Category Archives: Impacts Observed & Projected

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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

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20 April 2017, Bloomberg Climate Changed, The Nightmare Scenario for Florida’s Coastal Homeowners. Demand and financing could collapse before the sea consumes a single house. On a predictably gorgeous South Florida afternoon, Coral Gables Mayor Jim Cason sat in his office overlooking the white-linen restaurants of this affluent seaside community and wondered when climate change would bring it all to an end. He figured it would involve a boat. When Cason first started worrying about sea-level rise, he asked his staff to count not just how much coastline the city had (47 miles) or value of the property along that coast ($3.5 billion). He also told them to find out how many boats dock inland from the bridges that span the city’s canals (302). What matters, he guessed, will be the first time a mast fails to clear the bottom of one of those bridges because the water level had risen too far. “These boats are going to be the canary in the mine,” said Cason, who became mayor in 2011 after retiring from the U.S. foreign service. “When the boats can’t go out, the property values go down.” Jim Cason, mayor of Coral Gables, in his office. He worries that rising insurance costs, reluctant lenders or skittish foreign buyers could hurt home prices well before sea-level rise gets worse. If property values start to fall, Cason said, banks could stop writing 30-year mortgages for coastal homes, shrinking the pool of able buyers and sending prices lower still. Those properties make up a quarter of the city’s tax base; if that revenue fell, the city would struggle to provide the services that make it such a desirable place to live, causing more sales and another drop in revenue. And all of that could happen before the rising sea consumes a single home. As President Donald Trump proposes dismantling federal programs aimed at cutting greenhouse gas emissions, officials and residents in South Florida are grappling with the risk that climate change could drag down housing markets. Relative sea levels in South Florida are roughly four inches higher now than in 1992. The National Oceanic and Atmospheric Administration predicts sea levels will rise as much as three feet in Miami by 2060. By the end of the century, according to projections by Zillow, some 934,000 existing Florida properties, worth more than $400 billion, are at risk of being submerged. Read More here

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12 April 2017, Nature, Antarctica’s sleeping ice giant could wake soon. The massive East Antarctic Ice Sheet looks stable from above — but it’s a dangerously different story below. These first direct observations confirmed a fear that researchers had long harboured: that warm waters from the surrounding ocean can sneak underneath the floating glacier tongue and eat the ice away from below1. “This could explain why Totten has been thinning in the past few decades,” says Rintoul. Findings such as these are revealing some scary truths about East Antarctica — the vast, remote landmass to the east of the Transantarctic Mountains (see ‘Ice king’). This region is about as big as the entire United States and the majority of it stands on a high plateau up to 4,093 metres above sea level, where temperatures can plunge to −95 °C. Because the East Antarctic Ice Sheet seems so cold and isolated, researchers thought that it had been stable in the past and was unlikely to change in the future — a stark contrast to the much smaller West Antarctic Ice Sheet, which has raised alarms because many of its glaciers are rapidly retreating. In the past few years, however, “almost everything we thought we knew about East Antarctica has turned out to be wrong”, says Tas van Ommen, a glaciologist at the Australian Antarctic Division in Kingston, near Hobart. By flying across the continent on planes with instruments that probe beneath the ice, his team found that a large fraction of East Antarctica is well below sea level, which makes it more vulnerable to the warming ocean than previously thought. The researchers also uncovered clues that the massive Totten glacier, which holds about as much ice as West Antarctica, has repeatedly shrunk and grown in the past2 — another sign that it could retreat in the future. Read More here

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10 April 2017, The Guardian, Great Barrier Reef at ‘terminal stage’: scientists despair at latest coral bleaching data. ‘Last year was bad enough, this is a disaster,’ says one expert as Australia Research Council finds fresh damage across 8,000km. Back-to-back severe bleaching events have affected two-thirds of Australia’s Great Barrier Reef, new aerial surveys have found. The findings have caused alarm among scientists, who say the proximity of the 2016 and 2017 bleaching events is unprecedented for the reef, and will give damaged coral little chance to recover. Australia’s politicians have betrayed the Great Barrier Reef and only the people can save it | David Ritter Scientists with the Australian Research Council’s Centre of Excellence for Coral Reef Studies last week completed aerial surveys of the world’s largest living structure, scoring bleaching at 800 individual coral reefs across 8,000km. The results show the two consecutive mass bleaching events have affected a 1,500km stretch, leaving only the reef’s southern third unscathed.Where last year’s bleaching was concentrated in the reef’s northern third, the 2017 event spread further south, and was most intense in the middle section of the Great Barrier Reef. This year’s mass bleaching, second in severity only to 2016, has occurred even in the absence of an El Niño event. Mass bleaching – a phenomenon caused by global warming-induced rises to sea surface temperatures – has occurred on the reef four times in recorded history. Prof Terry Hughes, who led the surveys, said the length of time coral needed to recover – about 10 years for fast-growing types – raised serious concerns about the increasing frequency of mass bleaching events. “The significance of bleaching this year is that it’s back to back, so there’s been zero time for recovery,” Hughes told the Guardian. “It’s too early yet to tell what the full death toll will be from this year’s bleaching, but clearly it will extend 500km south of last year’s bleaching.” Read more here