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  • A funny thing happens if you travel north in January.

  • Go far enough and it gets dark in the middle of the day.

  • This is what the brief winter daylight looks like in northern Norway.

  • That's where I meet up with a team of researchers bound for the Arctic Ocean.

  • I'm Eli Kintisch and I'm spending two weeks with scientists

  • exploring the Arctic during the polar night.

  • The time of year that brings 24-hour darkness.

  • We're here in the dark to study the Arctic ecosystem before

  • the ice that defines it disappears.

  • Seasons are supercharged in the Arctic.

  • As the Earth orbits the Sun,

  • the amount of light reaching the northern hemisphere changes.

  • You may have noticed your days shrinking in the winter,

  • but it's way more drastic near the North Pole.

  • Where for four months the Sun never rises above the horizon,

  • and then in the summer, the Sun never sets.

  • The sea ice floating on the Arctic Ocean

  • follows a similar pattern.

  • Growing in the fall and winter and melting in the spring

  • when the massive spring blooms of algae feed the ecosystem.

  • But alongside those drastic seasons,

  • scientists have also detected a long-term trend that's underway.

  • Back here on earth, new word that the Arctic sea ice

  • has melted to near record levels.

  • Global warming will leave the Arctic ice free

  • during the summer within two decades.

  • Look at where the sea ice was in the 1980s

  • compared to the first decade of the 2000s.

  • And this line shows the data from 2018 so far.

  • Twenty years ago, the part of the sea we explored on the Helmer Hanssen

  • would have been coated with ice three to six feet thick.

  • We visit 22 stations on our journey

  • collecting measurements and samples

  • to gauge the health of the ecosystem

  • before the light returns in the spring.

  • Scientists have mostly ignored the Arctic winter

  • assuming that life here is dormant during the dark months.

  • But when they looked closer, they found an ecosystem teeming with life.

  • The mission of this journey is to track the physical and biological

  • aspects of the ocean as the ice vanishes above it.

  • Water samples from the deep helped scientists

  • identify currents that may be changing.

  • Robotic gliders roam the sea for months

  • measuring the properties of water

  • and probing for signs of life.

  • You've probably heard that big arctic species like

  • polar bears are endangered by the melting ice,

  • but tiny creatures also rely on it.

  • Some types of algae cling to its surface

  • and when they die, they fall to the muddy sea floor

  • becoming food for mollusks, worms, and crustaceans

  • and those creatures are food for fish, seals, and ...

  • walruses.

  • Stir crazy scientists really like walruses.

  • Other scientists zap the water with light to

  • detect algae cells and measure their response.

  • Animals called zooplankton just a few millimeters long

  • come up in the nets.

  • And the scientists test how they behave

  • under different light and water conditions.

  • They also document which species are present

  • and how many. As do the team's studying fish.

  • Without this data we won't be able to measure

  • how less ice and more light will change the ecosystem.

  • Shrinking sea ice means more light reaches

  • the Arctic Ocean in the spring and fall.

  • And that light is fueling massive new

  • blooms of algae called phytoplankton.

  • That's already helping several species of whales

  • thrive in the Arctic.

  • But will the extra light benefit the entire ecosystem in the future?

  • It depends.

  • These nutrients like nitrogen and phosphate

  • are found naturally in the ocean.

  • They nourish the algae like fertilizer for a garden.

  • But we don't know whether their levels will rise

  • along with all the new sunlight.

  • As the light floods in a separate problem is disruptions in timing.

  • The blooms are coming earlier in the spring on average.

  • But if they appear too early baby zooplankton that

  • hatch later could go hungry. And fish populations in turn

  • would diminish as well.

  • The Arctic has undergone massive changes before.

  • But carbon pollution is causing Arctic

  • summer temperatures to rise faster than they have in 1,500 years.

  • It is too soon to know how severe these disruptions

  • will be on the ecosystem.

  • So scientists will return to the same stations in the spring and early summer

  • to monitor a rapidly changing landscape.

  • Thanks for watching Thaw.

  • The next episode in this three-part series

  • we'll look at how the Arctic could be affecting

  • weather across the world.

A funny thing happens if you travel north in January.

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B1 中級 美國腔

海冰融化对北极的生命意味着什么(What melting sea ice means for life in the Arctic)

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    joey joey 發佈於 2021 年 05 月 16 日
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