UCSB Study Chronicles Global Warming's Effect on Oceans

http://www.independent.com/news/2006/12/phytoplankton_from_outer_space.html

by Nick Welsh

[NOTE: First 2 1/2 paragraphs deleted by L Olsen]

Two weeks ago, Siegel and his team went public, publishing their

findings for the first time in the pages of the prestigious

scientific journal Nature. Given the report's significance in the

global warming debate, the group's findings have beenpicked up by

most mainstream media outlets and given extensive airplay on National

Public Radio.

Boiled down to its bare bones, the report concludes that there is

almost certainly a direct and powerful connection between water

temperature and phytoplankton health. From sea to sea, Siegel found

that as the ocean waters warmed, phytoplankton populations dropped

and seas turned bluer; when the waters cooled, phytoplankton

populations increased and seas turned greener.

Siegel said that in some ways he was not surprised by the results,

terming them "almost obvious." He noted, for example, that in Santa

Barbara, ocean water turns much greener and algae blooms under the

cooling influence of "June gloom." But what stunned and surprised

Siegel was the extent to which that same trend held true for all

14,000 data collection points located in every ocean across the

globe. "We could aggregate all the places of the ocean and show

numerically that there was a relationship between temperature and the

ocean's productivity," he said. "We saw that regularly and we saw

that glaringly." For example, he said, due to the influence of La

Nina during the first two years of the study -- 1996 and 1997 --

oceans were generally cooling off and

becoming greener. But from 1998 to 2004 -- the last year of data

collection -- oceans have generally increased in temperature and

blueness and decreased in productivity.

Siegel said he was surprised not just by the universality of the

relationship between temperature and productivity, but by the

strength of the relationship. Of the many mysterious factors that

could influence oceanic productivity, Siegel said temperature proved

unusually powerful. "I had my suspicions beforehand what the trend

would be," he said, "but I was astounded by how tight the coupling

was."

What makes Siegel's work so important in the global warming

discussion is not that he discovered the oceans were heating up at a

faster rate than anyone thought; he didn't. In fact, Siegel said,

some parts of the ocean are still cooling off. Rather, the real

importance of his findings lies in the universality of the

temperature/ productivity link, coupled with how vital phytoplankton

are to the web of life on planet Earth. "Obviously this is

speculative, but if we ratchet down on the fish food being naturally

produced, we might also be ratcheting down on the number of fish out

there to eat," Siegel said.

And phytoplankton are not only the essential unit in the oceanic food

chain, but also account for roughly one-half of the planet's

photosynthesis, the process by which plants convert sunlight into

energy. In that process, plants take in carbon dioxide and "exhale"

oxygen. If oceans absorb less carbon dioxide than they used to, then

presumably there will be more of it left in the atmosphere, which

could accelerate the pace of global warming. Experts estimate that

the planet's oceans have warmed by about one degree Fahrenheit in the

past 100 years. "What happens in 2050 when ocean temperatures might

increase by two degrees?" Siegel asked. "Plant life in the ocean will

certainly suffer." But if and when that happens, Siegel will have

provided future scientists a solid

baseline of reliable data from which to measure the decline.

Siegel is quick to stress that he was just one participant in a broad

multidisciplinary effort, working to increase the scientific

understanding --one brick at a time. But his peers at UCSB, like

paleoclimatologist Professor David Lee (who was uninvolved in the

project), credited Siegel for figuring out the mathematical

algorithms necessary to accurately translate the green picked up from

the space satellite --indicating phytoplankton's green chlorophyll --

into a reliable indicator of the plant's health and vitality.

These calculations involved placing a delicate optical instrument on

the tip of a spacecraft and sending it hurtling into space, then

sifting through a tidal wave of visual information, some of which had

been distorted by radiation, particulate matter in the atmosphere,

and even clouds. "Dave's been a real pioneer in developing the

methodology that lets the satellites detect these changes in color,"

said Lee. "It's a very good study. It doesn't mean that the ocean's

ecosystem is about to crash, but it's another way of recognizing and

quantifying how we're messing with something on a really grand scale."

The scientific reason why a warming trend means trouble for oceanic

plant life is that it restricts the mixing of shallow waters -- where

the phytoplankton live -- with the colder, deeper waters that contain

nutrients necessary for phytoplankton to thrive. The greater the

difference in temperature between the two layers, the less likely it

is that hotter surface waters will make the plunge down to where the

nutrients are, and vice versa. Simply put, global warming leads to a

more stratified ocean.

The oceanic effects of global warming have been recognized by some

scientists and businesses, which are seeking to remedy it by

artificially reconnecting the upper and lower strata -- thereby

jumpstarting the growth of phytoplankton. One company has proposed

doping the water with iron, one of the nutrients essential to

phytoplankton's survival. In exchange, it hopes to lay claim to the

increased carbon dioxide that would be absorbed into the ocean as a

result of the thriving phytoplankton. Such "carbon offsets" are now

the subject of intense speculative interest. But given that

phytoplankton have a life span of only two days, it's hard to know

how effective such a scheme would be’ or to predict its possible side

effects.

Siegel for one was skeptical. "I go to meetings and I hear people

saying these things," he said. "I know there's venture capital

involved in such things, but I'm tempted to check their reflexes to

make sure they're not stoned."

By Nick Welsh | December 20, 2006

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