WEBVTT

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[upbeat music]

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- OCEANS COVER A HUGE PART
OF OUR PLANET--

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MORE THAN 70%.

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THAT'S ALMOST 3/4 OF OUR WORLD.

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BUT NOT ALL OF THAT WATER
IS LIQUID.

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MAYBE YOU LIVE IN A PLACE
THAT GETS COLD ENOUGH TO SNOW.

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DID YOU KNOW THAT MOST
OF THE FRESHWATER

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ON OUR PLANET IS FROZEN,

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AND IN SOME PLACES,
THE WEATHER IS SO COLD

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OVER A LONG PERIOD OF TIME

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THAT THE SNOW AND ICE
NEVER MELT COMPLETELY?

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LET'S TALK TO SOMEONE AT NASA

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WHO CAN TELL US MORE ABOUT
THOSE REALLY COLD PLACES

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AND WHY NASA IS INTERESTED
IN STUDYING THEM.

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- SO WE'RE ALL FAMILIAR
WITH THE WEATHER.

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ONE DAY, IT MIGHT BE WINDY.

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ANOTHER DAY, IT MIGHT BE SUNNY

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OR MAYBE IT'S RAINY.

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THOSE WEATHER PATTERNS,
OVER A LONG PERIOD OF TIME,

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MAKE UP WHAT WE CALL CLIMATE.

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ANOTHER WAY
I LIKE TO EXPLAIN IT IS,

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CLIMATE IS WHAT YOU EXPECT,

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BUT WEATHER IS WHAT YOU GET.

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SO THE CLIMATE
ALL OVER THE WORLD

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IS DIFFERENT
IN DIFFERENT PLACES.

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NEAR THE NORTH POLE
OR THE SOUTH POLE,

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IT'S COLD YEAR-ROUND,

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AND THOSE ARE WHAT ARE CALLED
THE POLAR AREAS.

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- IT'S ICY AT THE POLES,

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AT THE NORTH POLE AS WELL
AS THE SOUTH POLE OF OUR EARTH.

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THIS IS WHERE WE HAVE
THESE WHITE ICE CAPS.

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A BIG DIFFERENCE
BETWEEN THE ARCTIC IN THE NORTH

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AND THE ANTARCTIC
IN THE SOUTH IS

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THAT THE ARCTIC,
THE NORTH POLE, IS OCEAN

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WHICH IS SURROUNDED BY LAND--

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THE UNITED STATES,
CANADA, RUSSIA--

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WHEREAS THE SOUTH POLE IS LAND
SURROUNDED BY OCEAN.

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- BUT WHAT'S SO SPECIAL
ABOUT THESE ICY PLACES, ANYWAY?

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- SO IN THE POLAR REGIONS,

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WE HAVE CONTINENTS
WHERE SNOW FALLS,

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AND IT'S SO COLD THERE
IT DOESN'T MELT IN THE SUMMER.

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AND THAT SNOW FALLS AND FALLS
AND ACCUMULATES AND ACCUMULATES,

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AND IT BUILDS UP
AND IT BUILDS UP

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AND IT BUILDS UP.

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AND THROUGH TIME,
OVER THOUSANDS OF YEARS,

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THEY MAKE WHAT WE CALL
AN ICE SHEET.

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SO ICE SHEETS ARE ICE
THAT'S ON LAND.

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- SO LAND ICE, OR ICE SHEETS,
LIKE GLACIERS AND ICEBERGS,

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FORM ON LAND.

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BUT IN PARTS
OF EARTH'S POLAR REGIONS,

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ICE COVERS OUR OCEANS.

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- SEA ICE, OR ICE
THAT'S FLOATING IN THE OCEAN,

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IS DIFFERENT.

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SEA ICE IS FORMED

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WHEN OCEAN WATER GETS COLD

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AND GETS DOWN
TO 0 DEGREES "C"

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OR 32 DEGREES FAHRENHEIT,

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AND THAT SEAWATER FREEZES.

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AND INSTEAD OF MAKING
AN ICE CUBE

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LIKE YOU SEE IN YOUR FREEZER
OR IN YOUR GLASS OF WATER,

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IT MAKES WHAT WE CALL
SEA ICE.

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- JUST LIKE AN ICE CUBE
FLOATS IN A GLASS OF WATER,

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SEA ICE FLOATS ON TOP
OF THE OCEAN.

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BUT WHETHER IT IS AN ICE SHEET
OR SEA ICE,

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SCIENTISTS HAVE BEEN
PAYING ATTENTION

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TO WHAT IS HAPPENING
TO THE ICE ON EARTH.

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IT IS MELTING FASTER
THAN THEY EXPECTED.

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SO JUST HOW DO WE WATCH
SOMETHING AS BIG

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AS EARTH'S POLAR REGIONS?

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NASA USES A SATELLITE.

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- ICE SAT-2 IS A SATELLITE

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THAT WILL BE IN ORBIT
AROUND THE EARTH,

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AND IT MEASURES THE HEIGHT
OF WHATEVER IT'S POINTED AT.

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SO FOR SEA ICE, IT WILL MEASURE
THE THICKNESS OF THE SEA ICE

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BY MEASURING THE HEIGHT
OF THE ICE SURFACE

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AND THE HEIGHT OF THE WATER
NEXT TO IT

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AND TAKING THE DIFFERENCE.

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- AND AS YOU MEASURE
THE DISTANCE

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FROM THE SATELLITE DOWN
TO THE SURFACE OF ICE,

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WE'RE ABLE TO TELL HOW THICK
THE ICE IS OVER TIME.

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AND WE'LL PASS BACK OVER
THAT PATH,

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WE KNOW WHETHER
THE ICE HAS GROWN

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OR IT HAS MELTED.

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- IN ADDITION TO THE THICKNESS
OF THE SEA ICE,

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WE CAN MEASURE THE ELEVATION
OF THE ENTIRE EARTH.

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WE MEASURE THE THIRD DIMENSION
OF OUR GLOBE.

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- BUT WHAT IS SO IMPORTANT
ABOUT EARTH'S ICE

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AND WHY DO WE CARE
HOW FAST IT MELTS?

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- ONE OF THE EASIEST WAYS
TO THINK ABOUT IT IS,

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WE HAVE A POLAR ICE CAP
IN THE ARCTIC

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WHICH COVERS MOST
OF THE ARCTIC OCEAN.

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WHEN THAT ICE BEGINS TO MELT,

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EITHER DUE TO WARM TEMPERATURES
BELOW OR ABOVE,

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THE AREA OF THE ICE
GETS SMALLER.

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AND SO THE AMOUNT OF SUNLIGHT

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THAT NORMALLY GETS REFLECTED
FROM THE ICE

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IS ACTUALLY INSTEAD ABSORBED,

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AND SO THE OCEAN TEMPERATURES
THEMSELVES HEAT UP,

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AND THAT, IN TURN, RAISES
TEMPERATURES IN THE ARCTIC,

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WHICH THEN, IN TURN, ALSO CAUSE
MORE MELTING OF THE ICE.

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BOTH THE ICE AND THE OCEANS
IN THE POLAR REGIONS

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DRIVE GLOBAL CLIMATE.

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- OKAY, SO THE OCEANS
AND THE ICE IN THEM

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HELP CONTROL THE TEMPERATURES
ON EARTH.

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AND WITH THE HELP
OF ICE SAT-2,

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NASA WILL BE ABLE TO WATCH
THE CHANGES IN ICE THICKNESS,

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AND ALL THAT INFORMATION
CAN BE USED

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TO HELP US TAKE BETTER CARE
OF OUR WORLD.