Under the Ice in Antarctica and Greenland: More Future Warming and a Past Cooling Down

Candice Gaukel Andrews December 18, 2018 0
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The volcanoes under the frozen expanses in Antarctica may have far more consequences for the planet than those in Hawaii, Yellowstone National Park or Iceland.

If you were asked to name active volcano sites around the world, you’d probably include places such as Hawaii, Yellowstone National Park and Iceland, the country often labeled “the land of fire and ice.” But what’s under the white, frozen expanses in Antarctica may be far more dramatic.

Just last year, Scotland-based researchers discovered 91 previously unknown volcanoes beneath West Antarctica’s giant ice sheet, approximately 2.5 miles down. This officially makes the region the largest known concentration of volcanoes on the planet, overshadowing the number found in East Africa around Mount Kilimanjaro and those in North America’s Basin and Range Province, which extends across much of the western United States. And earlier this year, a crater—likely caused by a meteor—was found under the ice in Greenland.

Both of these discoveries shed light on the workings of our globe’s climate—and one of them may portend direr (if that’s possible) climate-related events in the future.

Antarctica: future hot

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Currently, Antarctica loses more than 130 billion tons of ice a year. That number is expected to rise as rapid climate change causes global temperatures to soar.

According to researchers at Edinburgh University, who published their findings in the Geological Society’s Special Publications series in May 2017, the total number of volcanoes in the 1,800-mile-long West Antarctic Rift System now stands at 138. What’s still unknown is how many of these volcanoes—which range in height from around 300 feet to 12,600 feet—are active.

While early explorers had already identified a few dozen Antarctic volcanoes, such as Mount Erebus, no one suspected that a lot more lurked beneath the surface. But by looking through decades’ worth of data from ice-penetrating radar carried by land vehicles and planes, seismic studies and other modern tools, the Edinburgh team gleaned the shapes of nearly 200 cones.

Some of these cones were ruled out from the recent study because satellite photos showed no corresponding deformation on the ice above the cones or because they exactly matched the locations of previously discovered volcanoes. But 91 of them, the team concluded, were true volcanoes that have never seen the light of day. And, there are most likely many more that have yet to be found. If the ice were to suddenly vanish, these volcanoes would poke out of the sea, some towering nearly two-and-a-half miles high.

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Greenland ice has melted more in recent decades than at any point in at least the last four centuries, according to a recent paper published in the science journal “Nature.”

What’s worrying is that volcanic activity could have a major compounding effect on Antarctica’s already diminishing ice. In fact, a March 2016 study published in the journal Nature concluded that at current rates of global warming, Antarctic ice melt could contribute up to 3.2 feet in global sea-level rise by 2100. And that was before we knew just how many potentially very hot geological structures were underneath all that ice.

Currently, the continent loses more 130 billion tons of ice a year, a number that is expected to increase as global temperatures rise. Although the volcanoes are buried under thick layers of ice now, any eruption of hot lava could lead to more widespread melting in the area. It’s a continuous loop that all leads to more melting: as the heavy layers of ice melt due to global warming, some of the pressure that might have been keeping the underlying volcanos quiet is freed up, and the resulting flow of molten lava would cause even more melting.

That would add to the rising sea levels that already pose a threat to coastal communities around the world. And there’s a precedent for that: when Iceland thawed out 10,000 years ago, the land beneath the disappearing ice rose up, and pressure-sensitive volcanoes spewed to life.

Antarctica might respond the same way.

Greenland: past cold

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Greenland’s Ice Sheet covers 660,000 square miles and is more than a mile thick. If it all melts, it would raise global sea levels by 25 feet.

What’s hidden beneath the ice in northwest Greenland may be a bit less sinister, but it’s still as intriguing regarding our climate.

Unlike on the moon or Mercury, where impact craters dominate the landscape, the pock marks caused by meteor strikes on Earth are much harder to find. Our atmosphere limits the size of incoming rocks from space, and erosion and rainfall often erase traces of their visits. But some of the depressions survive the eons, and researchers have just found one of the largest ever discovered trapped beneath the ice of Greenland’s Hiawatha Glacier.

Scientists from NASA’s IceBridge mission, the largest airborne survey of Earth’s polar ice ever flown and which uses radar to track changes in the ice in Greenland, were the first to detect signs of the crater. They noticed an anomaly underneath Hiawatha that appeared to be a 19-mile-wide, 1,000-foot-deep crater—which would be one of the 25 largest impact craters on Earth and the first to be found under ice.

For three years, researchers from the University of Copenhagen’s Center for GeoGenetics worked to confirm the NASA data. Satellite images showed a circular depression in the surface of the ice. A German research plane equipped with a new type of high-powered, ice radar mapped the crater in exquisite detail. On the ground, samples of sediment from channels washing out of the crater were collected, which included bits of shocked quartz that can only be formed during a high-energy impact. The results, reported in the journal Science Advances in November 2018, showed that there is, indeed, a crater locked beneath the ice.

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Runoff from the vast Greenland Ice Sheet is 50 percent higher than preindustrial levels and increasing exponentially as a result of man-made global warming.

So far, it has not been possible to directly date the crater, but its condition strongly suggests that it formed after ice began to cover Greenland. That means that it is younger than 3 million years old and possibly as new as 12,000 years old—which would place the crater among the youngest on the planet, toward the end of the last Ice Age. It’s believed that to create the crater, the iron meteor (determined by measurements of platinum and other elements in glacial outwash sediments) that struck Greenland would have had to be half a mile to a mile wide and have the force of a 700-megaton warhead. Such an impact would have been felt hundreds of miles away, would have warmed up that area of Greenland and may have rained rocky debris down not only on Europe but on North America, as well.

But that’s not the only “impact” this crater may signify. About 12,800 years ago, toward the end of the last Ice Age, the world steadily began to warm up. Then, abruptly, the paleoclimate record shows that temperatures plummeted back to Ice Age norms for about 1,000 years, a cooling period called the Younger Dryas that has no definite explanation. According to one theory, this crater may explain the mystery. The impact of a 10-billion-ton space rock, proponents say, would have unleashed 47 million times the energy of the nuclear bomb dropped on Hiroshima in 1945. It would have melted vast amounts of ice, sending fresh water rushing into the oceans, diluting the current that transports warm water through the Atlantic and causing a refreeze.

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The ice holds lots of secrets, more of which will be revealed as the planet warms.

Some have even suggested such an event could have led to massive forest fires in Europe and North America, with soot and other particles from the fires blocking out the sun, causing the cold snap. That, they say, would lead to the end of megafauna such as the mastodon and the human communities that hunted them, which also disappear from the record around this time.

Secrets: present surfacing

It seems there are lots of secrets in the ice. And as our planet rapidly rushes toward evermore warming, for better or for worse, it looks like we’ll be continually discovering them.

Here’s to finding your true places and natural habitats,

Candy

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