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Public Radio's Environmental News Magazine (follow us on Google News)

A Green Ocean

Air Date: Week of

Gene Feldman uses satellites to take pictures of the earth. The NASA scientist is especially interested in the composition of oceans and he uses the images to measure how green the water is. Producer Ari Daniel Shapiro has this profile of Feldman and his love of the green ocean.


GELLERMAN: It's Living on Earth, I'm Bruce Gellerman. From their vantage places in space, NASA satellites have kept an eye on Mother Earth for more than 50 years. The space agency’s first satellite to be used for Earth observation purposes was Explorer VII, launched in October 1959.

Producer Ari Daniel Shapiro has this profile of a NASA scientist who helped revolutionize our understanding of Earth by peering from afar.

SHAPIRO: Gene Feldman has been with NASA for over 25 years. He uses satellites to monitor and study the oceans. He’s quick to point out that sometimes a pretty picture can have a deep and lasting impact.


FELDMAN: If you think back, what’s one of the most iconic images of all time? It’s that picture of the entire Earth taken by the Apollo astronauts when they went to the Moon. The Moon pictures were fine: gray moon with craters. But what really touched the hearts of the world was that picture of the Earth, this beautiful blue and white orb dangling in the black of space from the Moon.

Feldman explaining his science to an audience.
(Photo: NASA/GSFC)

That really, really crystallized in people’s minds: one, how fragile this planet is. And more importantly, how countries and states and borders don’t mean anything. When you look at it from the vantage point of space, it’s one Earth interconnected by oceans and atmosphere.

SHAPIRO: Feldman also takes pictures of the Earth. He uses a NASA satellite that’s got an instrument called SeaWiFS. This sensor lets him keep track of the colors of the ocean.

FELDMAN: Most people think, ok, the ocean’s blue. Well, for most of the ocean, it indeed is blue. But whenever you put anything in the water, it will change the color of the ocean because it either absorbs or it reflects light differently that comes into the ocean from the sun.

And the thing that I study that impacts the color of the ocean more than anything else are microscopic plants called phytoplankton. Entire ecosystems depend on phytoplankton. Phytoplankton form the base of the food web. And without phytoplankton in the ocean, it’s safe to say there would not be life on Earth as we know it.

The global biosphere is a map of chlorophyll on land and in the ocean. (Photo: SeaWIFS Project/NASA)

And phytoplankton, because they’re plants, have this molecule called chlorophyll, which is green. And the basic idea is, the more chlorophyll you have in the water, the greener the water and the less chlorophyll, the bluer the water. So what we’re able to do from space is actually measure how green the water is.

SHAPIRO: If you had a globe in front of you and all the oceans were, say, dark and you were to take a palette of paint and start painting on it, how would you apply that paint?

FELDMAN: Before I start painting, I need to understand why different parts of the oceans would be different colors. And phytoplankton, being plants, they need certain things to grow. They need light, which there’s plenty of in the surface waters. They need nutrients, which generally is found in the deeper, colder waters in the ocean. So anytime you can bring those cold, nutrient-rich waters up near the surface, you stimulate phytoplankton growth.

So if I had my little brush in my hand, what I would do is along all of the coasts where there’s a lot of mixing and nutrient input from the land, I would paint those green. So you’ve got this green ribbon around all of the coasts. And then you’ve got places where the broad oceanic currents or wind systems stir up the waters even in the very, very deep parts. So I’d probably paint a green line along the equator. But the large central portions of the Pacific and the Atlantic – those would not be green. Those would be essentially blue because there’s not a lot of nutrients near the surface.

SHAPIRO: SeaWiFS doesn’t just measure chlorophyll in the sea. It keeps track of it on land too. So you get a picture of what Feldman likes to call…

FELDMAN: I call it the global biosphere. The Earth is not just ocean or just land or just atmosphere. All of these different pieces work together in beautiful harmony to create an environment in which life can flourish.

And when you look at these global biosphere images and more importantly, when you look at the animations over time, you can literally watch the Earth breathe. You can watch it respond to the changing seasons, to the changing location of the sun. It’s really amazing to watch the living Earth respond to the change in its environment.

SHAPIRO: In addition, Feldman and his team have been able to track how warmer temperatures in large areas of the ocean over the last decade are leading to lower phytoplankton numbers.

FELDMAN: And that has huge consequences for fisheries and for the environment.

SHAPIRO: Feldman’s global accounting of the phytoplankton and of the carbon has caught the attention of a handful of high profile people, like this guy.

Former Vice President Al Gore with SeaWIFS biosphere in lower right. (Photo: Gene Feldman)

GORE: It’s only a few kilometers to the top of the sky. And the engines of our civilization are now filling that small space with global warming pollution, as if it were an open sewer.

SHAPIRO: Back in 1999, then Senator Al Gore was interested in having a copy of Feldman’s global biosphere image. Naturally, Feldman said yes.

FELDMAN: We printed out one of these images and framed it up, and I took it down to his office. And so he jumped up on his couch and took whatever the picture was that he had behind his couch off the wall and put this one in its place. And we just sat there for a while, talking about what the colors meant and what the different patterns showed and what it meant for the kinds of things that he was doing environmentally.

[CLIP FROM INCONVENIENT TRUTH TRAILER: GORE: We have to act together to solve this global crisis. Our ability to live is what is at stake.]

SHAPIRO: Similar to Gore, Feldman feels compelled to reach out to and teach the public. But in Feldman’s case, he’s communicating his own science.

FELDMAN: I sincerely believe that part of the responsibility I have is to give back whatever it is that I’ve learned and the information that I’ve been able to gather to as broad an audience as possible. I think that our future and the future of this planet can only be made safe if people understand how the Earth works, and how we as just one creature on this planet might be impacting that.

SHAPIRO: Feldman’s giving back by offering public lectures and by going into classrooms and talking with students.


SHAPIRO: And when he’s not exploring the planet and talking to people about this blue marble that we call home, Feldman likes to spend time with his dog Max, and to play his guitar. For Living on Earth, I’m Ari Daniel Shapiro.

GELLERMAN: Our story, A Green Ocean, comes to us from Ocean Gazing, a podcast about our seas produced by COSEE - NOW, with support from the National Science Foundation. You’ll find more at our website, loe.org.



SeaWiFS Project

The Ocean Gazing podcast is produced by COSEE-NOW, the Centers for Ocean Sciences Education Excellence.


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