-profit group dedicated to solving the issue of marine plastic pollution. Moore, who was the first one to discover the famed North Pacific garbage patch in 1997, estimates this zone of plastic pollution could be upwards of a million square miles in size. The term “patch” referring to the plastic pollution in oceanic gyres can be misleading. The pieces of plastic are not necessarily floating bottles, bags, and buoys, but teeny-tiny pieces of plastic resembling confetti, making them almost impossible to clean...
Carbon pollution is suffocating ocean life and speeding up the next mass extinction

Carbon pollution is suffocating ocean life and speeding up the next mass extinction

SOURCE: Think Progress DATE: May 8, 2017 SNIP: Depletion of dissolved oxygen in our oceans, which can cause dead zones, is occurring much faster than expected, a new study finds. And by combining oxygen loss with ever-worsening ocean warming and acidification, humans are re-creating the conditions that led to the worst-ever extinction, which killed over 90 percent of marine life 252 million years ago. Scientists have long predicted that as carbon pollution warms the globe, the amount of oxygen in our oceans would drop, since warmer water can’t hold as much dissolved gas as colder water. But what is especially worrisome about this new research is how quickly it is happening. “The trend of oxygen falling is about two to three times faster than what we predicted from the decrease of solubility associated with the ocean warming,” said lead researcher Prof. Taka Ito. “This is most likely due to the changes in ocean circulation and mixing associated with the heating of the near-surface waters and melting of polar...