30 March 2016, Science Daily, No snow, no hares: Climate change pushes emblematic species north. If there is an animal emblematic of the northern winter, it is the snowshoe hare. A forest dweller, the snowshoe hare is named for its big feet, which allow it to skitter over deep snow to escape lynx, coyotes and other predators. It changes color with the seasons, assuming a snow-white fur coat for winter camouflage. But a changing climate and reduced snow cover across the north is squeezing the animal out of its historic range, according to a new study by researchers at the University of Wisconsin-Madison. Writing in the current (March 30, 2016) Proceedings of the Royal Society B, the Wisconsin researchers report that the range of the hare in Wisconsin is creeping north by about five and a half miles per decade, closely tracking the diminishing snow cover the animal requires to be successful. “The snowshoe hare is perfectly modeled for life on snow,” explains Jonathan Pauli, a UW-Madison professor of forest and wildlife ecology and one of the co-authors of the new study. “They’re adapted to glide on top of the snow and to blend in with the historical colors of the landscape.” As climate warms, northern winters have become shorter and milder. And the annual blanket of snow that many organisms have evolved to depend on is in steady retreat, becoming thinner and less dependable in regions that once experienced snow well into the spring months. The Wisconsin study is important because it helps illustrate the effects of climate change on a sentinel species for northern ecosystems, showing how the composition of plants and animals on the landscape is gradually shifting in a warming world. The findings also signal that climate change is beginning to eclipse land use as the dominant driver of ecological change. Read More here
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30 March 2016, Climate Central, Antarctica at Risk of Runaway Melting, Scientists Discover. The world’s greatest reservoir of ice is verging on a breakdown that could push seas to heights not experienced since prehistoric times, drowning dense coastal neighborhoods during the decades ahead, new computer models have shown. A pair of researchers developed the models to help them understand high sea levels during previous eras of warmer temperatures. Then they ran simulations using those models and found that rising levels of greenhouse gases could trigger runaway Antarctic melting that alone could push sea levels up by more than three feet by century’s end. The same models showed that Antarctica’s ice sheet would remain largely intact if the most ambitious goals of last year’s Paris agreement on climate change are achieved. The new findings were published Wednesday in the journal Nature, helping to fill yawning gaps in earlier projections of sea level rise. The models were produced by a collaboration between two scientists that began in the 1990s. In those models, rising air temperatures in Antarctica caused meltwater to seep into cracks in floating shelves of ice, disintegrating them and exposing sheer cliffs that collapsed under their own weight into the Southern Ocean. Similar effects of warming are already being observed in Greenland and in some parts of Antarctica, as greenhouse gas pollution from fossil fuels, farming and deforestation warms the air. Last year was the hottest on record, easily surpassing a record set one year earlier. The ice sheets are also being melted from beneath by warming ocean temperatures. “Sea level has risen a lot — 10 to 20 meters — in warm periods in the past, and our ice sheet models couldn’t make the Antarctic ice sheet retreat enough to explain that,” said David Pollard, a Penn State climate scientist who produced Wednesday’s study with UMass professor Robert DeConto. “We were looking for new mechanisms that could make the ice more vulnerable to climate warming to explain past sea level rise,” Pollard said. Read More here
29 March 2016, The Guardian, Arctic sea ice extent breaks record low for winter. A record expanse of Arctic sea never froze over this winter and remained open water as a season of freakishly high temperatures produced deep – and likely irreversible – changes on the far north. Scientists at the National Snow and Ice Data Centre said on Monday that the sea ice cover attained an average maximum extent of 14.52m sq km (5.607m sq miles) on 24 March, the lowest winter maximum since records began in 1979. The low beats a record set only last year of 14.54m sq km (5.612m sq miles), reached on 25 February 2015. “I’ve never seen such a warm, crazy winter in the Arctic,” said NSIDC director Mark Serreze. “The heat was relentless.” It was the third straight month of record lows in the sea ice cover, after extreme temperatures in January and February stunned scientists. The winter months of utter darkness and extreme cold are typically the time of maximum growth in the ice cap, until it begins its seasonal decline in spring. With the ice cover down to 14.54m sq km, scientists now believe the Arctic is locked onto a course of continually shrinking sea ice – and that is before the 2016 melt season gets underway. Read More here
28 March, Science Daily, Climate change: Greenland melting tied to shrinking Arctic sea ice. Vanishing Arctic sea ice. Dogged weather systems over Greenland. Far-flung surface ice melting on the massive island. These dramatic trends and global sea-level rise are linked, according to a study coauthored by Jennifer Francis, a research professor in Rutgers University’s Department of Marine and Coastal Sciences. During Greenland summers, melting Arctic sea ice favors stronger and more frequent “blocking-high” pressure systems, which spin clockwise, stay largely in place and can block cold, dry Canadian air from reaching the island. The highs tend to enhance the flow of warm, moist air over Greenland, contributing to increased extreme heat events and surface ice melting, according to the study. That, in turn, fuels sea-level rise, said Francis, who called rising seas a “monstrous” issue for coastal communities around the world. The increased melting on the Greenland ice sheet in recent years may also be linked to cooler-than-normal ocean temperatures south of the island, slowing ocean circulation. The study, published online in the Journal of Climate last month, tapped computer models and measurements in the field. “I think this study does a good job of pinning down the fact that the [Arctic sea] ice is disappearing for a whole bunch of reasons — and that is causing the surface of Greenland’s melt area to increase,” Francis said. The Greenland ice sheet holds an enormous volume of frozen water, and the global sea level would rise about 20 to 23 feet if it all melted, the study notes. Surface melting of the ice sheet has increased dramatically since the relative stability and modest snow accumulation in the 1970s, the study also notes. Read More here