WEBVTT
Kind: captions
Language: en

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Hi, this is Lyle from NASA's
Jet Propulsion Laboratory.

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Today we're going to be talking
about sea level rise

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and the way that NOAA and NASA

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are working to help us
understand changes

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that are happening in our
atmosphere and in our ocean.

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We're going to start by talking
about sea level

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and sea level rise,

00:00:27.690 --> 00:00:32.420
and we'll start by talking
about tides and water levels.

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So the first thing we need
to understand is what tides are.

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The water level of the ocean
seems to always be changing.

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Tides appear as the regular
rise and fall

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of the sea surface.

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This animation shows
the relationship

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between the vertical and
horizontal components of tides.

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As the tide rises,
water moves toward the shore.

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This is called a flood current.

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As the tide recedes,
water moves away from the shore.

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This is called an ebb current.

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The movement of water toward
and away from the shore

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is illustrated by the movement
of the green seaweed.

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Tides are actually
long-period waves

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that move through the ocean

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in response to the
gravitational forces

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exerted by the moon
and the sun.

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Here we see the moon
and Earth,

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and we're looking at Earth
from the North Pole.

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You can see that red dot
that represents the North Pole.

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There are two yellow dots.

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One represents me here
in California,

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and the other one is on the
east coast of the United States.

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And gravity from the moon
pulls on the ocean,

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creating a bulge of water
on one side of Earth.

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While the Earth rotates about
a common center of gravity

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between Earth and the moon,
it wobbles and creates a bulge

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on the opposite side of Earth.

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As Earth rotates,
places on the surface

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will move through these
high tide and low tide regions.

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Here's an example
of sea level changing

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between high tide and low tide.

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You'll notice on the left,
during low tide,

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much more of the beach
is visible

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as well as more of the bottom
of the pier,

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while on the right side,
less of the beach is visible

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and more of the pier supports
are covered by water.

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The line of debris on this beach
marks the extent of high tide.

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There are multiple debris lines

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from high tides
of differing heights.

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Sea level is measured
and recorded

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at monitoring stations
around the world.

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Here you can see an example
of a simple monitoring station,

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while here you can see
what is called

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a sentinel monitoring station.

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The sentinel looks different

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because it is built to withstand
a category 4 hurricane.

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In addition to sea level
monitoring stations,

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we measure sea level
with satellites.

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This allows us to get
a global picture of sea level.

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We verify our satellite
measurements

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with the ground stations.

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This is done using radar.

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A satellite sends a radar signal
towards the surface of the ocean

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and times how long it takes
for that signal to return.

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In this global image,
you can see

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areas of higher water in brown
and lower water in blue.

00:03:03.810 --> 00:03:06.810
This monthly tide chart
shows the difference

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between high and low tide
during one month

00:03:09.330 --> 00:03:11.030
at Battery Park in New York.

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These are normal changes
in the sea level

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that we expect to see
on a daily and monthly basis.

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The blue line shows
the predicted tide levels,

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and the red line shows
what was measured.

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In October of 2014,

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the first quarter and
last quarter moon phases

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came at the beginning
and the middle of the month.

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During those times,
we experienced

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higher low tides
and lower high tides,

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while the full moon and new moon
fell on the 8th and 24th.

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During those times,
we experienced

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higher high tides
and lower low tides.

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So why do we measure
and predict water levels?

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I'll give you a moment
to think about that.

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The NOAA air gap system is a
tool that measures the clearance

00:03:54.810 --> 00:03:57.270
between the water surface
and the bridge.

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Air gap measurements are updated
every six minutes

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to account for changes in the
water level and bridge height

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due to traffic, air temperature,
and other factors.

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Data on the air gap,
along with real-time data

00:04:08.840 --> 00:04:11.810
on water conditions like
tides, currents, and winds

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help ship captains safely enter
and leave U.S. ports.

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This information is critical
for ship captains

00:04:17.690 --> 00:04:20.390
to safely navigate a ship
under a bridge.

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Hereyou can see
theUSS New York

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clearing the Huey P. Long Bridge

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on June 27th of 2009,

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by a margin of only 2.1 feet.

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In addition to knowing water
levels for the air gap system,

00:04:40.120 --> 00:04:42.750
predicting storm surge
is also important.

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Storm surge is water
from the ocean

00:04:44.780 --> 00:04:46.240
that is pushed toward the shore

00:04:46.300 --> 00:04:48.720
by the force of the winds
swirling around a hurricane

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or a storm.

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Here you can see how having
water level information

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allowed storm surge warnings
to be made

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before Superstorm Sandy
approached the Northeast.

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This allowed people to evacuate
affected areas

00:05:04.000 --> 00:05:06.780
before the storm arrived,
potentially saving many lives.

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You can see here how storm surge
impacted an area

00:05:09.810 --> 00:05:12.480
along the east coast
after the storm.

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The rise and fall of the tides
on a daily basis

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and the changes
on a monthly basis

00:05:17.870 --> 00:05:20.030
are something that
we expect to see.

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Now we're going to talk
about sea level rise.

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NOAA calculates relative
sea level trends

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at U.S. and global stations

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for local, regional, and global
trend comparisons

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generated from water level
observations

00:05:32.210 --> 00:05:34.750
collected for a minimum
of 30 years

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from 128 U.S. and 240 global
long-term water level stations.

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When looking at this map,

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what do you notice about
sea level trends?

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You may see that around
most areas in the U.S.,

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sea level is rising.

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This map shows sea level
indicators for Baltimore.

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The yellow arrow indicates

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that sea level in this area
is rising.

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This is an example of
mean sea level measured

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at one of the oldest U.S.
tidal stations in Baltimore

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from 1902 to 2006.

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By looking at this graph
of the last 104 years,

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you can see that
mean sea level has risen

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approximately 35 centimeters,
or 13 inches.

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Earth is a water planet

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with 70% of its surface
covered by water.

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This image is meant
to illustrate

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that while we call
our planet Earth

00:06:22.570 --> 00:06:24.570
and typically look at views
of the planet

00:06:24.630 --> 00:06:26.420
with a focus on the continents,

00:06:26.480 --> 00:06:29.600
it is mostly covered
with water.

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We saw that sea level was rising
in Baltimore,

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but what about sea level rise
on a global scale?

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If you saw data that
looked like this,

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what would you do with it?

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We looked at one location,
Maryland,

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and saw evidence
of sea level rise.

00:06:51.690 --> 00:06:53.480
But to know if it's happening
worldwide,

00:06:53.540 --> 00:06:55.600
we need to look at data
from many locations

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and get an understanding of
what is happening to sea level

00:06:58.000 --> 00:06:59.630
on a global scale.

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The data that you see here
is a measurement

00:07:02.120 --> 00:07:07.810
of global mean sea level change
from each year, 1993-2009.

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I want you to take a moment
and plot these data points

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and look for any trends
or patterns that you see.

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You might have noticed
that your data points

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don't line up nicely
to create a linear graph,

00:07:23.750 --> 00:07:26.750
but they do suggest a trend
in the rise of sea level.

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By looking at this data,

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we can see that sea level
on a global scale is rising.

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What might account
for the nonlinear graph?

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Global sea level rise
has changed

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over the past 400,000 years.

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It has varied substantially
over history,

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especially in response
to the Ice Ages.

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But in recent history,
circled in red,

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it has been pretty steady.

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Starting around 7,000 years ago,
sea level became quite steady --

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again, the area circled in red.

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But over the last century,
sea level has been rising.

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Global tide gauge measurements
from tide gauges

00:08:05.720 --> 00:08:07.660
suggests the global
sea level rose

00:08:07.720 --> 00:08:12.240
approximately 1.8 millimeters
per year over the last century.

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All of the areas you see
highlighted in red

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are at risk due to
sea level rise.

00:08:16.780 --> 00:08:19.000
We've had roughly a foot
of sea level rise

00:08:19.060 --> 00:08:21.120
in New York City
in the past century.

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That's measured at a tidal gauge
near Battery Park,

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just off the southern tip
of Manhattan.

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The total amount of water
on Earth isn't increasing,

00:08:30.030 --> 00:08:32.870
but the volume of liquid
that fills the ocean basins

00:08:33.030 --> 00:08:36.210
is growing, raising the
elevation of the sea's surface

00:08:36.270 --> 00:08:39.150
and spilling ocean water
onto low-lying land.

00:08:39.210 --> 00:08:41.810
So, what is causing
the increase?

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The extra volume of seawater
comes from two places.

00:08:48.840 --> 00:08:51.510
Clearly, melting of ice sheets
and glaciers on land

00:08:51.570 --> 00:08:53.870
adds more water to the sea.

00:08:54.030 --> 00:08:57.270
Less obviously, water expands
as it warms,

00:08:57.330 --> 00:08:59.870
so the more heat energy
the ocean absorbs,

00:09:00.090 --> 00:09:02.690
the more space its water
requires.

00:09:02.750 --> 00:09:04.660
Global sea level
is currently rising

00:09:04.720 --> 00:09:07.570
as a result of both
ocean thermal expansion

00:09:07.630 --> 00:09:11.180
and glacier melt, with each
accounting for about half

00:09:11.240 --> 00:09:13.060
of the observed sea level rise

00:09:13.120 --> 00:09:15.330
and each caused
by recent increases

00:09:15.390 --> 00:09:17.390
in global mean temperatures.

00:09:17.450 --> 00:09:20.000
From 1961 to 2003,

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sea level rose due to thermal
expansion and glacier melt

00:09:23.330 --> 00:09:26.750
at a rate of about
1.11 millimeters per year.

00:09:26.810 --> 00:09:29.780
Between 1993 and 2003,

00:09:29.840 --> 00:09:31.630
the contribution
to sea level rise

00:09:31.690 --> 00:09:36.150
increased from both sources
to 2.79 millimeters per year.

00:09:36.210 --> 00:09:38.210
So not only is sea level rising,

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it is rising at a faster rate
than in the past.

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Now what I'd like to do
is take a closer look

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at the causes of sea level rise,

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both ice melt
and thermal expansion.

00:09:49.300 --> 00:09:52.030
Here you can see the measured
mass of glaciers declining

00:09:52.090 --> 00:09:54.360
as they have melted over
the past several decades.

00:09:54.420 --> 00:09:56.720
Like other data, the graphs
aren't straight lines,

00:09:56.780 --> 00:09:59.120
but you can see trends
in what's happening.

00:09:59.180 --> 00:10:01.240
Where do you think the largest
ice sheets and glaciers

00:10:01.300 --> 00:10:02.750
are found?

00:10:08.030 --> 00:10:10.390
The largest glaciers
and ice sheets are found

00:10:10.450 --> 00:10:12.480
in Greenland and Antarctica.

00:10:12.540 --> 00:10:14.570
Here we can see
the Greenland ice sheet

00:10:14.630 --> 00:10:16.630
and its measured mass declining.

00:10:16.690 --> 00:10:18.570
Here we can see
the reduction in mass

00:10:18.630 --> 00:10:21.360
of the West Antarctic ice sheet
as it has melted.

00:10:21.420 --> 00:10:24.210
These two regions,
Greenland and Antarctica,

00:10:24.270 --> 00:10:27.330
have the potential to cause
a great rise in sea level

00:10:27.390 --> 00:10:29.030
if they were to fully melt.

00:10:29.090 --> 00:10:31.270
If the Greenland ice sheet
completely melted,

00:10:31.330 --> 00:10:33.330
we would see a rise of 7 meters.

00:10:33.390 --> 00:10:35.510
If West Antarctica's ice sheet
melted,

00:10:35.570 --> 00:10:38.840
it would be an additional
7 meters of sea level rise.

00:10:39.000 --> 00:10:41.300
If the East Antarctica
ice sheet melted,

00:10:41.360 --> 00:10:44.540
it would result in 70 meters
of sea level rise.

00:10:44.600 --> 00:10:46.870
However, the most significant
contributors

00:10:47.030 --> 00:10:49.210
to sea level rise
within the current climate

00:10:49.270 --> 00:10:51.870
are not the Greenland
and Antarctic ice sheets.

00:10:52.030 --> 00:10:53.690
What are they?

00:10:57.420 --> 00:11:00.120
The mass balance for
the Antarctic ice sheet

00:11:00.180 --> 00:11:03.420
may represent only about 10%
of the current contribution

00:11:03.480 --> 00:11:06.270
to sea level rise
coming from glaciers.

00:11:06.330 --> 00:11:09.630
The Greenland ice sheet may be
contributing about 30%

00:11:09.690 --> 00:11:12.120
of all glacier melt
to sea level rise.

00:11:12.180 --> 00:11:15.030
That means Greenland and
Antarctica only account for

00:11:15.090 --> 00:11:19.600
about 40% of sea level rise
coming from ice melt.

00:11:19.660 --> 00:11:21.360
In contrast to polar regions,

00:11:21.420 --> 00:11:24.720
the network of lower latitude
small glaciers and ice caps,

00:11:24.780 --> 00:11:28.870
although making up only about 4%
of the total land ice area,

00:11:29.030 --> 00:11:32.030
or about 760,000 square
kilometers,

00:11:32.090 --> 00:11:34.360
may have provided as much as 60%

00:11:34.420 --> 00:11:37.390
of the total glacier
contribution to sea level change

00:11:37.450 --> 00:11:39.360
since the 1990s.

00:11:39.420 --> 00:11:41.660
The contribution
to sea level rise

00:11:41.720 --> 00:11:44.330
from lower latitude ice caps
and glaciers

00:11:44.390 --> 00:11:47.060
is apparent in these
before and after pictures

00:11:47.120 --> 00:11:50.120
of Lillian Glacier
in Olympic National Park.

00:11:50.180 --> 00:11:52.660
This first image was taken
in 1905.

00:11:52.720 --> 00:11:55.780
Note the red arrows marking
the boundaries of glaciers.

00:11:55.840 --> 00:11:59.330
Compared with a picture
taken in 2010.

00:11:59.390 --> 00:12:01.240
You can see the red arrows

00:12:01.300 --> 00:12:03.720
indicating the former extent
of the glacier.

00:12:03.780 --> 00:12:06.300
Anderson Glacier
is a similar example.

00:12:06.360 --> 00:12:08.810
Again, note the extent
of the edge of the glacier,

00:12:08.870 --> 00:12:13.270
marked by the red arrows
in this picture taken in 1936.

00:12:13.330 --> 00:12:16.750
And compare that with a picture
taken in 2004.

00:12:16.810 --> 00:12:19.270
We talked about glaciers,
which are on land,

00:12:19.330 --> 00:12:21.690
but not about sea ice.
Why not?

00:12:21.750 --> 00:12:25.090
Well, sea ice displaces water,
and as it melts,

00:12:25.150 --> 00:12:27.120
does not contribute
to sea level rise.

00:12:27.180 --> 00:12:29.150
You can see this melting
ice block

00:12:29.210 --> 00:12:31.720
does not add to the volume,

00:12:31.780 --> 00:12:34.240
and thus does not raise
the sea level.

00:12:34.300 --> 00:12:36.090
Glaciers, however,
when they melt,

00:12:36.150 --> 00:12:40.330
add water to the ocean basins,
thus raising sea level.

00:12:40.390 --> 00:12:43.180
As we discussed before,
glacier and ice sheet melt

00:12:43.240 --> 00:12:46.090
is only part of the reason
ocean level is rising.

00:12:46.150 --> 00:12:48.210
As fluids such as water
are heated,

00:12:48.270 --> 00:12:50.210
they want to maintain
a constant pressure.

00:12:50.270 --> 00:12:53.270
In order to do that, they expand
and increase in volume.

00:12:53.330 --> 00:12:54.810
That's thermal expansion.

00:12:54.870 --> 00:12:57.420
In the ocean, that results
in sea level rise.

00:12:57.480 --> 00:12:59.600
In this system, when
the heat lamp is turned on

00:12:59.660 --> 00:13:01.630
and the water increases
in temperature,

00:13:01.690 --> 00:13:04.540
the increase in volume
will cause the water

00:13:04.600 --> 00:13:07.630
to be pushed up
through the straw.

00:13:15.270 --> 00:13:20.060
Annually, we observe a sea level
rise of about 3.1 millimeters.

00:13:20.120 --> 00:13:24.090
0.2 millimeters comes from
the Greenland ice sheet melt.

00:13:24.150 --> 00:13:28.120
Another 0.2 millimeters comes
from Antarctic ice sheet melt.

00:13:28.180 --> 00:13:32.420
0.8 millimeters comes from
glaciers and ice cap melt,

00:13:32.480 --> 00:13:35.600
while nearly half,
1.6 millimeters,

00:13:35.660 --> 00:13:38.840
comes from ocean thermal
expansion.

00:13:39.000 --> 00:13:41.660
This means the water
is heating up.

00:13:41.720 --> 00:13:43.630
Where is the heat coming from?

00:13:49.330 --> 00:13:51.720
Satellites and weather stations
on land show

00:13:51.780 --> 00:13:54.690
that average air temperature
at the surface is going up.

00:13:54.750 --> 00:13:58.000
Consequently, we see an increase
in the number of heat waves

00:13:58.060 --> 00:14:00.720
and the area affected
by drought.

00:14:00.780 --> 00:14:03.120
Thermometers on ships
and floating buoys

00:14:03.180 --> 00:14:05.060
show that air near
the ocean surface

00:14:05.120 --> 00:14:06.630
is getting warmer as well,

00:14:06.690 --> 00:14:09.270
increasing its ability
to evaporate water.

00:14:09.330 --> 00:14:12.360
In turn, we see an increase
in heavy precipitation events

00:14:12.420 --> 00:14:14.360
and flooding on land.

00:14:14.420 --> 00:14:16.690
Measurements from satellite
and weather balloons

00:14:16.750 --> 00:14:19.120
show that the lowest layer
of the atmosphere,

00:14:19.180 --> 00:14:22.060
where we live,
where airplanes fly,

00:14:22.120 --> 00:14:24.660
and where weather occurs,
is warming.

00:14:24.720 --> 00:14:27.120
Greenhouse gases are building
in this layer,

00:14:27.180 --> 00:14:29.690
trapping heat radiated
from Earth's surface,

00:14:29.750 --> 00:14:31.480
and raising the planet's
temperature.

00:14:31.540 --> 00:14:34.600
Satellite sensors and
thermometers on ships and buoys

00:14:34.660 --> 00:14:36.150
show that the temperature
of water

00:14:36.210 --> 00:14:38.180
at the ocean's surface
is rising.

00:14:38.240 --> 00:14:40.450
Warm surface waters can damage
coral reefs,

00:14:40.510 --> 00:14:43.150
reducing opportunities
for fishing and tourism,

00:14:43.210 --> 00:14:47.120
and leave coasts vulnerable
to storm surges and erosion.

00:14:47.180 --> 00:14:50.510
It turns out the ocean
can absorb a lot of heat,

00:14:50.570 --> 00:14:54.420
and as a result, those increases
in air temperature we just saw

00:14:54.480 --> 00:14:57.000
lead to an increased
water temperature.

00:14:57.060 --> 00:14:59.570
Let's take a look at how it's
able to absorb so much heat.

00:14:59.630 --> 00:15:01.420
I have a guest here
with me today

00:15:01.480 --> 00:15:03.510
that can tell us a lot more
about climate change,

00:15:03.570 --> 00:15:04.870
Josh Willis.

00:15:05.030 --> 00:15:07.030
Now, you're an oceanographer
here at JPL, correct?

00:15:07.090 --> 00:15:09.630
Well, I'm an oceanographer,
but I study sea level rise

00:15:09.690 --> 00:15:12.510
and global warming and really
how the ocean fits into

00:15:12.570 --> 00:15:14.330
that whole global warming
picture.

00:15:14.390 --> 00:15:17.840
It turns out that 80% to 90%
of the heat from global warming

00:15:18.000 --> 00:15:19.690
is actually going
into the oceans.

00:15:19.750 --> 00:15:22.810
So the oceans are really
the big Earth heat bucket.

00:15:22.870 --> 00:15:25.000
That's where all the heat
winds up going.

00:15:25.060 --> 00:15:26.510
The oceans can absorb

00:15:26.570 --> 00:15:29.180
1,000 times the amount of heat
as the atmosphere

00:15:29.240 --> 00:15:31.300
without really changing their
temperature all that much.

00:15:31.360 --> 00:15:34.870
And the reason is because of
something called heat capacity.

00:15:35.030 --> 00:15:36.630
Let's imagine that
this balloon represents

00:15:36.690 --> 00:15:38.270
the whole Earth's atmosphere.

00:15:38.330 --> 00:15:42.450
So now my candle, my little
lighter here represents the sun,

00:15:42.510 --> 00:15:44.840
so let's add some heat to it
and see what happens.

00:15:46.750 --> 00:15:48.030
Whoa!

00:15:48.090 --> 00:15:52.030
So obviously the heat capacity
of air is very low

00:15:52.090 --> 00:15:53.810
because it didn't absorb
any heat at all.

00:15:53.870 --> 00:15:55.180
That's right.

00:15:55.240 --> 00:15:57.030
Almost as soon as we put
the candle to the balloon,

00:15:57.090 --> 00:15:58.840
it exploded, and the reason
is because

00:15:59.000 --> 00:16:01.000
since the air inside the balloon

00:16:01.060 --> 00:16:02.660
couldn't really absorb the heat
that fast,

00:16:02.720 --> 00:16:05.180
all the heat went toward
melting the rubber.

00:16:05.240 --> 00:16:07.000
As soon as the rubber melted,
the balloon explodes.

00:16:07.060 --> 00:16:08.420
Ah, okay, cool.

00:16:08.480 --> 00:16:10.720
Now that's a good demonstration
of the heat capacity of air.

00:16:10.780 --> 00:16:13.240
How about the heat capacity
of water or the oceans?

00:16:13.300 --> 00:16:14.540
Yeah, let's do the oceans.

00:16:14.600 --> 00:16:15.630
How about a water balloon,
Steve?

00:16:15.690 --> 00:16:18.030
- Sounds great.
- All right.

00:16:18.090 --> 00:16:20.210
All right, Steve, so this
balloon filled with water

00:16:20.270 --> 00:16:21.780
represents the oceans,

00:16:21.840 --> 00:16:24.300
and my lighter here
represents the sun.

00:16:24.360 --> 00:16:28.030
Let's put some heat on it
and see what happens.

00:16:28.090 --> 00:16:30.030
Wow.

00:16:30.090 --> 00:16:32.360
Obviously it's absorbing
a great deal of heat.

00:16:32.420 --> 00:16:34.330
Right, so you feeling the heat
there, Steve?

00:16:34.390 --> 00:16:35.660
I am.

00:16:35.720 --> 00:16:37.180
All right, the balloon
really isn't,

00:16:37.240 --> 00:16:40.690
because it turns out that the
water can absorb so much heat

00:16:40.750 --> 00:16:44.300
that it takes the heat away
from the skin of the balloon

00:16:44.360 --> 00:16:46.780
before the rubber can melt,
so the balloon doesn't pop.

00:16:46.840 --> 00:16:48.300
Excellent example.

00:16:48.360 --> 00:16:51.240
So the water has a tremendous
ability to absorb heat,

00:16:51.300 --> 00:16:53.390
and if that's an analog
for our oceans,

00:16:53.450 --> 00:16:55.690
that means our oceans are
absorbing a lot of heat as well.

00:16:55.750 --> 00:16:57.360
That's right.
They sure are, Steve.

00:16:57.420 --> 00:17:00.120
LYLE: As global temperatures
warm, scientists expect

00:17:00.180 --> 00:17:02.660
that the rate of sea level rise
will increase.

00:17:02.720 --> 00:17:05.240
Researchers are working
to unravel the details

00:17:05.300 --> 00:17:08.210
that will allow them to predict
how much the seawater

00:17:08.270 --> 00:17:11.300
at different depths in the ocean
will warm and expand.

00:17:11.360 --> 00:17:13.690
Scientists are also working
to understand

00:17:13.750 --> 00:17:17.180
how ice sheets on Greenland
and Antarctica will react

00:17:17.240 --> 00:17:18.840
to higher global temperatures.

00:17:19.000 --> 00:17:21.360
If the downhill motion of these
ice sheets accelerates,

00:17:21.420 --> 00:17:23.390
sea level could rise abruptly.

00:17:23.450 --> 00:17:25.780
So where is this heat
coming from?

00:17:29.870 --> 00:17:32.390
Since the beginning
of the Industrial Revolution,

00:17:32.450 --> 00:17:35.030
the concentration of carbon
dioxide in the atmosphere

00:17:35.090 --> 00:17:37.210
has increased by 39%.

00:17:37.270 --> 00:17:39.720
Some of this extra carbon
dioxide has been absorbed

00:17:39.780 --> 00:17:42.060
by oceans, soils, and trees,

00:17:42.120 --> 00:17:43.660
but the rest will stay
in the atmosphere

00:17:43.720 --> 00:17:45.390
for thousands of years.

00:17:45.450 --> 00:17:47.540
This is significant
for our climate,

00:17:47.600 --> 00:17:50.330
because carbon dioxide is
the most important gas

00:17:50.390 --> 00:17:53.000
for controlling Earth's
atmospheric temperature.

00:17:53.060 --> 00:17:55.630
Carbon dioxide and other
atmospheric gases

00:17:55.690 --> 00:17:58.810
control Earth's temperature
through the greenhouse effect.

00:17:58.870 --> 00:18:02.090
Without a greenhouse effect,
the temperature on Earth

00:18:02.150 --> 00:18:04.630
would be much colder
than it is now.

00:18:04.690 --> 00:18:07.840
But an increase in CO2
traps heat in the atmosphere,

00:18:08.000 --> 00:18:11.240
leading to the increases
in temperature that we've seen.

00:18:11.300 --> 00:18:15.180
So, what is the source
of this additional CO2?

00:18:18.090 --> 00:18:20.840
A majority of CO2 is created
by energy production

00:18:21.000 --> 00:18:22.870
from fossil fuels
that we are demanding

00:18:23.030 --> 00:18:24.630
to support our lifestyles.

00:18:24.690 --> 00:18:26.810
Automobile traffic, air travel,

00:18:26.870 --> 00:18:30.330
and coal and natural gas
power plants are contributors.

00:18:30.390 --> 00:18:33.030
Before we look at some of
the impacts of rising sea level,

00:18:33.090 --> 00:18:36.000
what do you think some of
the potential impacts are?

00:18:40.360 --> 00:18:42.030
Let's think about New York City,

00:18:42.090 --> 00:18:44.000
the most populated city
in the United States,

00:18:44.060 --> 00:18:46.660
with over 8.4 million residents
living there.

00:18:46.720 --> 00:18:48.840
Now imagine this.

00:18:49.000 --> 00:18:51.660
With 28 centimeters, or 11
inches, of sea level rise

00:18:51.720 --> 00:18:55.120
predicted by the 2020s,
there's a 1% chance of flooding

00:18:55.180 --> 00:18:57.420
in the dark blue areas
every year.

00:18:57.480 --> 00:19:00.510
And with 79 centimeters, or
31 inches, of sea level rise

00:19:00.570 --> 00:19:02.300
predicted by the 2050s,

00:19:02.360 --> 00:19:04.180
there's a 1% chance of flooding

00:19:04.240 --> 00:19:06.690
into the light blue areas
every year,

00:19:06.750 --> 00:19:10.060
impacting a huge number
of people and businesses.

00:19:10.120 --> 00:19:13.390
In addition to sea level rise
impacting New York City,

00:19:13.450 --> 00:19:16.030
the southeastern United States
faces a great risk

00:19:16.090 --> 00:19:17.450
from sea level rise.

00:19:17.510 --> 00:19:19.240
Watch how much land
is covered by water

00:19:19.300 --> 00:19:21.450
with a 5-foot rise in sea level,

00:19:21.510 --> 00:19:23.360
a 10-foot rise in sea level,

00:19:23.420 --> 00:19:25.540
or a 15-foot rise in sea level.

00:19:25.600 --> 00:19:28.810
Now imagine a 20-foot rise
in sea level.

00:19:28.870 --> 00:19:32.060
Sea level rise is already
impacting some coastal areas.

00:19:32.120 --> 00:19:34.690
Here you can see a home
that has been made unlivable

00:19:34.750 --> 00:19:37.030
as higher and higher sea level
has eroded away

00:19:37.090 --> 00:19:39.450
the surrounding ground,
exposing septic tanks

00:19:39.510 --> 00:19:41.420
and washing away
building supports.

00:19:41.480 --> 00:19:45.090
In American Samoa, there is only
a small amount of land

00:19:45.150 --> 00:19:48.060
between the steep mountains
and the water's edge,

00:19:48.120 --> 00:19:50.540
so you can't just back up
a village a few hundred feet

00:19:50.600 --> 00:19:53.000
when the sea level rises
and be okay.

00:19:53.060 --> 00:19:56.000
In landscapes like this,
you quickly lose usable land

00:19:56.060 --> 00:19:57.690
with sea level rise.

00:19:57.750 --> 00:20:01.000
This is a small village
in American Samoa

00:20:01.060 --> 00:20:04.510
that will suffer major impacts
with sea level rise.

00:20:04.570 --> 00:20:07.360
American Samoa shows
the severeness of the issue,

00:20:07.420 --> 00:20:10.240
especially since there is
nowhere for people to go.

00:20:10.300 --> 00:20:12.810
The light blue line shows
the current shorelines,

00:20:12.870 --> 00:20:15.510
and the dark blue shows
land, streets, and houses

00:20:15.570 --> 00:20:18.030
that will be covered
by a rising ocean.

00:20:18.090 --> 00:20:20.630
In this simulation,
note the sea wall here

00:20:20.690 --> 00:20:23.120
that's used to protect
against storm surge.

00:20:23.180 --> 00:20:26.120
With a simulated sea level rise,
you can see there's no longer

00:20:26.180 --> 00:20:28.090
any protection for those houses

00:20:28.150 --> 00:20:30.810
when it comes to an approaching
storm surge.

00:20:30.870 --> 00:20:33.180
As relative sea level rise
increases,

00:20:33.240 --> 00:20:35.570
it no longer takes
a strong storm or a hurricane

00:20:35.630 --> 00:20:37.240
to cause coastal flooding.

00:20:37.300 --> 00:20:39.780
Flooding now occurs with
high tides in many locations

00:20:39.840 --> 00:20:42.090
due to climate-related
sea level rise,

00:20:42.150 --> 00:20:45.240
land subsidence, and the loss
of natural barriers.

00:20:45.300 --> 00:20:48.510
Nuisance flooding, which causes
such public inconveniences

00:20:48.570 --> 00:20:51.690
as frequent road closures,
overwhelmed storm drains,

00:20:51.750 --> 00:20:53.600
and compromised infrastructure,

00:20:53.660 --> 00:20:56.420
has increased on
all three U.S. coasts

00:20:56.480 --> 00:21:01.240
between 300% and 925%
since 1960.

00:21:01.300 --> 00:21:03.540
The effect of rising sea levels

00:21:03.600 --> 00:21:05.840
along most of the continental
U.S. coastline

00:21:06.000 --> 00:21:07.720
are expected to become
more noticeable

00:21:07.780 --> 00:21:09.810
and much more severe
in the coming decades,

00:21:09.870 --> 00:21:13.660
likely more so than any other
climate change-related factor.

00:21:13.720 --> 00:21:16.120
Any acceleration
in sea level rise

00:21:16.180 --> 00:21:18.120
that is predicted to occur
this century

00:21:18.180 --> 00:21:21.210
will further intensify nuisance
flooding impacts over time

00:21:21.270 --> 00:21:24.780
and will further reduce the time
between flood events.

00:21:24.840 --> 00:21:27.660
The city of Norfolk, Virginia,
is already experiencing

00:21:27.720 --> 00:21:29.480
the effects of sea level rise.

00:21:29.540 --> 00:21:31.630
Streets that used to flood
only occasionally

00:21:31.690 --> 00:21:34.690
now fill with seawater
every time there's a full moon.

00:21:34.750 --> 00:21:37.540
The Federated States
of Micronesia in the Pacific

00:21:37.600 --> 00:21:40.630
has 30,000 citizens living
on atolls that are vanishing

00:21:40.690 --> 00:21:42.870
due to sea level rise
from climate change.

00:21:43.030 --> 00:21:45.060
Today they have drinking water
shortages,

00:21:45.120 --> 00:21:47.420
and food security is in peril.

00:21:47.480 --> 00:21:50.270
The population of coastal
watershed counties

00:21:50.330 --> 00:21:53.030
in the U.S. and territories,
including the Great Lakes,

00:21:53.090 --> 00:21:56.000
makes up more than 50%
of the nation's population

00:21:56.060 --> 00:21:58.690
and contributed more than
$8.3 trillion

00:21:58.750 --> 00:22:01.120
to the 2011 U.S. economy,

00:22:01.180 --> 00:22:03.540
but depend on healthy coasts.

00:22:03.600 --> 00:22:06.270
Expected health impacts
of sea level rise

00:22:06.330 --> 00:22:08.270
include a decline
in seafood quality,

00:22:08.330 --> 00:22:10.060
shifts in disease patterns,

00:22:10.120 --> 00:22:13.240
and increases in rates
of heat-related morbidity.

00:22:13.300 --> 00:22:15.270
So let's review.

00:22:15.330 --> 00:22:18.150
By monitoring, we know
that sea level is rising.

00:22:18.210 --> 00:22:20.840
It's rising due to ice melt
being added to the oceans

00:22:21.000 --> 00:22:24.180
but also because of thermal
expansion of water.

00:22:24.240 --> 00:22:26.600
Ice is melting and water
is expanding

00:22:26.660 --> 00:22:28.510
because of increased
temperatures.

00:22:28.570 --> 00:22:30.210
Increased temperatures
are connected

00:22:30.270 --> 00:22:32.600
to a rise in CO2
in the atmosphere,

00:22:32.660 --> 00:22:36.690
and a rise in CO2 is linked
to human activity.

00:22:36.750 --> 00:22:38.870
So what can we do about it?

00:22:42.540 --> 00:22:45.480
We use energy to heat
and cool our homes.

00:22:45.540 --> 00:22:47.420
Moderating thermostats,

00:22:47.480 --> 00:22:49.420
insulating homes
as much as possible

00:22:49.480 --> 00:22:52.330
can help reduce the increase
of CO2.

00:22:52.390 --> 00:22:54.690
We use electricity
to power appliances.

00:22:54.750 --> 00:22:56.480
Think about what's being
left on

00:22:56.540 --> 00:22:58.630
and being turned off
when you leave the house.

00:22:58.690 --> 00:23:00.330
Consider phantom charges

00:23:00.390 --> 00:23:03.300
and using a power strip
to turn off appliances.

00:23:03.360 --> 00:23:05.390
We use cars for the majority
of travel

00:23:05.450 --> 00:23:08.510
rather than taking public
transportation, carpooling,

00:23:08.570 --> 00:23:12.180
or using alternative transport
such as bikes or walking.

00:23:12.240 --> 00:23:15.330
So those are some of the things
that can be done,

00:23:15.390 --> 00:23:17.570
but be thinking about
what else can be done

00:23:17.630 --> 00:23:19.570
and who else can make
a difference.

00:23:19.630 --> 00:23:21.390
For one of your follow-up
activities,

00:23:21.450 --> 00:23:23.150
you'll be calculating
your carbon footprint

00:23:23.210 --> 00:23:26.390
to see how much carbon you're
contributing to the environment.

00:23:26.450 --> 00:23:28.210
Thanks for joining me today.

00:23:28.270 --> 00:23:30.300
From all of us at NOAA, NASA,

00:23:30.360 --> 00:23:31.690
and the Jet Propulsion
Laboratory,

00:23:31.750 --> 00:23:33.090
have a great rest of your day.

00:23:33.150 --> 00:23:34.420
Bye-bye.