Nature Outlook _talks to Rutgers University environmental scientist Paul Falkowski about the effects of human activity and climate change on communities of life-sustaining oceanic

microorganisms_. HOW DID YOU FIRST RECOGNIZE THE IMPORTANCE OF PHYTOPLANKTON TO OCEANIC HEALTH? Credit: NICK HIGGINS When I was at the Brookhaven National Laboratory, I was involved in

developing algorithms enabling satellites to estimate photosynthetic productivity — the amount of organic matter that phytoplankton incorporate into their bodies through photosynthesis —

from space. I started to put together maps that were really surprising. Half the productivity in the world was being done by organisms that account for less than 1% of the photosynthetic

produce huge numbers of seeds like trees or grasses. These organisms have a very simple, but very successful, life strategy. BEYOND THE IMPACT OF INDUSTRIALIZATION ON RISING OCEANIC

TEMPERATURES AND THE RESULTING REDUCTION IN PHYTOPLANKTON GROWTH, HOW ELSE ARE HUMAN ACTIVITIES AFFECTING PHYTOPLANKTON POPULATIONS? One of the other big problems is eutrophication of the

coastal oceans, that is, the addition of huge amounts of nutrients to the water. You can see this resulting in massive phytoplankton blooms, which trigger processes that deplete the water of

oxygen. The one most familiar to Americans would be the so-called 'dead zone' in the Gulf of Mexico. These blooms can be phenomenally large, tens of thousands of square

kilometres. ARE THERE ANY EXAMPLES OF SUCH SITES BEING SUCCESSFULLY RESTORED? The most successful case in the United States is probably the Hudson River. New York City finally established

tertiary treatment plants for sewage, and far fewer nutrients flow out of the Hudson River into the mid-Atlantic than was the case 20 or 30 years ago. But these are expensive solutions, and

many communities don't want to pay for these kinds of treatments. As a whole, we're going the other way. The Chesapeake Bay on the US east coast, for example, receives massive

amounts of nutrients from chicken farms. It's very difficult to reduce these nutrient flows because they're so widely distributed. The Mississippi River is particular tough to deal

with because it carries run-offs from farms throughout the entire Mississippi drainage basin, which is enormous. DOES THE CLIMATE SCIENCE COMMUNITY AS A WHOLE RECOGNIZE THE IMPORTANCE OF

OCEANIC LIFE AS A FACTOR? Most people working on climate are physicists, who don't generally think much about biological processes, and who tend to think that ocean productivity is

irrelevant. On short time scales of a decade or so that's true, but on longer time scales that's not true. What's going to happen, though, is that the changes in the climate

over the next 100 or 200 years will alter the productivity of the planet, and I'm afraid it's not going to be for the better. ARE YOU SEEING MORE OPPORTUNITIES FOR

INTERDISCIPLINARY COMMUNICATION AND COLLABORATION IN THE CLIMATE FIELD? There is a nascent field that we call 'Earth systems science', which attempts to integrate biological

effects with the physical processes of the planet. But progress in this area has been slow because the physics of the planet is still not completely understood. Physicists spend an awful lot

of time designing complex climate-change models, and to some extent they incorporate feedbacks from biological systems, but they focus mainly on terrestrial ecosystems. There is a failure

to integrate this vitally important component of the Earth into climate feedbacks. FOR AREAS OF THE OCEAN THAT ARE LOSING PHYTOPLANKTON, WHAT SORT OF IMPACTS CAN WE ANTICIPATE? We're

looking at a slow, long-term decline in photosynthetic productivity — we're already seeing this in satellite images of the open Atlantic and Pacific oceans. What this means for humans

is that large open-sea fisheries, such as those for tuna, will be hard hit in the coming years. GIVEN THEIR RAPID TURNOVER RATE, MIGHT PHYTOPLANKTON ADAPT IN WAYS THAT COULD DELAY THIS

DECLINE? No, they can't adapt on this timescale. There have been five major extinction events that naturally occurred and that we can see in the geological record. We are going through

a sixth extinction event, and this one is entirely due to humans. HOW SEVERE DO YOU BELIEVE THE ENVIRONMENTAL DAMAGE IS? I think that in the best case, it would take a long time — probably

about 1,000 years — for the current damage to be reversed. The phytoplankton will survive, but humans are going to pay the price. I find it very discouraging that a large segment of US

society is not accepting conclusions that are based on objective science. It's distressing because everybody seems to be their own climate expert. I don't think humans realize that

we're a vulnerable species. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Paul Falkowski is the Bennett L. Smith Professor in the Institute of Marine and Coastal Sciences and the

Department of Earth and Planetary Sciences at Rutgers University., Paul Falkowski Authors * Paul Falkowski View author publications You can also search for this author inPubMed Google

Scholar ADDITIONAL INFORMATION Interview by MICHAEL EISENSTEIN, a freelance writer based in Philadelphia Pennsylvania. RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE

THIS ARTICLE Falkowski, P. Q&A: A slow-motion crisis. _Nature_ 483, S21 (2012). https://doi.org/10.1038/483S21a Download citation * Published: 29 February 2012 * Issue Date: 01 March

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