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Hi, I'm Maria and this is NASA Now for December 7, 2011.
Today we are going to talk about climate and our oceans.
A lot of people think that global warming is just something
that happens in the atmosphere, but it turns
out that the ocean has an important role
to play in global warming.
Is there a connection and if so how?
To find out we're heading into space.
That's ahead, first here's what's happening at NASA Now.
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NASA's Operation Ice Bridge project completed another
successful mission.
Operation Ice Bridge began three years ago and was created
to survey Antarctica's changing ice.
The mission is an airborne research campaign,
where scientists fly multiple times over the Antarctic
in two planes equipped with state
of the art scientific instruments.
These instruments measure the thickness
and movement of the ice.
Data gathered helps scientists better understand changes
in climate and sea level.
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Now let's take a look at the past.
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1992, Oceanography is revolutionized
when the TOPEX/Poseidon mission provides satellite ocean
observations that aid scientists in the study
of our planet's climate.
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Over two thirds of our planet is covered with water.
It stands to reason that water must have some effect
on Earth's climate.
To bring us up to date on the latest efforts
to connect the dots between ocean levels
and climate change is Josh Willis,
from the NASA Jet Propulsion Laboratory
in Pasadena California.
The reason we need to care about sea level rise is
that we're heating up the planet
by adding greenhouse gases to the atmosphere.
As we heat up the planet, the water literally expands.
This causes sea level rise, but also melting glaciers
and ice sheets cause sea level rise as well.
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Whenever people burn fossil fuels,
we add greenhouse gases to the atmosphere.
Now, the atmosphere already has a lot of greenhouse gas
and that's the reason our planet is basically the temperature
that it is, but as we add extra greenhouse gases we actually
trap more heat on the planet.
Greenhouse gases work by allowing light from the sun
to penetrate the atmosphere, this heats up the Earth,
and then when the light tries to escape back
out into space, it gets trapped.
So, greenhouse gases keep extra energy on the planet
that would otherwise be going back out into space.
As the planet heats up, it causes things
like sea level rise, the warming of the atmosphere
and the melting of glaciers and ice sheets.
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As the planet heats up because of greenhouse gases,
we know that the majority of the heat,
80 to 90 percent is actually taken up by the oceans.
This is because the oceans have such a high heat capacity.
Heat capacity is the ability of something to take up heat
without changing its temperature and water has one
of the highest heat capacities of anything we know.
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One of the ways that we know the oceans are rising is
by measuring sea level from space.
A series of missions, called the Jason Missions,
actually measure the height of the oceans, from 800 miles
in space, by bouncing radar waves off of the ocean
and timing how long it takes for them to come back.
What these satellites tell us is that global sea level is rising.
It's rising at about a rate of one inch every decade
and we expect that rate to increase in the future.
So, measuring the oceans
from space is an extremely important part
of understanding just how much humans are changing our climate.
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Once the ocean has taken up heat or gained extra water
from melting glaciers and ice sheets, it's really hard to put
that genie back in the bottle.
It takes hundreds if not thousands of years
to reverse things like global sea level rise.
That's because getting the water out of the oceans and back
into the ice sheets takes a long time.
It's also really difficult to get heat out of the ocean
through the atmosphere and back out into space.
So, many of the things that we see today are probably going
to stay with us for a really long time to come.
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Did you know one of the greatest impacts
on human beings is climate change?
Check out this website
on the NASA Explorer Schools' Virtual Campus
where you can learn more about past civilizations
and how they were influenced.
Now it's time to check out what's up.
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The best show isn't always on TV;
instead nature will steal the show mid-December
with the Geminids meteor shower.
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One of the best ways to determine changes in weather,
or climate, is to look at data gathered
over a certain time period.
Check out this week's activity and draw your own conclusions.
There's no better way to get a feel for the weather
than creating your own weather station.
Look for this activity
on the NASA Explorer Schools' Virtual Campus
and see how you can get started.
Well that's it for NASA Now, visit our Facebook page
and tell us how you like the show.
See you next time on NASA Now.
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NASA Now comes to you from the Virtual Campus
at NASA Explorer Schools.