In his latest ruminations on Gaia, the 90-year-old Lovelock abandons almost all hope. He contends Earth is overpopulated, overworked and beyond recovery. Climate change and its effects, he writes, will radically and inevitably make the planet hotter, drier and deadlier.
If humanity is to survive, Lovelock says, society must now act swiftly and decisively, junking current half-measures and incremental approaches in favor of things like massive nuclear energy programs and aggressive agricultural development of dwindling arable lands.
Even then, predicts Lovelock, only the fittest – and fewest – will survive.
In Greek mythology, the goddess Gaia emerges from Chaos to, among other things, give rise to all creatures of Earth. She is Mother Nature: powerful and omnipresent, but nurturing, too, the protector and sustainer of life.
In the 1960s, James Lovelock, a widely respected English atmospheric scientist, began thinking Earth behaved a lot like Gaia, its various biological components and physical systems interacting to maintain optimum conditions for life. Lovelock eventually imagined the planet as a kind of nurturing, self-regulating superorganism.
“The entire range of living matter,” he wrote in 1979, everything from viruses to oaks to whales, “could be regarded as constituting a single living entity capable of maintaining the Earth's atmosphere to suit its overall needs and endowed with faculties and powers far beyond those of its constituent parts.”
At the suggestion of his neighbor, William Golding, the author of “The Lord of the Flies,” Lovelock dubbed this idea the Gaia hypothesis. And while it was initially scorned, Lovelock's hypothesis has not only endured, but thrived. Environmentalists now embrace its compelling imagery of a living, breathing planet. It inspired a new field of Earth systems science. Lovelock and others expanded and refined the concept, steadily gathering evidence they said showed life actively controlling – or at least strongly influencing – physical phenomena like temperature, atmospheric chemistry and ocean salinity.
Among adherents, Gaia transcended mere hypothesis. It became scientific theory, not unlike gravity or evolution.
But not all scientists have become true believers. Some balk and chafe at the notion of Gaia. Among them is Peter Ward, a paleontologist at the University of Washington and NASA astrobiologist who says “the whole idea is nonsensical.”
“Lovelock is a great scientist, absolutely brilliant, but parts of this hypothesis are just New Age, feel-good mumbo jumbo. It's a crutch, this notion that life will always find a way.”
In a new book, Ward argues that the nature of life on Earth is distinctively non-Gaian. Instead, life behaves more like another figure from Greek mythology – Medea, the granddaughter of the sun god Helios, wife to Jason of the Argonauts, killer of her own children.
In “The Medea Hypothesis” (Princeton University Press), Ward asserts that life may be its own worst enemy. Rather than working to sustain and promote itself, life regularly takes itself out, creating conditions that have resulted in some of the planet's worst mass extinctions.
“Unfortunately, this idea that if we could just get back to nature everything would be fine is not true,” said Ward. “Life has a history of doing bad things to itself.”
Ward's argument originates with the earliest days of life 3.7 billion years ago, a time when, he says, extensive microbial blooms saturated the planet's atmosphere with methane gas, creating a worldwide blanket of smog that blotted the sun and nearly eradicated incipient life.
But worse, said Ward, was a subsequent mass extinction 2.3 billion years ago when the Earth endured a period of global glaciation lasting 100 million years. The cause, says Ward, was again life itself.
Two hundred million years earlier, photosynthesis had debuted, the biological process by which atmospheric carbon dioxide and sunlight are converted into usable energy, with oxygen generated as a waste product.
Before photosynthesis, atmospheric levels of oxygen were relatively low. The gas was poisonous to early life. But with the emergence of photosynthesis, microbes began sucking so much heat-trapping carbon dioxide out of the atmosphere that the planet froze, said Ward. Virtually everything died, except for the photosynthesizers and microbes that quickly adapted to tolerate higher oxygen levels.
Ward says the rise of multicellular plants produced a similar cataclysmic decline in atmospheric CO2 and a second “snowball Earth” 700 million years ago. And he contends there is strong evidence most of the mass extinctions since the evolution of animals 565 million years ago have been, in some way, driven by adverse microbial activity.
These biologically induced mass extinctions are quite contrary to the idyllic concepts of Gaia, says Ward. And while life on Earth has enjoyed long periods of stability, Ward adds that it also has a nasty streak of self-destructiveness that is bound to rise again. Next time, he said, will be the last time.
The end begins with the sun, according to Ward, which has increased in brightness by about 30 percent over the past 4.5 billion years. That trend will continue, spurring global warming which will, in turn, boost the weathering rate of silicate rocks like granite, a process that chemically removes CO2 from the atmosphere.
At first, Ward speculates, the atmospheric loss of CO2 will benefit life by buffering the rising temperatures caused by a hotter sun. But at some point – perhaps 500 million years from now – there will not be enough CO2 left in the atmosphere to support photosynthesis. Plants will die; animals will follow. The loss of photosynthetic life will lead to a renewed buildup of carbon dioxide in the atmosphere, a runaway greenhouse effect and, in time, a planet too hot to sustain even microbial life. The Earth will return to its original state: a barren, sterile rock in space.
Like Lovelock's Gaia, Ward's Medea hypothesis has skeptics and critics.
Lynn Margulis, a noted biologist at the University of Massachusetts, Amherst, who helped Lovelock shape and promote the Gaia concept, dismisses Ward's work as misguided, describing it as “pseudo-quantitation, a nice example of the fallacy of misplaced concreteness.”
J. David Archibald, a professor of biology and a vertebrate paleontologist at San Diego State University, said he was “underwhelmed” by the Medea idea. “I don't know that it tells us anything we didn't already know.”
Christopher Wills, a biologist at the University of California San Diego and co-author of “The Spark of Life,” a 2001 book on the origins of life on Earth, said it was too simplistic to say life causes mass extinctions. There are other, perhaps more compelling, factors, too.
“The dramatic changes in the Earth's climate have been accompanied by meteorite impacts and truly mind-boggling massive volcanic eruptions,” said Wills. “The Siberian eruptions that accompanied the great Permo-Triassic extinction 200 million years ago piled up layers of lava 10,000 feet thick over an area of 75,000 square miles. Life didn't cause that.”
Wills' co-author, Jeffrey Bada, a marine chemist at the Scripps Institution of Oceanography, also found the hypothesis wanting, particularly its eventual doomsday scenario.
“Given the ability for life on Earth to seemingly adopt to slowly changing conditions, I find the hypothesis to be far-fetched. There are certainly bacteria, some of which are photosynthetic, that would survive (increased solar radiation). And there is convincing evidence that some bacteria live far below the surface of the Earth, so they would be survivors as well.
“Animals, including humans, would probably have a rough go, but given the billion-year time scale for this scenario, it is likely that other catastrophes – a large impact event, nuclear war – would do these life-forms in before the heating was severe.”
Ward also expects humanity to suffer in the shorter term, largely from problems of its own making. “There are too many people on the planet. We're consuming resources too rapidly. We're exacerbating climate change. In the short term, we will have some horrible things to deal with.”
Nonetheless, Ward considers his hypothesis to be the more optimistic of the two. “Lovelock's point of view is that humans are house-wreckers. My point of view is that we're house-savers. His point is that if you get rid of humans, things would be good. I say our job is to keep the whole damn thing together.
“Gaia makes people sound like a global infection, like we're microbes. The fact is, we've been here awhile. We've co-evolved with other species. We're part of the Earth. The difference between us and other species is that we're technological, intelligent.”
Ward said there's “no going back to nature.”
“Nobody wants to return to sitting around campfires with no clothes. The challenge is finding the least amount of technology that we, as a species, are willing to live with that's harmonious with keeping alive as many other species as possible.”
Ward believes – or at least strongly hopes – that human society will somehow muddle through the next few centuries, that it will find ways to minimize and adapt to predicted or unexpected environmental catastrophes like climate change, rising sea levels and mass extinction.
“If we get over this hump, if we get the next 500 years out of the way, then I'm hoping technology will allow us to move forward on the planet we have left.”
The Gaia concept has been much modified over the decades, both by its inventor James Lovelock and by others. There are multiple variants, from early interpretations that proposed life actively controlled its physical environment to more recent, finely tuned suggestions that life creates feedback loops that keep some life-constraining factors, such as temperature and atmospheric gas levels, within certain acceptable ranges.
This latter idea of a “homeostatic” or balanced world is most vividly illustrated in Lovelock's theoretical example of “Daisyworld,” says Christopher Wills, a professor of biology at the University of California San Diego.
“Imagine a planet covered with dark and light daisies. If there are lots of dark daisies, the temperature increases. But dark daisies heat up and suffer. Light daisies have an advantage because they reflect the heat and stay cooler. They begin to multiply, increasing the reflectivity of the planet. But now, as it cools down, light daisies reflect the heat and don't keep warm while dark daisies stay cozy.
“Daisyworld stays within narrow temperature limits because of a process biologists call frequency-dependence, in which an organism such as dark daisies is at an advantage when it is rare and at a disadvantage when it is common. Lovelock's modified idea for how Gaia might operate has found some favor among biologists, who see frequency-dependence in many complex systems. My colleagues and I, for example, found frequency-dependence operating to maintain diversity in tropical rain forests. But whether frequency-dependence is operating planetwide remains to be demonstrated.”Copyright © 2017, The San Diego Union-Tribune