Most atolls will be uninhabitable by the mid-21st century because of sea-level rise exacerbating wave-driven flooding

Most atolls will be uninhabitable by the mid-21st century because of sea-level rise exacerbating wave-driven flooding

SOURCE: Science Advances DATE: April 25, 2018 SNIP: Sea levels are rising, with the highest rates in the tropics, where thousands of low-lying coral atoll islands are located. Most studies on the resilience of these islands to sea-level rise have projected that they will experience minimal inundation impacts until at least the end of the 21st century. However, these have not taken into account the additional hazard of wave-driven overwash or its impact on freshwater availability. We project the impact of sea-level rise and wave-driven flooding on atoll infrastructure and freshwater availability under a variety of climate change scenarios. We show that, on the basis of current greenhouse gas emission rates, the nonlinear interactions between sea-level rise and wave dynamics over reefs will lead to the annual wave-driven overwash of most atoll islands by the mid-21st century. This annual flooding will result in the islands becoming uninhabitable because of frequent damage to infrastructure and the inability of their freshwater aquifers to recover between overwash events. This study provides critical information for understanding the timing and magnitude of climate change impacts on atoll islands that will result in significant, unavoidable geopolitical issues if it becomes necessary to abandon and relocate low-lying island...
Sea levels could be rising faster than predicted due to new source of Antarctic ice melting

Sea levels could be rising faster than predicted due to new source of Antarctic ice melting

SOURCE: The Independent and Science Daily DATE: April 18, 2018 SNIP: Sea level rise could be happening at a faster rate than previously thought, as scientists have identified a new source of melting ice in Antarctica. Melting glaciers can create a positive feedback loop in which the more they melt, the more they drive further melting, according to the Australian team. They predict that the processes they identified could be playing a role in accelerating both sea level rise and climate change. As glaciers melt, they produce fresh water. When this meltwater enters the ocean surrounding the glacier it makes the surface layer less salty and therefore more buoyant. This leads to a layer of water floating on the surface, and prevents the natural mixing of the ocean. The lack of mixing becomes a problem during winter, as it prevents warm water at greater depths from mixing with cooler water above. With a pool of warm water underneath them, the melting of the bottom side of the glaciers...
Federal report: High-tide flooding could happen ‘every other day’ by late this century

Federal report: High-tide flooding could happen ‘every other day’ by late this century

SOURCE: Washington Post and NOAA DATE: March 28, 2018 SNIP: By 2100, a new NOAA report says, “high tide flooding will occur ‘every other day’ (182 days/year) or more often” even under an “intermediate low scenario” in coastal areas along the East Coast and Gulf of Mexico. This scenario works under the assumption that greenhouse gas emissions — which warm the climate and speed up sea-level rise — are curbed. For a more aggressive “intermediate” scenario, in which greenhouse gas emissions carry on at today’s pace, high-tide flooding is forecast to occur 365 days per year. The prospect of high-tide flooding occurring every day or even every other day late this century is difficult to fathom. Michael Lowry, a visiting scientist at the University Corporation for Atmospheric Research, expressed shock on Twitter after seeing these projections. “It’s hard to overstate the significance of this,” he said. “That isn’t even the intermediate high, high, or extreme scenarios that bring us 365 [days per year] high tide flooding in my lifetime. It’s crazy.” Astrid Caldas is a senior climate scientist at the Union of Concerned Scientists who tracks the effects of sea-level rise at the coast and is extremely worried about the projected flooding increases. “By mid-century, the frequency of this type of ‘minor’ flooding would become so disruptive that business as usual would be practically impossible without significant adaptation measures,” Caldas said. “Without planning for flooding with measures such as protecting, elevating, accommodating the water, or even moving stuff out of the way, the impacts on the cities, their economy, and their residents would be...
Sea level fears as more of giant Antarctic glacier floating than thought

Sea level fears as more of giant Antarctic glacier floating than thought

SOURCE: Agence France Presse DATE: March 20, 2018 SNIP: More of a giant France-sized glacier in Antarctica is floating on the ocean than previously thought, scientists said Tuesday, raising fears it could melt faster as the climate warms and have a dramatic impact on rising sea-levels. The Totten Glacier is one of the fastest-flowing and largest glaciers in Antarctica with scientists keen to keep a close eye on how it melts given the enormous amount of water it could potentially unleash. Using artificially created seismic waves that help scientists see through the ice, researchers have discovered that more of the Totten Glacier floats on the ocean than initially thought. The findings are important because recent studies have shown the Totten Glacier’s underbelly is already being eroded by warm, salty sea water flowing hundreds of kilometres inland after passing through underwater “gateways”. As it does, the portion of the glacier resting on water rather than rock increases, accelerating the pace of...
Sea Level Rise Will Rapidly Worsen Coastal Flooding in Coming Decades, NOAA Warns

Sea Level Rise Will Rapidly Worsen Coastal Flooding in Coming Decades, NOAA Warns

SOURCE: Inside Climate News DATE: March 7, 2018 SNIP: Coastal communities should expect much more frequent flooding in coming decades as sea levels rise, according to a new federal report. Many places that are dry now could flood every day by the end of the century. The report, published by the National Oceanic and Atmospheric Administration, projects the impact of sea level rise on coastal flooding along the nation’s shorelines and says it’s already having an effect, particularly on the East Coast. In the Southeast, the average number of days with high-tide floods has more than doubled since 2000, to three per year, while the number in the Northeast has increased by about 75 percent, to six per year. “We’re seeing an accelerated increase up and down most of the Atlantic Seaboard,” said William V. Sweet, an oceanographer at NOAA and the lead author of the report. “That’s not a good place to be, because impacts are going to become chronic rather quickly.” While Miami currently experiences only a few days of high-tide flooding per year, for example, it should expect 10 days each year by the early 2030s under an intermediate scenario for sea level rise. Just a decade later, that number could triple. And flooding would likely occur every other day by...