thoughts on a warm autumn day
Southwestern B.C. is recovering from flooding after torrential rainfall over the past few days, but now, here, on steeply sloping and therefore mostly floodproof North Vancouver, it is sunny and balmy, with great cumulus clouds tumbling slowly and silently over one another in a pristine blue sky. I'm just in from a short run, which I did in shorts. I could even have left my sweatshirt at home, it was so warm.
It all looks different, now that I'm reading The Revenge of Gaia by James Lovelock. Since it's a library book, I've been reading it here at the PC in the early morning over coffee, typing notes while I read. (It's not the most enjoyable way to read a book, but it is efficient if one is to take notes that are to make their way to the computer eventually.)
This morning I read chapter 3, "The Life History of Gaia", in which Lovelock sketches the history of Earth as a self-regulating system, which, he believes, it became shortly after the first life appeared on it over 3 billion years ago. Since then, Gaia has, like an organism, maintained itself in a state of dynamic equilibrium, with its constituent life-forms metabolizing and evolving in such a way that the overall environment is conducive to continued life. When there are perturbations to that equilibrium, Gaia has feedback mechanisms that push conditions back to life-optimal.
Lovelock says that textbooks are incorrect when they claim that Earth simply happens to be at a distance from the sun that makes it hospitable for life. There was a time, he says, about 2 billion years ago, when Gaia was in a "Goldilocks" period and no special mechanisms were required either to heat or cool the planet, but at the time life first appeared the sun was about 25% cooler than it is now. Since then it has grown steadily hotter, and will continue to do so until it finally explodes many billions of years from now.
He believes that Gaia has more than one equilibrium temperature. In this it is like the camel, which has two. By day, the camel maintains a body temperature of about 40 degrees Celsius, close to the ambient temperature of the desert air. But at night, the camel's temperature regulator is reset to about 34 degrees, so it can function without having to burn so much energy.
Depending on conditions in space and the life-forms on it, Gaia may have several of these equilibrium points. But Lovelock says that for the past several million years, as the sun has grown so hot, Gaia has shown a preference for ice ages, when the temperature was kept cooler, and the total amount of life may have been greater, due to the much larger land area around the tropics (exposed by dropped sea-level) and the much greater productivity of the cooler oceans (the great majority of open ocean is desert of life).
He believes that the long warming trend since the last ice age 12,000 years ago is a sign of Gaia's cooling mechanisms' being stretched beyond their capacity. Add to this our flaming-off of all the hydrocarbons stored beneath the surface of the Earth, creating a heating blanket around us, and we have the conditions for all-but-inevitable environmental catastrophe. Lovelock thinks it is probably already too late to stop this. We may be in the early stage of a sudden global heating such as has not been experienced since the onset of the Eocene epoch 55 million years ago, when temperatures shot up by 5 degrees Celsius in the tropics and 8 degrees elsewhere, turning Earth into a desert planet. The event was marked by mass extinctions.
The event can be sudden, in geological terms. Lovelock observes that all the heat-control mechanisms that we know of are in positive-feedback mode toward increasing temperature: shrinking ice-caps, shrinking forest cover, increasing greenhouse gases. The rate of heating will speed up until the next equilibrium point is reached (I'm assuming there is one--haven't finished the book!).
Will humanity survive? Sure. An adaptable species. But how many humans will that be? And will there be any memory of the world civilization we now take for granted? Or are we living in our own legend, like citizens in the last days of Atlantis?
It all looks different, now that I'm reading The Revenge of Gaia by James Lovelock. Since it's a library book, I've been reading it here at the PC in the early morning over coffee, typing notes while I read. (It's not the most enjoyable way to read a book, but it is efficient if one is to take notes that are to make their way to the computer eventually.)
This morning I read chapter 3, "The Life History of Gaia", in which Lovelock sketches the history of Earth as a self-regulating system, which, he believes, it became shortly after the first life appeared on it over 3 billion years ago. Since then, Gaia has, like an organism, maintained itself in a state of dynamic equilibrium, with its constituent life-forms metabolizing and evolving in such a way that the overall environment is conducive to continued life. When there are perturbations to that equilibrium, Gaia has feedback mechanisms that push conditions back to life-optimal.
Lovelock says that textbooks are incorrect when they claim that Earth simply happens to be at a distance from the sun that makes it hospitable for life. There was a time, he says, about 2 billion years ago, when Gaia was in a "Goldilocks" period and no special mechanisms were required either to heat or cool the planet, but at the time life first appeared the sun was about 25% cooler than it is now. Since then it has grown steadily hotter, and will continue to do so until it finally explodes many billions of years from now.
He believes that Gaia has more than one equilibrium temperature. In this it is like the camel, which has two. By day, the camel maintains a body temperature of about 40 degrees Celsius, close to the ambient temperature of the desert air. But at night, the camel's temperature regulator is reset to about 34 degrees, so it can function without having to burn so much energy.
Depending on conditions in space and the life-forms on it, Gaia may have several of these equilibrium points. But Lovelock says that for the past several million years, as the sun has grown so hot, Gaia has shown a preference for ice ages, when the temperature was kept cooler, and the total amount of life may have been greater, due to the much larger land area around the tropics (exposed by dropped sea-level) and the much greater productivity of the cooler oceans (the great majority of open ocean is desert of life).
He believes that the long warming trend since the last ice age 12,000 years ago is a sign of Gaia's cooling mechanisms' being stretched beyond their capacity. Add to this our flaming-off of all the hydrocarbons stored beneath the surface of the Earth, creating a heating blanket around us, and we have the conditions for all-but-inevitable environmental catastrophe. Lovelock thinks it is probably already too late to stop this. We may be in the early stage of a sudden global heating such as has not been experienced since the onset of the Eocene epoch 55 million years ago, when temperatures shot up by 5 degrees Celsius in the tropics and 8 degrees elsewhere, turning Earth into a desert planet. The event was marked by mass extinctions.
The event can be sudden, in geological terms. Lovelock observes that all the heat-control mechanisms that we know of are in positive-feedback mode toward increasing temperature: shrinking ice-caps, shrinking forest cover, increasing greenhouse gases. The rate of heating will speed up until the next equilibrium point is reached (I'm assuming there is one--haven't finished the book!).
Will humanity survive? Sure. An adaptable species. But how many humans will that be? And will there be any memory of the world civilization we now take for granted? Or are we living in our own legend, like citizens in the last days of Atlantis?
Labels: books by others, environment, local life
posted by paulv at
3:25 PM
0 Comments:
Post a Comment
<< Home