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NASA | Earth Science Week: The Ocean's Green Machines
Poziom:
Temat: Środowisko
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Seen from space, the blue Earth is unquestionably an ocean planet.
[Waves crash]. Standing at the shore, the ocean looks endless...and
empty. But below the surface, the ocean is actually brimming with miscroscopic
plants called phytoplankton. "If you were to take an empty
Coke can and go scoop up some water from the shore. In the Coke can
you would have between, order of 75-100 million phytoplankton in that Coke can.
This invisible forest of phytoplankon is critical to life on Earth.
Phytoplankton provide the base of the marine food web.
They also help our planet breath. Through
photosynthesis, phytoplankton generate one half of the oxygen produced on Earth that all
animals, including humans, need to breathe. [Music]
The blooms of phytoplankton also take CO2 out of the surface waters, making
the ocean an important Carbon sink. Like plants on
land, phytoplankton need sunlight, water, and nutrients to grow.
They thrive in surface waters where the sun's rays reach, and their nutrients come from many
places. Cold waters carry essential nutrients from the ocean's
lower depths to the hungry surface plants. [Music]
The trillions of phytoplankton in the ocean are critical to study. But how do researchers
track these invisible drifters? [boat sound] Ships move
too slowly for a job this big. So researchers look at global distributions of
phytoplankton from space. [Music]
Over the past decade, scientists have deployed Earth observing satellites to remotely monitor
the color of the oceans. By detecting ocean color from space, satellites
monitor the abundance of phytoplankton in the water. "The reason that it's
so important to study the phytoplankton from space is because it's the only way we can
get a perspective of actually what's happening on the entire planet, over an entire year
every day, in and out. And by doing this over many years, we can actually
see how the Earth is changing. Changing from natural forcings, natural
factors, as well as hopefully being able to detect changes that are due to human activities.
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Phyoplankton respond rapidly to envionrmental changes. In the past decade, researchers
have observed that global levels of phytoplankton tend to decrease as the ocean temperatures
warm. "During normal, physical mixing in the ocean,
nutrients come up from the bottom. Phytoplankton are fertilized; they grow;
the nutrients are depleted, the phytoplankton die or are eaten by something else.
And the process just continues. Anything that happens that
slows down that movement of cold, deep water to the surface
would stop the flow of nutrients, which would cause the phytoplankton
not to grow as well. And what's happened over the past ten years that we've been observing
the oceans, in large areas of the ocean, they've warmed up.
And what that means is the surface water has warmed,
and it has essentially put a cap on that mixing process.
[waves crash]. Music
As Earth's climate is changing, so is
the ocean. Lowered levels of phytoplankton have implications for the marine food web.
The increased CO2 in Earth's atmosphere impacts the ocean's chemistry.
The seawater becomes acidic, which threatens marine life.
"Every part of the Earth is
inerconnected with the Earth as a system. The whole Earth system.
The ocean influences the climate, the climate influences the ocean.
Land influences the ocean; all of those pieces are interconnected."
It is more important than ever to track changes in
the ocean from space, and new tools are helping researchers study the ocean and the
phytoplankton that call it home. As Earth's climate continues to
change, researchers will refine their tools and keep a close eyes on these powerful
marine plants from space. Who knew that something so small could
