10 May 2017, Climate News Network, Ocean oxygen decline greater than predicted. Circulation changes caused by warming waters and melting polar ice are the most probable explanations for the rapidly falling levels of oxygen in the ocean. US scientists who have been warning that warmer oceans are more likely to be poorer in dissolved oxygen have now sounded the alarm: ocean oxygen levels are indeed falling, and seemingly falling faster than the corresponding rise in water temperature. That colder water can hold more dissolved gas than warmer water is a commonplace of physics: it is one reason why polar seas are teeming with marine life and tropical oceans are blue, clear and often relatively impoverished. In 2013, an international consortium of marine scientists warned that oxygen levels in the oceans could fall by between 1% and 7% by the century’s end. And this could, other scientists predicted, lead to what they politely called “respiratory stress” for some marine life. Ocean warming Ocean ecologists in the US and Germany warned last year that parts of the deep oceans were already showing signs of oxygen deprivation with corresponding dead zones. Earlier this year, another research group looked at the computer simulations for the years 1920 to 2100 and predicted that the hazards were likely to increasewith warming. Now the team have returned to the issue. They report in Geophysical Research Letters that they looked at data for the last 50 years and found the oxygen levels started dropping in the 1980s, as ocean temperatures began to climb – and falling unexpectedly rapidly. The trend of oxygen falling is about two to three times faster than what we predicted from the decrease of solubility associated with ocean warming,” says Takamitsu Ito, of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology, who led the study. “This is most likely due to the changes in ocean circulation and mixing associated with the heating of the near-surface waters and the melting of polar ice.” Read More here
Category Archives: Impacts Observed & Projected
6 May 2017, Inside Climate News, Extreme Weather Flooding the Midwest Looks a Lot Like Climate Change. Devastating storms still roiling much of the American Midwest have dumped record levels of rain over the past week and caused flash flooding that has killed at least 10 people, inundated towns and highways, and forced hundreds of people to evacuate their homes. Parts of Missouri, Illinois, Indiana, Arkansas and Louisiana received 10 to 15 inches of rain in the past seven days, according to the National Weather Service, resulting in record crests of numerous rivers across the central United States.Extreme storms like these have become more common as global temperatures have risen and the oceans have warmed. Some have the clear fingerprints of man-made climate change. “Of course there is a climate change connection, because the oceans and sea surface temperatures are higher now because of climate change, and in general that adds 5 to 10 percent to the precipitation,” Kevin Trenberth, a climate scientist with the National Center for Atmospheric Research, said. “There have been many so-called 500-year floods along the Mississippi about every five to 10 years since 1993.” Scientists won’t know the extent to which climate change played a role in these storms unless they do an attribution study. Such analyses determine how much the rise in trapped greenhouse gases increased the odds of a single event happening. Increasingly, scientists have tried to do these studies far more quickly to spread accurate information about how climate change is affecting us today and improve longer-term forecasts and warnings. An attribution study of last August’s deadly Louisiana’s storms—classified as a 1,000-year storm in the worst-hit areas and a 500-year storm in others—found that human-caused climate warming increased the chances of the torrential rains by at least 40 percent. That figure corresponds to the overall increase in extreme storms in the region. “Across the board, the United States has seen an increase in the heaviest rainfall events, and the Midwest specifically has seen an increase [in these events] of almost 40 percent,” said Heidi Cullen, chief scientist at Climate Central and a member of World Weather Attribution (WWA), a group that is developing methods to quickly determine climate change’s role in extreme weather events. Read More here
5 May 2017, Bloomberg Business Week, The Jersey Shore Would Rather Fight Flooding With Walls Than Retreat. The state’s $300 million fund to get coastal homeowners to relocate inland isn’t working. n a recent rainy afternoon near the Jersey Shore, John Spodofora, the mayor of Stafford Township, stood at the edge of the water and pointed to a spot in the salt marsh where he wants to build a giant berm to blunt the force of hurricanes. Stafford is on the western side of Barnegat Bay, the 40-mile body of brackish water north of Atlantic City that’s surrounded by blue-collar bungalows, cheap motels, and oceanfront mansions. In 2012, Stafford took a direct hit from Hurricane Sandy, which destroyed 3,000 of its homes. Rather than leave, most residents chose to rebuild. The berm project would cost as much as $100 million, money the town doesn’t have. Spodofora is hoping the federal or state government will fund it, even though most of the 5,000 homes the berm would protect will likely be underwater in a few decades with or without it. Still, Spodofora is committed. “There’s no areas of my town that I can say aren’t worth protecting,” he says. In coastal New Jersey, the debate about whether the climate is changing has been superseded by a more urgent question: What to do about it? While local officials such as Spodofora want to build walls against rising seas and fiercer storms, environmentalists say that delays the inevitable. The best policy, they say, is to encourage people to move inland and let the most vulnerable areas disappear into the water. They may have found allies in the Federal Emergency Management Agency. After spending more than $278 billion on disaster relief over the past decade, the agency has begun to consider a change in tactics. In March, Bob Fenton, FEMA’s acting administrator, told a meeting of state emergency directors that governments need to find ways to reduce risk. “We need to move out of threatened areas,” he said. New Jersey shows just how hard that will be. Read More here
28 April 2017, Climate News Network, Sea floor erosion causes coral reefs to sink. Five US coral reefs are sinking beneath the waves due to the erosion of the sea floor, robbing coastal communities of their natural storm barrier. The world’s coral reefs are not just in hot water and under threat from acid attack; they may even be getting out of their depth. New research around five US coral reefs shows that even as sea levels rise, the sea floor around the reefs is being eroded. And coral growth simply may not be fast enough to keep up, which means that coastal communities in Florida, the Caribbean and Hawaii could become increasingly at risk from storms, waves and erosion. The news comes close after revelations that great tracts of Australia’s Great Barrier Reef, like other coral colonies, have been devastated by bleaching, as ocean temperatures rise above the levels that corals – animals that live in symbiosis with algae – can tolerate, and researchers have warned that this could soon be happening to reefs almost everywhere, every year. Coral under threat There is already widespread alarm among marine scientists as the seas become measurably more acidic due to an increase in levels of carbon dioxide in the atmosphere, and this too poses a threat to corals everywhere. But while researchers in the tropics had monitored the living reefs of the surface waters, hardly anybody had paid attention to the sea floor around the reefs. Now, scientists of the US Geological Survey report in Biogeosciences that – possibly as a consequence of the degradation of the reefs of the Florida Keys, the US Virgin Islands and the Hawaiian island of Maui – the sea floor is being scoured of sand and sediments, just as sea levels continue to creep to a predicted rise of up to a metre by 2100. Read More here