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- I can't believe how pricey
these spicy peppers were.

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Get ready for some hot facts
next on "Real World."

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[futuristic music]

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Why are some foods
more expensive than others?

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And why do some places
have more

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of one type of food
than others?

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It all boils down
to food supply

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and what plants need
in order to grow.

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- So there are many things
that a plant needs

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in order to grow.

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They need water,

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they need air,

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they need nutrients that

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they largely get
from the soil.

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They need sunlight
or sunshine.

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They need heat to grow.

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They need time, of course.
So they don't grow in one day.

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They grow through time.

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And what they do is,
they use, through their roots,

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they will carry up
the nutrients

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into the various parts
of the crop

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that will let them grow,
develop,

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and eventually
create the fruit,

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which is then what we harvest.

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All of these are what
we call natural resources.

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Our Earth provides with a lot
of natural resources,

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and all of these are really
important for life on Earth,

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whether that's human life
or the ecosystem

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and crops or animals.

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So NASA has a really important
Earth-observing fleet

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of satellites
that are continuously

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going around the world
and providing

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different types
of information.

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Satellite data
are a great tool for us

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to monitor this kind
of information

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and monitor that
on a daily basis

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to give us a global picture,

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but that can
give us information

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all the way down
at the field scale

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around how crops
are developing,

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what we can expect
the productivity is.

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And the important part then
is to convert that data

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into information
that decision-makers can use.

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So crop yields are the
harvested production

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per unit of a harvested area
of a crop.

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You know, thinking about
why is it important for us

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to measure a ton of yield.

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That's essentially giving us
the measure of productivity

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of a crop,

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and when we multiply the yield

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by the area
of where it's produced,

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that'll give us
the total production,

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which is generally--
oftentimes measured

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in tons, themselves.

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And that's giving us,
essentially,

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if we think about
what our food supply is,

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we need to care not only

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what's happening
in one country,

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but our food system
is really interconnected,

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and so it's really important
for us to understand

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actually globally
what's going on.

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So if there's a drought,
for example, in Russia,

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it's one of
the biggest exporters

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of wheat to Egypt,
and therefore, for bread.

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So if Russia has a shortfall,
right,

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if Russia produces less
than it normally would

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or less than expected,

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that has big implications
for all the people

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that are importing food
from Russia,

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and actually
has implications globally

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because when we have less food
than what we expect

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or less grain
than what we expect,

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that can have implications
also across the world

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in terms of increasing prices.

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And vice-versa,
when you have a lot of supply,

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then the prices will go down

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because you can meet
all that demand

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and more than what you have.

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- So that's the data that
NASA collects about food.

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But how do we use that data,
and what does it look like?

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- There are a lot of data sets
that come together

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to help us forecast
potential food shortages.

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The most commonly-used
band index is NDVI,

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which is Normalized Difference
Vegetation Index.

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And it tells us something

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about how healthy
the crops are

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and how green they are,

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how much chlorophyll
is in their leaves.

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So high NDVI means
really healthy crops;

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low NDVI means
very little vegetation.

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Outliers are data points

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that are
substantially different

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than the rest of the data set.

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And maybe this is
a sensor error,

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or maybe a cloud
got in the way

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and resulted
in a much different value

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than the rest of the points.

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But we also look
at other variables

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like the weather data,
which might include

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rainfall or temperature data.

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We look at soil moisture,
since healthy and moist soils

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are important for crop growth.

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The model might take in
all of this evidence

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and predict
that food production

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will be low in that region,

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and then we can then pass
that information along

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to decision makers
who can help

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to prevent or mitigate
the effects

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of the potential
food shortage.

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Even though we can observe
variables like NDVI,

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weather, and soil moisture
from space,

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we need to use
ground truth data

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to know how what we're seeing

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from space
and the satellite images

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matches up with what's
actually happening

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on the ground.

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Many people
use this information--

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farmers are always looking
to maximize their production;

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governments care about
how much food is produced,

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where the food
is being produced,

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and the economic impacts
of food production.

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Much of this data
is open source

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and available to the public
through NASA resources online.

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- Sounds like a lot of math,

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but it all adds up
to understanding

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how the world's
food supply works

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and how NASA's eyes in the sky

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can help put food
on your plate.

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[bell dings]

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Sounds like it's time for me

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to put some food on my plate.

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See you next time
on "Real World."