The Arctic is in even worse shape than you realize

The Arctic is in even worse shape than you realize

SOURCE: Washington Post DATE: December 11, 2018 SNIP: Over the last three decades of global warming, the oldest and thickest ice in the Arctic has declined by a stunning 95 percent, according the National Oceanic and Atmospheric Administration’s annual Arctic Report Card. The finding suggests that the sea at the top of the world has already morphed into a new and very different state, with major implications not only for creatures such as walruses and polar bears, but in the long term, perhaps, for the pace of global warming itself. The oldest ice can be thought of as a kind of glue that holds the Arctic together and, through its relative permanence, helps keep the Arctic cold even in long summers. If the Arctic begins to experience entirely ice-free summers, scientists say, the planet will warm even more, as the dark ocean water absorbs large amounts of solar heating that used to be deflected by the cover of ice. The new findings about the decreasing age of ice in the Arctic point to a less noticed aspect of the dramatic changes occurring there. When it comes to the icy cap atop the Arctic ocean, we tend to talk most often about its surface area — how much total ocean is covered by ice, rather than by open water. That’s easily visible — it can be glimpsed directly by satellite — and the area is, indeed, in clear decline. But the loss of old and thick ice, and the simultaneous decline in the total ice volume, is even larger — and arguably a much bigger deal. Young and thin ice...
Greenland is melting much faster than we thought

Greenland is melting much faster than we thought

SOURCE: Popular Science DATE: December 6, 2018 SNIP: Greenland is losing its cool. That’s not much of a surprise—its mile-thick sheet of ice was not made for this epoch of climate change. But that cool is getting shredded faster than we think. According to new findings published Wednesday in Nature, climate change has accelerated the melting of Greenland’s ice sheet to unparalleled levels, unseen in at least 350 years and likely in the past 7,800. The rate of melt and the resulting runoff falling into the ocean (and adding to a rising sea level) is speeding up over time, thanks to a motley of factors acting as a feedback loop. “By using ice cores, we can literally ‘drill back in time,’ and we are able to extend the observational period back in time ten-fold,” says Sarah Das, a glaciologist at Woods Hole Oceanographic Institution and a coauthor of the new study. In all, the team’s analysis suggests melt intensity in Greenland increased by a whopping 250 to 575 percent over just the last 20 years, relative to pre-industrial levels. In those same two decades, total ice sheet runoff has increased by 50 percent since the industrial age began, spiking up by 33 percent since the 20th century alone. Multiple factors are coalescing to create multiple feedback loops, all exacerbating the ice and snow melt. One of these is the melt-albedo feedback, in which melting creates a more granular consistency of snow that absorbs more sunlight and melts faster. Melting also exposes darker ice to sunlight, which warms up and melts faster than lighter shades of ice. And when melting...
Mysterious Microbes Turning Polar Ice Pink, Speeding Up Melt

Mysterious Microbes Turning Polar Ice Pink, Speeding Up Melt

SOURCE: National Geographic DATE: September 14, 2018 SNIP: A surprisingly happy and healthy ecosystem of algae is not only turning parts of the Greenland ice sheet pinkish-red, it’s contributing more than a little to the melting of one of the biggest frozen bodies of water in the world. The discolored snow isn’t just an Arctic phenomenon. “It’s actually a global occurrence,” says Alexandre Anesio, a biogeochemist from the University of Bristol. “In order for them to form visible blooms and increase the melting of the snow and ice, they just need the right conditions, which at a minimum involve basic nutrients and melting,” says Anesio. “As the climate gets warmer, the availability of liquid water from snow and ice becomes higher, favoring the growth of snow and ice algae.” “I think that this is increasingly becoming a problem in Arctic, Alpine, and Himalayan glaciers,” Anesio says. Blooms of red snow and brown ice are turning up in Antarctica, too. And experts are not accounting for the effect in their projections of global sea level rise, despite increasing evidence of what darkening snow is doing to the world’s glaciers. The darker surface [from the algae growth] lowers the “albedo,” or the ability of the ice to reflect the sunlight back into space, and that results in more light absorbed and more melting. As algae spreads over larger areas of the ice sheet, the effect will be compounded, leading to even more melting. A recent study found that algal blooms can contribute as much as 13 percent more ice melt over a season. So far, the blooms have not been taken...
How fast can Antarctica rise when the ice melts?

How fast can Antarctica rise when the ice melts?

SOURCE: Science Nordic DATE: September 8, 2018 SNIP: At the peak of the last ice age, ice covered a much larger area of the Amundsen Sea Embayment than it does today, but it shrank to reach its modern configuration around 10,000 years ago, as shown in the figure below. Since then, the glaciers in this region have been pretty much stable until about 200 years ago, when they started to melt and retreat. This happened slowly at first, but there has been a clear increase of ice loss since 2005. Our study shows that the Earth surface, progressively relieved from the big burden of ice, is finally rising and it is doing so at an accelerating pace – up to 41 millimetres a year in 2014, which is between four and five times faster than expected. Why does the land rise when the ice melts? To explain this, we need to understand the process by which the earth rises, known as glacial isostatic adjustment to give it its proper name. A useful analogy is to imagine the structure of the Earth beneath Antarctica as a double-layer mattress with a springy, elastic layer at the top and a thick, memory foam underneath. As the ice thins, the land immediately underneath the ice sheet quickly springs back in response to the loss of weight. This is like the springy layer at the top of your mattress, which springs back as you get out of bed. This immediate response is called elastic rebound. Secondly, there is a delayed uplift as the mantle beneath the bedrock responds. This is analogous to the deeper...
Antarctica’s Ice Loss Is Speeding Up, with Sharp Acceleration in Past 5 Years

Antarctica’s Ice Loss Is Speeding Up, with Sharp Acceleration in Past 5 Years

SOURCE: Inside Climate News and Nature DATE: June 13, 2018 SNIP: The most complete assessment to date of Antarctica’s ice sheets confirms that the meltdown accelerated sharply in the past five years, and there is no sign of a slowdown. That means sea level is expected to rise at a rate that will catch some coastal communities unprepared despite persistent warnings, according to the international team of scientists publishing a series of related studies this week in the journal Nature. The scientists found that the rate of ice loss over the past five years had tripled compared to the previous two decades, suggesting an additional 6 inches of sea level rise from Antarctica alone by 2100, on top of the 2 feet already projected from all sources, including Greenland. Between 1992, when detailed satellite measurements started, and 2012, Antarctica lost about 76 billion tons of ice per year. But since 2012, that rate has tripled to about 219 billion tons of ice loss per year, the scientists found. Another study, published June 13 in the journal Science Advances, raises even more concerns about the vulnerability of Antarctic ice to global warming. Data from radar and laser readings of the ice enabled scientists with the University of Texas at Austin and the University of Waterloo to map a vast network of channels in the base of many ice sheets formed by intrusions of warm water. Some are several kilometers wide, said University of Texas at Austin researcher Jamin Greenbaum. They found the channels everywhere they looked, including beneath the ice shelf of the Totten Glacier, in East Antarctica, as well...