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  • Desertification, is the degradation of a productive, lush environment into dry, dry desert. Great

  • for MarioKart and alien planets in movies, but terrible for growing food.

  • Planet Earth is a constantly shifting landscape of 8 biomes, ranging from rainforest to grassland,

  • desert to taiga. Twenty-two thousand years ago, the Sahara was pretty much uninhabited,

  • except for the area around the Nile Valley. 10,500 years ago, monsoon rains rolled in

  • to wet it up. Climates change, it happens, and sometimes they change hella dramatically

  • like when whole deserts completely shift their borderswhich is happening RIGHT NOW.

  • Only a few thousands years ago, the Sahara was green and lush, and now we can't even

  • IMAGINE itinstead, research has found the Sahara's shifting sands are expanding,

  • causing die-offs of vegetation, failure of agriculture, and increased erosion without

  • plants to hold the soil in place. But this wasn't always the case. Scientists had hypotheses

  • that an ancient river ran through the Western Sahara, feeding the land and securing it with

  • vegetation. Clues were left off the coast of Mauritania, where researchers found sediment

  • resembling that of a huge riverbut there was no river around, only arid sands. They

  • called this ancient waterway the Tamanrasset and now, according to a recent study by the

  • Japanese Advanced Land Observing Satellite, it's real! And was confirmed recently using

  • microwave radar. If it were still there, the Tamanrassat river would be the 12th largest

  • on Earth, winding 300 miles inland (500km) to the Mauritanian coast.

  • As the researchers point out, climate change happens fast. In a study in Earth and Planetary

  • Science Letters researchers looked at 30,000 years of dust blown from Africa into the Atlantic.

  • Over the millennia the amount of blown dust rose and fell in lockstep with the amount

  • of moisture on the continent; less moisture, more dust, more moisture, less dust. Today,

  • because it's so dry, the majority of the sediment in the Atlantic is from Saharan dust! It can

  • (and does) reach North America! By looking at this dust, they know about 6,000 years

  • ago the African Humid Period ended suddenly, coinciding with an axial change in the Earth's

  • ORBIT. According to research from NASA and climate scientists, the Sahara exists, in

  • part, because the Earth's spin changed, decreasing Northern Hemisphere monsoons, and causing

  • the Sahara to grow. Vegetation died very quickly and the third largest desert in the world

  • took over North Africa, all in less than 300 years! In a separate study in the journal

  • Science, one of the jet streams which moves hot dry air across the planet's Equator, has

  • shifted northward, causing the tropics to expand 140 miles northward in the last 26

  • years; and with itthe deserts of Earth. Why? They're not sure, but they know global

  • warming is part of it, as is the ROTATION OF THE EARTH.

  • In the movies, when a wizard summons a massive storm, the storm dissipates at the moment

  • of his defeat. In reality, when we make huge changes to the Earth's climate, those changes

  • are not felt, or easily reversed across multiple human lifespans. According to NASA's Jet Propulsion

  • Laboratory, the melting of Greenland ice is changing the way the Earth spins, changing

  • the tilt of Earth's axis by 2.6 centimeters per year, with an increase in that tilt on

  • the horizon! Why is the ice melting? You need only look in a mirror. We live on a spinning

  • top, and we're messing with the balance.

  • SO WHAT DOES ALL THIS MEAN? To put it simply, as the distribution of ice and water on the

  • planet changes, the Earth's axis changes in a process called precession. Thus, the sun

  • will hit different latitudes our planet at different intensities than before -- drastically

  • changing the weather systems and our overall climate. Whether it's natural or man-made,

  • the jetstream is already shifting causing the tropical deserts to expand into previously

  • lush territory (as we know it has done in the past), but scientists don't believe this

  • is a natural phenomenon, it is happening WAY too fast, and the rates are increasing

  • we're doing this.

  • As desertification hits the American plains, South Asia, and the Mediterranean, humans

  • feel the affects through drought, climate changes, and, eventually, economics. In a

  • 2005 report about desertification from United Nations University, they state 10 to 20 percent

  • of these "drylands" have been negatively impacted through the loss of farmland and biodiversity.

  • That was a decade ago, and at the time, 2.1 billion people lived in the drylands of our

  • planet. It's clear, the deserts have, and will expand, and as they continue to do so,

  • farmland will dry, vegetation will disappear, and people will either have to move, or completely

  • alter their lifestyles.

  • Now, if you're thinking, "But Trace! The ocean is FULL of water! Let's just use that! You

  • can't. Julian explains why we can just turn saltwater to freshwater, here. (soundup)

  • REGULAR DNEWS CTA There are lots of little things that we can

  • all do to curb climate change - check out RacingExtinction.com where you can learn about

  • things like the five day carbon challenge. Challenge your friends, your family, strangers,

  • and most importantly, yourself. There's a ton of way you can do to make difference out

  • there. Thanks for watching!

  • Have you felt the pinch of climate change? How?

Desertification, is the degradation of a productive, lush environment into dry, dry desert. Great

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B1 中級

地球の砂漠は成長しており、私たちにできることは何もありません (Earth's Deserts Are Growing And There's Nothing We Can Do)

  • 153 18
    richardwang に公開 2021 年 01 月 14 日
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