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[music playing]

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- We know that the energy
from the Sun

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is absorbed, reflected,

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and sent back out into space

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as part of Earth's
energy balance.

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But let's talk to
a NASA scientist

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to see what happens
if we shake things up.

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- Earth's energy balance
is very delicate,

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meaning that small changes
can have a really big impact.

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Some things
that can make small changes

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include changes in vegetation
on land,

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changing the area
of the ice caps,

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or changing the composition
of the atmosphere,

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including the amount of dust
that's in the atmosphere

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or the amount
of carbon dioxide.

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So for instance, if you change
the amount of vegetation,

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that will change the amount
of sunlight

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that is reflected
back to space.

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If you were to tear down
a forest

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and replace it with asphalt,

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you would make the surface
a lot darker,

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and so the surface
would absorb a lot more

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of the solar radiation,

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and then that would cause
the area to heat up.

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So if you reflected more solar
radiation back to space,

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Earth's energy balance
would be thrown off,

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because there would be
a lot more energy

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reflected back out to space
than is coming in.

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A volcanic eruption can spew
more ash into the atmosphere,

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and that would reflect more
solar radiation back to space,

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and this could then lead
to the ice caps growing

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and the Earth getting very,
very cold.

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If we tip the scales
the other way,

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and we cause more energy
to stay

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in the Earth's system
than to leave,

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then we would see the system
would warm.

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A very efficient way
of doing that in the past

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has been the increased carbon
dioxide in the atmosphere.

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That's caused it to get very,
very warm in the past.

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Understanding Earth's
energy balance

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is very important for climate.

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If we can understand
the factors

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that control Earth's
energy balance,

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that allows us to make
better predictions

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of our future climate,

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and making better predictions
of the future climate, then,

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will help humans thrive
and survive on planet Earth.

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- The temperatures of Earth
and all the planets

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are determined
by their energy balance.

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Just like opening a window
in the winter,

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anything that changes
the amount of energy

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coming in and going out

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disturbs the energy balance.

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But don't worry.

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Until we fully understand
the impacts

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these changes have on Earth,

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NASA will continue to keep an
eye on Earth's energy balance.

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For "Real World,"
I'm Mishay,

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and I'll see you next time.