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Wednesday, May 20, 2009

Earth Perhaps Not Such a Benevolent Mother After All

Most of us think of Earth as a nurturing place, with a natural equilibrium where life thrives and flourishes.

Some refer to that idea as the Gaia hypothesis, named for the ancient Greek goddess of Earth. The Gaia hypothesis suggests that the planet behaves as a kind of giant organism, with its complex systems finely tuned to compensate when one system gets out of kilter.

But Peter Ward, a University of Washington paleontologist, says that it is the Gaia view that is out of kilter. Ward has looked closely at conditions that existed during numerous mass extinction events in Earth's history to draw the conclusion that the Earth maybe isn't such a hospitable, harmonious nurturing mother after all.

In a new book, he suggests the planet ultimately is inhospitable to life, and that life itself might be the primary reason. Rather than Gaia, he invokes the darker Medea from Greek mythology.

"The Medea hypothesis says life is already shutting down Earth as a habitable planet. Not just the diversity of life, but the actual biomass," Ward said. "Life keeps evolving, and there are unintended, often negative, consequences."

"The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive?" was published in April by Princeton University Press. In the 208-page book, Ward argues that humans have to use engineering to manage their environment or face potential extinction if the Earth is left to manage itself.

"The engineering I'm talking about is not girders and sky shields. It's engineering microbes to take over food production and energy production," he said.

Microbes have undergone evolution, a sort of natural engineering, throughout Earth's history, he said, and humans have the ability to guide such changes to clean the environment, for example, or regulate carbon dioxide in the atmosphere.

Like Gaia, Medea is a mythological character, though she is decidedly much darker in nature. Medea was married to Jason at the time he pursued the Golden Fleece but, according to legend, he left her and in revenge she killed their two children.

Ward, a UW professor of biology and of Earth and space sciences, says numerous mass extinctions show that our planet behaves in somewhat the same way. For example:

**The evolution of oxygen-producing organisms twice plunged Earth into ice ages as carbon dioxide, crucial for photosynthesis, was stripped from the atmosphere.

**The evolution of the first true animals caused extinction of most stromatolites, layers of microbes living in sediment in the oceans' intertidal zones. The result was somewhat more complex life forms, but a vastly smaller volume of living matter.

**The evolution of the first forests 400 million years ago is considered one of the great events in Earth history. But tree roots pushed into subsurface rocks, exposing them to increased weathering. The weathered elements again stripped carbon dioxide from the atmosphere and plunged the Earth into a 90 million-year ice age.

"The irony is that we have way too much carbon dioxide right now, but we should stash it in a bank because we're going to need it," Ward said. "The end of life as we know it is when we reach just 10 parts per million of carbon dioxide in the atmosphere."

Currently, carbon dioxide is at 380 parts per million and rising, creating a greenhouse effect that most climate scientists say will greatly increase temperatures around the world, with some severe consequences. For example, with the melting of mountain and polar ice sheets, the world's most-productive agricultural land will be submerged and humans will struggle to find food, Ward said.

He noted that throughout Earth's history, carbon has been stripped from the atmosphere and stored in trees, rocks, even the oceans. He said those processes will continue until atmospheric carbon dioxide drops to 10 parts per million, a point at which no plants can live. Once plants are gone, within 20 million years the oxygen will plummet to 1 percent of the total atmosphere and life as we know it will end.

"Then you've gotten to a point where it will be forever impossible to get diversity of life back. It will be forever impossible to regain an oxygen-rich atmosphere. That's not Gaia. It's the opposite of Gaia," he said.

He notes that of 15 mass extinction events in Earth's history, only the one 65 million years ago that brought an end to the age of dinosaurs was likely caused by a comet or asteroid crashing into the planet's surface. The others all resulted from Earth's own processes.

"There's no Gaia. There's just this dumb, blind life. It tries out all kinds of new things that are good for new kinds of life but are detrimental to everything else that exists. The innovations lead to disaster," Ward said.

He added that, contrary to recently popular beliefs, the planet likely would not somehow "heal itself" if all humans were suddenly removed. Instead, he said, humans are the key to saving the planet and, in the end, are perhaps the only true Gaian force.

"We're not renting. We're the owners, but there can be a cost to the rest of nature of our ownership," Ward said. "There is an easy fix – the only fix is intelligence. Knowing that there is a problem is what will get us out of it. We're the only ones who can put our hands on the controls."

7 comments:

  1. I do agree with the fact that extinction level events have occurred in Earth. I´ve just read the Newswise report: "...On the need to develop an international decision-making program to respond to the threat of Near Earth Objects (NEOs) has been briefed to United Nations officials in Vienna, Austria". Why don’t governments start a huge worldwide project to preserve humankind? This may sound insane for many people but it is more insane to keep on waiting until an asteroid causes our extinction. The worst scenario is a massive asteroid hitting our planet causing enormous tsunamis to wipe out entire cities, dust would block the atmosphere, preventing the earth from getting any sun. Plant life would become extinct, and a nuclear winter would begin .Maybe a deadly impact is unlikely to happen soon but we cannot put at risk our existence in the hope that a megadisaster will never happen. This is no joke. We have to build underground cities (nuclear powered - artificial light to keep plants growing to provide food and oxygen, etc.). A HUMAN PRESERVATION PROJECT must be initiated.

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  2. I agree with what you said. We as humans may be the only things keeping the Earth alive. but don't you think that we are also using much of its resources? We may be keeping it alive, but we may be taking in order to give, almost like a double edged sword. We are sustaining life, but we are also killing off life forms as we do it. Above that, many people are unaware of the state that the earth is in, or is just being ignorant. So we just may be doomed. (Hopefully the citizens of Earth will come up with a way to save us with intelligence, or my generation will come up with something)

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  3. i agree to but will the "big PeoPLE" who's sitting on the the power and the cash ever get the message that we are destroying ourselves i believe not so..... what do we do ?

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