For climate researcher Richard C.J. Somerville, a cloud does more than spoil a picnic. For geochemist Robin Keir, tiny one-celled plants floating in the sea are more than food for whales.
A small change in cloud cover can cool the Earth, a phenomenon that may account for the fact that the carbon-dioxide-induced global warming known as the greenhouse effect has not been as severe as otherwise would be expected, Somerville has found. And one-celled phytoplankton may have helped cool the climate during the last Ice Age by consuming carbon dioxide faster than volcanoes could release it, Keir suggests.
The two scientists at UC San Diego's Scripps Institution of Oceanography see both as parts of an emerging picture of how climate and life influence each other--and what that might mean for the planet's future.
Somerville and Keir described their research at a decidedly unconventional conference at the San Diego Princess hotel last week, the Chapman Conference on the Gaia Hypothesis.
Named after the Greek Earth goddess, Gaia is a controversial notion of Earth as a living organism whose parts work together--much as those in a human body do--to sustain life on the planet. It represents a radical departure from the traditional view of living things as passively reacting to their physical environment.
"The air, the oceans and the rocks are all either made by living organisms, or else changed by their presence," the father of Gaia, British scientist James Lovelock, has written. "Organisms do not just 'adapt' to a dead world determined by physics and chemistry alone. They live with a world that is the breath and bones of their ancestors and that they are now sustaining."
In such a framework, clouds that cool off the planet or microorganisms that consume carbon dioxide play a critical role.
Came Out With a Flourish
Although born in the shadow of the awakening environmental movement in the early 1970s, and nurtured since then mostly by a collection of what one scientist called "eco-freaks," Gaia came out of the closet with a flourish at last week's meeting.
There to greet her were an international collection of noted atmospheric, earth and biological scientists who, for the first time, met to debate the merits of an idea that many of them have derided for years.
That the meeting was held by the stodgy American Geophysical Union at all was a source of embarrassment for and criticism from some scientists who declined to attend.
"Gaia has no scientific basis . . . It has no business being the subject of a Chapman conference," wrote Wallace Broecker, of Columbia University's Lamont-Doherty Geological Observatory in a letter to a conference organizer, Stephen H. Schneider.
Schneider is head of climate systems research at the National Center for Atmospheric Research in Boulder, Colo.
Attracted 162 Scientists
But Schneider was unruffled--especially since the meeting did attract 162 scientists, including some of the leaders in geophysical research.
"These are people like Dick Holland.
These are members of the National Academy of Sciences. These are not flakes," Schneider said. "And they're coming because they, too, think Gaia should come out of the fringes."
Holland, a geochemist at Harvard University, laughingly acknowledged his role as one of the hard-core Gaia detractors at the meeting, but said he still found it useful.
"It brought together a lot of people, a lot of different disciplines, who asked the question, 'What is the role of the biosphere in the operation of the atmosphere and the oceans?' " Holland said.
Stanford University population biologist Paul R. Ehrlich, who discounted Gaia in a keynote address, said Lovelock has nevertheless made a significant contribution with his ideas.
"I think what will come out of it is that the hypothesis has been very important in a poetic sense, of calling attention to the importance of organisms to the entire global environment," Ehrlich said.
Indeed, it was that underlying concept of the Earth as one unified system that apparently drew so many noted researchers together to debate--sometimes contentiously--specific aspects of the Gaia hypothesis:
If the Earth is a living organism, what are its boundaries? How does one solve the chicken-egg proposition of whether an organism's evolutionary adaptation caused a change in the environment or resulted from it? If different forms of life are cooperating to keep Gaia healthy, will one life form "sacrifice" itself for the good of another--as when ancient oxygen-hating bacteria produced so much oxygen that they could no longer live in most of the world? (This same oxygen made life as we know it possible.)
But consistently the scientists asked: Is the Gaia idea more of an intuitive metaphysical concept than a scientific hypothesis that can be tested?