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Phytoplankton monitoring under threat -

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Robyn Williams: Some key satellites tracking the health of the oceans are soon to die. This is
Michael Behrenfeld from Oregon.

Michael Behrenfeld: Satellites are one of the most important tools we have for studying the life of
the ocean. What we do with these satellites largely is focus on the plants, they're called
phytoplankton and they're microscopic. Phytoplankton is absolutely essential to the health of this
planet. They suck up the nutrients that we dump in the ocean, they release oxygen that we breathe,
they take up CO2 which is a greenhouse gas, all of the world's fisheries are supported by them, and
they're even very important for regulating climate.

What we've learned from these satellites is that nearly all of the variability that we see in the
phytoplankton can be related to changes in climate, and I'm sure many of you have used the
beautiful pictures from these satellites. What you might also know (maybe you don't) is that in
this week's issue of Science magazine on page 886 there's an article there calling attention to a
big problem. We're about to go colour-blind. We're about to lose our capability in the US to
continue measuring changes in our ocean ecosystems.

We have two new papers coming out this spring that summarise the results from ten years of ocean
colour measurements, and what we find is that in over 70% of the ocean, when the water warms the
phytoplankton go down. That's bad. When the water cools the phytoplankton vitality improves, and
that's good. It doesn't take a lot of imagination to figure out what happens if we continue to warm
the planet.

So what's happening in the other 25% of the ocean? The other 25% is the polar seas, and in the
Southern Ocean we're not yet seeing a very strong signal, so we don't know whether it's going up or
down. But in the northern seasonal seas we do have a strong signal. Interestingly, the trend there
is that when the waters warm the phytoplankton do better, which is the opposite of what we see in
the warm waters.

The second paper is going to appear in the Philosophical Translations of the Royal Society, and
what we've done in that paper is we've picked apart the satellite record even further, and what we
find is that for the first five years of the ten-year record nearly all the variability we see in
the phytoplankton is due to changes in their abundance, or their biomass. But the last five years
has been all physiology, it's all changes in the health of the cells. This is due to changes in the
amount of nutrients they get for growing and the amount of light that they actually see.

One point that's very important to make is that we only have ten years of data, which isn't very
long. Most of the variability we see is natural variability in the climate, it's El Nino, La Nina
variability. In order to detect the human signature we need more data, we need a longer time
series. SeaWiFS is a little satellite that's been our workhorse. In September of last year it
celebrated its 10th anniversary. On January 3rd this year it stopped sending data. MODIS-Aqua is
the last US satellite providing these data. The US has no plans of launching a satellite after
MODIS-Aqua that will pick up the baton. Doing satellite climate research is like doing a rely race;
one satellite hands the baton to the next which hands the baton to the next. We have no one with
arms picking up the baton after Aqua.

We're heading for strange days on planet Earth, and that's scary enough, but it looks like we're
heading without our eyes.