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1. What's happening to global climate?

Gaia's Fever

- B Y JOSE LUTZENBERGER -

The range of temperatures within which life can exist and flourish - that is, the range of temperatures that makes biochemistry possible, the chem­ istry of proteins, carbohydrates, hydrocarbons, nucleic acids, the building of living cells and organisms, which is also the range in which water can coexist in its three physical forms, liquid, gaseous and solid - is extremely narrow when compared with the temperatures that prevail in the universe at large.

Or, i f for some reason, at the time of the first stirrings of life, with the cooler Sun, there had been too much cloudiness, the runaway could have gone in the other direction. The higher albedo - that is, the higher reflectivity for light - would have sent much of the incident solar energy back into empty space. Less heat, more snow, still more albedo, still less heat. The Earth could have become an ice-covered ball. Either way, Gaia would not have come into existence or would soon have perished.

The temperatures range from close to absolute zero, 273 degrees Centigrade below zero in interstellar and interplanetary space or on our far out planets such as Neptune and Pluto, to between 400 and 500 degrees Centigrade on Venus, close to 40 degrees below zero in summer at noon on the equator on Mars, about 6,000 degrees on the sur­ face of our sun, close to 20 mil­ lion degrees in its interior, much, much hotter in bigger stars and up to hundreds of billions of degrees Centigrade in the fur­ naces of imploding stars, the supernovas. I f we were to repre­ sent this existing range of tem­ peratures on a line where every degree is one millimetre, the line would be several hundreds of thousands of kilometres long. It would reach far beyond the Moon. The range propitious to life ranges from a few degrees below zero, where life survives by resting, to about 80 degrees above zero for a few organisms, some bacteria and algae that man­ age to live in hot springs, which makes a total of about 100 degrees. When plotted against that line it would cover ten cen­ timetres. Ten centimetres on several hundred thousand kilometres!

We know we are messing up all the mechanisms of climate control, with too much carbon dioxide, methane, nitrous

oxide, freons, forest destruction and desertification. How long can we abuse

the system? How long will it take for

Gaia to catch a fever?

And yet, we know we are messing up all the mechanisms of climate control, with too much carbon dioxide, methane, nitro­ gen oxide, sulphur oxide, freons, hydrocarbons, forest destruction and desertification. How long can we abuse the system? How long will it take for Gaia to catch a fever? Do we really have to know all the details in order to act?

I f things go wrong now, they don't even have to go wrong all the way. We don't have to have another ice age or a melting of the ice caps on Greenland and the Antarctic, with flooding of major cities and highly populated terri­ tories. An exacerbation of the cli­ matic irregularities we already have will soon leave us in a situa­ tion where we cannot count on safe harvests any more. We are now nearly six billion people. Food reserves are getting shorter.

What good would nice beach weather be on Spitzbergen i f we had nothing to eat? And what about the social calamities and upheavals that would result, with figures like Saddam Hussein and others having access to weapons of mass destruction?

As seen from this perspective, we realize how precious is our world. It is even more precious when we learn that life, for over three and a half billion years, has been able to counteract forces tending to make the Earth much hotter or much colder. We know from cosmological considerations that the Sun is today between 20 and 30 per cent hotter than it was when life began to structure itself in the primeval oceans. Our planet could have ended up in a situation of a runaway greenhouse effect, like Venus: a little cool­ er, but still around two hundred degrees above zero. The oceans would have evaporated.

What for Gaia in the lifespan of ten billion years, with at least another five billion to go, may be a soft and momentary fever, could be the end of civilisation for us.

A wise person may risk learning from mistakes, but will avoid experiments where, i f things go wrong, the consequences are unacceptable and irreversible. How can we make the powerful understand that Modern Industrial Society is engaged in just this kind of experiment?

Jose Lutzenberger is the former Brazilian Minister for the Environment. He is now President of Fundacio Gaia in Brazil.

The Ecologist, Vol. 29, No 2, March/April 1999

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