THE Gaia hypothesis first proposed by British scientist James Lovelock – the notion that all living things are interlinked as a single self-regulating body – is popular with some scientists and accords with the idea that because human activity has changed the chemical composition of the atmosphere we are likely to be interfering with the climate and upsetting the balance of nature.
Paleontologist, Peter Ward, rejects the notion of Gaia, and is running a contrarian but equally hubris argument in his new book, ‘The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive?’ . Professor Ward suggests because there is no balance of nature mankind will needs to intervene and thus advocates geoengineering solutions including to climate change.
I suspect the comments in a recent review  are all together too kind, but nevertheless give some insights into The Medea:
“Looking at the evidence of past extinctions – written in fossils and in the chemical makeup of deeply buried rock sediments – as well as the workings of today’s oceans, atmosphere, and myriad food chains, he [Peter Ward] finds evidence of a planet that tends not toward harmony but toward extremes. Although windows of stability are possible, they are simply respites between catastrophic boom-and-bust cycles. He attributes one of the largest extinctions in history to the out-of-control proliferation of plankton feeding on upwellings of nutrients from the ocean floor. Rather than being elegantly brought back to equilibrium, the tiny organisms reproduced until they choked off much of the life in the upper ocean. Exhausting their newfound food supply, they died en masse, and decaying by the trillions used up all the oxygen in the water, killing off everything else.
As for the earth’s temperature control, Ward, drawing on the writing of the environmental scientist James Kirchner, points out that more often than not the thermostat seems to be hooked up backward, with warming triggering more warming, and cooling more cooling. In a process we’re seeing today, as the planetary temperature rises, warming increases the rate at which soil releases greenhouse gases – not only carbon dioxide, but methane and nitrous oxide. It leads to more forest growth in places that formerly were barren tundra, even as more carbon dioxide in the air makes plants hardier and better able to grow in areas once given over to desert. More plants in more places means a darker earth, and therefore a more heat-absorbent and warmer one. It’s an escalating feedback loop that becomes even more powerful as the planet’s white, ice-covered poles give way to darker open water.
The dangerous positive feedback can run the other way, too, Ward argues. He blames a planetary glut of plant life for the two prehistoric “snowball earth” episodes, 2.3 billion and 700 million years ago, when the planet froze from pole to pole. In a reverse greenhouse effect, the earth’s plants, photosynthesizing madly, sucked so much carbon dioxide out of the air that temperatures plunged. Far from nurturing life, the world’s plants nearly froze it to death.”
I agree with the evolutionary biologists, Richard Dawkins and Stephen Jay Gould, that the Gaia hypothesis, which some want elevated to a theory, is nonsense. Indeed anyone who subscribes to the general principles of Darwinian evolution must reject the concept of “self-regulating homeostasis” which is central to Gaia. In the same way a hypothesis, that suggests chaos without human intervention, underestimates the resilience of natural systems and also their ability to adapt and change including with extremes of climate.
Indeed both Professors Lovelock and Ward seem to have missed an essential feature of the natural world – change.
Peter Ward’s many books include the highly acclaimed Rare Earth: ‘Why Complex Life Is Uncommon in the Universe’ and ‘Under a Green Sky’ (Collins). He is professor of biology and Earth and space sciences at the University of Washington, and an astrobiologist with NASA.
 The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive? by Peter Ward, Princeton University Press http://press.princeton.edu/titles/8855.html
 Dark green: A scientist argues that the natural world isn’t benevolent and sustaining: it’s bent on self-destruction. By Drake Bennett, January 11, 2009 http://www.boston.com/bostonglobe/ideas/articles/2009/01/11/dark_green?mode=PF