Retreating Antarctic Glacier Could Raise Sea Levels 5 Feet
Antarctica's Denman Canyon is the deepest gorge on the Earth's surface, and, if the ice inside it melted, it could raise sea levels by almost five feet.
Now, research published in Geophysical Research Letters Monday looked at how close that might be to happening and found that the glacier had retreated five kilometers (approximately three miles) in the last 22 years, according to a University of California Irvine (UCI) press release.
"If warm water continues to induce high rates of ice melt near the glacier grounding zone, the potential exists for Denman Glacier to undergo a rapid and irreversible retreat, with major consequences for sea level rise," the researchers concluded.
The study, carried out by scientists at UCI and the National Aeronautics and Space Administration's (NASA) Jet Propulsion Laboratory, is the most detailed of the glacier to date. It found that it has lost 268 billion tons of ice between 1979 and 2017. It also noticed that the glacier's grounding line ― the point where the ice begins to flow into the ocean ― had retreated asymmetrically, falling back mostly on the Western side.
BBC News explained why:
The reason, the scientists can now determine, is a buried ridge under the eastern flank which is pinning and protecting that side of the glacier. In contrast, the western flank features a narrow but sizeable trough that would allow warm ocean water to erode the grounding line and push it backwards.
This potentially is an Achilles heel. The further inland the glacier reaches, the deeper its bed - which is a geometry that has been demonstrated to favour more and more melting. If a lot of warm ocean water can find its way to the front of Denman, the opportunity is there to melt out its ice in a significant way.
NASA's Dr. Virginia Brancato told BBC News it was impossible to say how fast that ice would melt and that the narrowness of the channel that housed the glacier might also slow down its retreat.
"At present, it is critical to collect more data, and closely and more frequently monitor the future evolution of the glacier," she told BBC News.
The findings also reflect growing concern among researchers about East Antarctica, where the glacier is located. The region is considered more stable than fast-melting West Antarctica, but that is changing.
"East Antarctica has long been thought to be less threatened, but as glaciers such as Denman have come under closer scrutiny by the cryosphere science community, we are now beginning to see evidence of potential marine ice sheet instability in this region," study co-author and UCI scientist Eric Rignot said in the university release. "The ice in West Antarctica has been melting faster in recent years, but the sheer size of Denman Glacier means that its potential impact on long-term sea level rise is just as significant."
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At first glance, you wouldn't think avocados and almonds could harm bees; but a closer look at how these popular crops are produced reveals their potentially detrimental effect on pollinators.
Migratory beekeeping involves trucking millions of bees across the U.S. to pollinate different crops, including avocados and almonds. Timothy Paule II / Pexels / CC0<p>According to <a href="https://www.fromthegrapevine.com/israeli-kitchen/beekeeping-how-to-keep-bees" target="_blank">From the Grapevine</a>, American avocados also fully depend on bees' pollination to produce fruit, so farmers have turned to migratory beekeeping as well to fill the void left by wild populations.</p><p>U.S. farmers have become reliant upon the practice, but migratory beekeeping has been called exploitative and harmful to bees. <a href="https://www.cnn.com/2019/05/10/health/avocado-almond-vegan-partner/index.html" target="_blank">CNN</a> reported that commercial beekeeping may injure or kill bees and that transporting them to pollinate crops appears to negatively affect their health and lifespan. Because the honeybees are forced to gather pollen and nectar from a single, monoculture crop — the one they've been brought in to pollinate — they are deprived of their normal diet, which is more diverse and nourishing as it's comprised of a variety of pollens and nectars, Scientific American reported.</p><p>Scientific American added how getting shuttled from crop to crop and field to field across the country boomerangs the bees between feast and famine, especially once the blooms they were brought in to fertilize end.</p><p>Plus, the artificial mass influx of bees guarantees spreading viruses, mites and fungi between the insects as they collide in midair and crawl over each other in their hives, Scientific American reported. According to CNN, some researchers argue that this explains why so many bees die each winter, and even why entire hives suddenly die off in a phenomenon called colony collapse disorder.</p>
Avocado and almond crops depend on bees for proper pollination. FRANK MERIÑO / Pexels / CC0<p>Salazar and other Columbian beekeepers described "scooping up piles of dead bees" year after year since the avocado and citrus booms began, according to Phys.org. Many have opted to salvage what partial colonies survive and move away from agricultural areas.</p><p>The future of pollinators and the crops they help create is uncertain. According to the United Nations, nearly half of insect pollinators, particularly bees and butterflies, risk global extinction, Phys.org reported. Their decline already has cascading consequences for the economy and beyond. Roughly 1.4 billion jobs and three-quarters of all crops around the world depend on bees and other pollinators for free fertilization services worth billions of dollars, Phys.org noted. Losing wild and native bees could <a href="https://www.ecowatch.com/wild-bees-crop-shortage-2646849232.html" target="_self">trigger food security issues</a>.</p><p>Salazar, the beekeeper, warned Phys.org, "The bee is a bioindicator. If bees are dying, what other insects beneficial to the environment... are dying?"</p>
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