The fast-melting Arctic is already messing with the ocean’s circulation, scientists say

The fast-melting Arctic is already messing with the ocean’s circulation, scientists say

SOURCE: Washington Post DATE: March 14, 2018 SNIP: Scientists studying a remote and icy stretch of the North Atlantic have found new evidence that fresh water, likely melted from Greenland or Arctic sea ice, may already be altering a key process that helps drives the global circulation of the oceans. In chilly waters on either side of Greenland, the ocean circulation “overturns,” as surface waters traveling northward become colder and more dense and eventually sink, traveling back southward toward Antarctica at extreme depths. This key sinking process is called convection. But too much fresh water at the surface could interfere with it, because with less salt, the water loses density and does not sink as easily. In the new research, Marilena Oltmanns and two colleagues at the GEOMAR Helmholtz Center for Ocean Research in Kiel, Germany, found that following particularly warm summers in the remote Irminger Sea, convection tended to be more impaired in winter. In some cases, a layer of meltwater stayed atop the ocean into the next year, rather than vanishing into its depths as part of the overturning circulation, which has sometimes been likened to an ocean “conveyor belt.” “Until now, models have predicted something for the future … but it was something that seemed very distant,” said Oltmanns, the lead scientist behind the research, which was published this week in Nature Climate Change. “But now we saw with these observations that there is actually freshwater and that it is already affecting convection, and it delays convection quite a lot in some years,” she...
Melting ice may be making mountains collapse in Greenland

Melting ice may be making mountains collapse in Greenland

SOURCE: New Scientist DATE: July 11, 2017 SNIP: Earthquakes in Greenland are rare. At least, they’re supposed to be. But a few weeks ago, a 4.1 “quake” struck Nuugaatsiaq, a tiny island off Greenland’s west coast, triggering a massive tsunami that smashed homes, leaving at least four people dead. But what residents – and seismic equipment – initially labelled a quake may be nothing of the sort. “Everyone was fooled by the collapse of a mountain,” says Martin Luethi, a Swiss glaciologist who has been studying Greenland’s glaciers since 1995. “The tsunami wasn’t triggered by an earthquake.” Luethi believes the culprit was a landslide at nearby Karrat fjord. And as the falling mountain hit the ocean, it created enough seismic noise to dupe sensors and generate the waves that inundated Nuugaatsiaq. That’s why there’s such a powder keg brewing, Luethi says. The landslide in Nuugaatsiaq was reportedly 1000 metres in length and 300 metres wide. And while the ensuing tsunami was disastrous, it’s shifting focus from the real problem: this wasn’t a one-off. This region is full of craggy fjords undergoing temporal shift. Meaning more so-called quakes – and accompanying tsunamis – seem...
Polar bears shift from seals to bird eggs as Arctic ice melts

Polar bears shift from seals to bird eggs as Arctic ice melts

SOURCE: New Scientist DATE: May 12, 2017 SNIP: Polar bears are ditching seafood in favour of scrambled eggs, as the heat rises in the Arctic melting the sea ice. A changing coastline has made it harder for the predators to catch the seals they favour and is pushing them towards poaching goose eggs. “It takes on average 30 seconds to locate a nest and 60 seconds to eat the eggs,” he says. Previous research found that affected bird populations can slump by up to 90 per cent. As the bears move on to eating bird eggs for sustenance, what will happen to the geese population in the future? “If numbers decline – which is to be expected – this will have an impact on the whole terrestrial ecosystem,” says Prop. “For example, Arctic foxes depend on young geese as food; reindeer food intake is facilitated by geese grazing the...