字幕表 動画を再生する 英語字幕をプリント Geoscientists spend their lives studying features in nature that move very, very slowly. Glacial melt, plate tectonics, things like these take their sweet time to develop. So, when an entire river vanishes in just four days, it's safe to assume geoscientists are going to freak out. A paper recently published in Nature called this very sudden disappearing act “river piracy.” Sadly, there were no actual pirates involved in the making of this study … but river piracy, or it's less exciting name, “stream capture”, is a geomorphic phenomenon where one river captures and redirects the flow of another. In 2015, a team of scientists observed that the Slims River in the Yukon was [quote] "swift, cold and deep," flowing from one of Canada's largest glaciers north to the Bering Strait. Luckily for us, NASA was watching. Check this out. In 2015, a team of scientists observed that the Slims River in the Yukon was [quote] "swift, cold and deep," flowing from one of Canada's largest glaciers north to the Bering Strait. Then in 2016 they came back and the river was completely different. Its waterflow was at a near screeching halt. THEN in 2016 NASA took this picture. The scientists on the ground came back and the river was completely different. Its waterflow was at a near screeching halt. It looked more like “a long, skinny lake,” and they could see the water level dropping by the day. What had happened was, a tall canyon had formed at the end of the nearby glacier, rerouting melt water from the Slims to the Kaskawulsh River, joining the Alsek River south. Basically, the Slims river was stolen by another river, and it just completely changed course! This shift is affecting fish populations, wildlife, lake chemistry in the area, even sheep are changing their grazing patterns. Which all sounds kind of meh. BUT. Think about how this could affect everything else! Land degradation and lack of freshwater will impact billions of people globally. Plus, there may be more consequences that we haven't even thought of yet! This is the first time in modern history that scientists have actually seen a river do this. A whole river was going north, now it's going south! That's huge. And why? Of course you already know. Man-made climate change. But not global warming as a whole, instead, one of its many facets: glacial retreat. Glaciers are these massive bodies of snow and ice that change in response to temperature and precipitation. When a glacier starts to retreat due to high temperature or less snowfall, glacial melt will outpace new accumulation of snow and ice. This affects the availability of fresh water for animals, plants … even humans! This connects to the river piracy in the Yukon, because the massive Canadian glacier that fed the Slims River is in retreat, thanks to a cold period centuries ago called the Little Ice Age and warming due to greenhouse gases. Now while this study was just one glacier and we shouldn't generalize too much, glacial retreat is a worldwide phenomenon. Glaciers in the Himalayas, Andes, Alps, and Rockies are all backpedaling at greater speeds in response to our globe's changing climate. Of course, glacial melt is happening in some of the farthest corners of our planet and only a small number of communities are directly affected, for now. So, while global warming is a multi-century process; things can happen quickly… Consequences of global warming and climate change are being seen now. And huge parts of the environment can change course in just a matter of days… And no one knows what this will mean for the future… So if all these glaciers keep retreating, what happens if all the world's ice melts? Check out this video here to learn more about that. What's your favourite piece of evidence that climate change is happening? Let us know in the comments, like this video, and subscribe!
B2 中上級 米 When a River Goes Missing, It's Kind of a Big Deal... 29 2 joey joey に公開 2021 年 04 月 14 日 シェア シェア 保存 報告 動画の中の単語