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Between September 2019 and March

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2020, wildfires killed billions of animals
and decimated more than 200,000

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square kilometers of Australian forest,
an area larger than the size of Nebraska.

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Some thousands of kilometers
away, in the Southern Ocean,

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massive algae blooms covering a surface
larger than the area of Australia itself.

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Just how are these wildfires
and ocean blooms connected?

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To untangle that,
we look to the carbon cycle.

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The carbon cycle is the flow of carbon
between reservoirs

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in the atmosphere, plants
and animals, land and ocean.

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It's one of the key processes
that keeps life sustainable on Earth.

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And at the heart of all this are land
plants and aquatic phytoplankton.

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On land, most carbon is stored in forests.

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Here, plants absorb carbon dioxide
from the atmosphere into their cells.

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With energy from the Sun

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plants combine carbon dioxide and water
to form carbohydrates, such as sugar,

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and oxygen through photosynthesis.

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In this process, carbon dioxide
is converted to carbon-based

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cellular material.

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Carbon stored in those plants
can be transferred when animals eat

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the plants, the plants die and decay,

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or, in the case of Australia, fire
consumes the plants.

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And once again, carbon based
cellular material becomes

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carbon
dioxide that ends up in the atmosphere.

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If we look to the ocean reservoir, carbon
dioxide is also absorbed

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by phytoplankton, microscopic organisms
that convert carbon dioxide, water

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and sunlight into carbohydrates like sugar
and oxygen through photosynthesis.

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Carbon
dioxide released into the atmosphere

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eventually becomes available
for aquatic photosynthesis.

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In general, any change that shifts carbon
out of one reservoir

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puts more into other reservoirs.

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But photosynthesis also requires

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nutrients
such as nitrogen, phosphorus and iron.

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Without the right proportions
of these nutrients,

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photosynthesis doesn't happen,
which can be seen in

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the iron-limited parts of the ocean,
such as far offshore of Australia.

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Atmospheric aerosols released by fires,
however, contain carbon

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as well as other nutrients
essential for plant growth like iron.

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When these aerosols are deposited
on the ocean's surface,

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these nutrients become available
for photosynthesis.

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This iron from the Australian wildfires
is now thought to have stimulated

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the massive southern Ocean phytoplankton
blooms, blooms of such magnitude

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that they converted an almost equivalent
volume of carbon dioxide

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released by the fires
into carbohydrate and cellular material.

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And here is why having a

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vantage point from space is crucial.

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From satellites, we can observe how
the movement of carbon changes

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when large scale events like wildfires
occur.

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The connection between the Australian
wildfires and Southern Ocean

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bloom could not have been made
without satellites.

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NASA's Plankton, Aerosol, Cloud, and ocean
Ecosystem, or PACE,

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mission, is specifically designed
to better measure parts of the atmosphere

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and ocean connection
with unprecedented resolution.

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PACE’s instruments will shed new light
on the composition and distribution

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of these massive mixtures of tiny aerosol
particles and aquatic microorganisms.

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Onboard are two polarimeters, instruments
that measure specific angles

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of light reflected, which, for example,
allows researchers to tease apart

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the specific type of aerosols
in these kinds of massive fire events.

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PACE’s flagship sensor, the Ocean
Color Instrument, or OCI, will cover vast

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swaths of the ocean, measuring
concentrations of photosynthetic pigments,

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allowing researchers to decipher
the different types of phytoplankton.

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With an instrument like OCI,
where you're measuring

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this full spectrum of color,
all the colors of the rainbow

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you can imagine,
we can start teasing apart the species

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and the different functional groups
and different communities that exist.

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The data from PACE
will help define those communities,

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allowing for clearer connections
within the reservoirs of the carbon cycle.

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These fires
emitted a huge amount of carbon

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and other aerosols into the atmosphere,
with some estimates suggesting volumes

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greater than Australia's annual emissions
from fire and fossil fuels combined.

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Those aerosols contained
essential nutrients that are thought

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to have stimulated the rapid growth
of phytoplankton in the Southern Ocean.

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And these kinds of connections
can have big impacts.

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It's really important to know

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where the carbon is going
and where your food source is going.

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This is important for not just climate
studies, but food security.

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The fires that tore through
Australia are just one example

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of how Earth systems are linked in ways
we're only beginning to fully understand.

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With data from PACE, we'll get a clearer
picture of carbon as it links

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land use and fires, atmospheric aerosols
and marine communities

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and ultimately improves the data
we put into climate models.