Science in Society Archive

I-SIS Special Miniseries - Life of Gaia

This miniseries is dedicated to our planet earth, so we may better appreciate how she lives and sustains all creatures large and small, that we may learn to dance to the complex rhythms of her life music without stopping her in her tracks.

Space scientist and inventor Jim Lovelock first proposed in the 1970s that the entire earth is a self-organizing, self-regulating entity, rather like an organism. He named the earth Gaia, after the Greek earth goddess.

The idea that Gaia is alive and has a life of her own immediately caught fire. It inspired many earth scientists to look for the dynamic processes that organize and regulate the currents of the earth, to make a congenial home for all her inhabitants. These scientists are richly rewarded.

Records from ice and deep sea cores show detailed globally correlated changes going back at least 800 000 years, leaving us in no doubt that the earth behaves from moment to moment as one coherent whole, just like an organism.

Not only can we can read Gaia’s life-history from her deep memory stores, we can also tune in to her life-force pulsing as she is living today.

Gaia spinning in her perpetual dance around the sun, her mighty breath tumbling from hot belly to the poles, swirling across the continents, bringing welcome rain to forests, grasslands and crops, or torrential downpours, floods and hurricanes. Vast slow vortices of water connect her oceans from the furthest northern reaches to the southernmost haunts, from the shimmering sea surfaces to the dark deep beds, distributing warmth and nutrients, sustaining life with life.

Gaia’s breath is our breath, her water our water. Let Gaia live that we may live.

Why the United States Needs the Amazon

The ‘Tele’connection

The US cornbelt will shrivel if the Amazon is destroyed. Peter Bunyard reports.

During the ‘Dust Bowl’ years of the 1930s, yields of wheat and maize plummeted by 50 per cent as the soil just blew away in monstrous swirling clouds, engulfing everything in their path. Hindsight tells us that much of the horrors of those years resulted from putting the plough to wind-swept, vulnerable soils that had never before been tilled. No hint of conservation practices then, not like today. But just imagine how corn-belt farmers now would react to being told that in the foreseeable future, a generation away at best, their sons and daughters would be seeing their crops shrivel and die in the baking sun, the precious soil once again blown away? And, we are not talking of a year once every so often, but year after year in devastating succession, turning what was the granary of the United States into desert.

So how come, given the difficulty we have of forecasting weather a few days’ hence, let alone days, months, or even years away, that we can come up with such dire predictions? It all comes down to what is happening thousands of miles down to the south, in the Amazon, to the way that the forest, covering nearly two million square miles, pumps water that has fallen as rain back into the atmosphere (see "Why Gaia needs rainforests", this series).

As Brazilian physicists have shown, more than half the rain that falls over the Amazon either gets evaporated from the tree trunks before it ever trickles to the ground or gets pumped out as vapour through the millions upon millions of pores found in every leaf. This combined process of evapo-transpiration puts back into the atmosphere more than 6 million million tonnes of water vapour every year - equivalent to staggering amounts of energy as the vapour condenses into rain. And it is that energy - captured as masses of humid air – which brings heat and rain to more temperate parts of the planet, and especially the Americas. Argentina gets no less than half of its rain, courtesy of the Amazon. The United States, too receives its share of the bounty.

Through an extraordinary process, recently unravelled by climatologists in the United States, Brazil and Britain, we now know that what falls as rain over the Amazon Basin is paralleled, three to four months later, in rain falling over the US corn belt during its spring and summer. ‘Teleconnection’ is the name given to the process that transfers energy and rain to the United States from Amazonia. Relatively slow-moving moist masses of air, taking some months to complete their journey, seek conduits in the atmospheric circulation system, pushing their way through mass-circulation systems such as the Hadley Cell and the high flying Easterlies. These waves of Amazonian air, fuelled by the water vapour they carry, then release their rain en route over the corn-belt regions of the US.

We are talking of the rains that are essential for the growth and survival of crops fundamental to the needs of the United States, let alone the rest of the world. Let the forest wither away, or just cut it and burn it down, and the US as well as the world will suffer like no-one had ever imagined they would.

The current US administration may have forgotten that in the drought of 1988, caused by a powerful El Niňo (see later), the United States had a foretaste of what is to come. Corn yields fell by more than a quarter, swallowing up the surpluses of previous years, and for the first time leaving production behind US consumption. The federal government was forced to pay out three billion dollars just in direct relief to farmers.

The irony is that much of the recent deforestation in the Brazilian Amazon, particularly in the States of Mato Grosso and Para, is for growing soya beans to meet the European demand for non-genetically modified produce, and in addition, to feed China’s ever growing demands for soya-fed poultry and pigs. What we now see, all too typically at Santarem in the State of Para, is none other than thousands upon thousands of acres of monoculture soya, stretching from horizon to horizon. The species-rich tropical forest has gone forever (see "Soya destroying Amazon", this series).

Climatologists at the UK Met Office’s Hadley Centre have already discovered that, as the world warms up, the air currents bringing rain to the Amazon can suddenly switch El Niňo-like to a climate regime that is much drier and warmer. In El Niňo years, the southern Pacific Ocean currents reverse the normal east to west direction, with major impacts on climate across the globe. Indonesia and Australia, instead of enjoying the low-pressure system that brings tropical rains, find themselves burning in heat waves and having to endure drought-conditions. On the other side of the Pacific, countries such as Peru find themselves suffering torrential rain and warm coastal waters that keep the nutrient-rich cold waters of the Humboldt Current at bay, with plummeting fish-catches. During El Niňo years, the Amazon tends to dry out as the rain-bearing air masses of the east to west circulation across the equatorial belt are weakened and deflected. Moreover, it is likely to prove highly destructive to the forest, through causing it to dry out, die-back and become extremely vulnerable to fires.

As the forest withers back, its mass of carbon, some 200 tonnes for each hectare, is decomposed into carbon dioxide and methane, so building up still more the greenhouse gases in the atmosphere. With the forest virtually all gone, more than 70 billion tonnes of carbon gases will find their way into the atmosphere. From their projections of the consequences of greenhouse gas build-up, Peter Cox and his colleague Richard Betts at the Hadley Centre are projecting average global terrestrial temperatures to go up by nearly 9 C before the end of this century from the pre-industrial levels of 150 years ago. That level of warming was last evidenced more than 40 million years ago, when neither of the Poles had permanent ice (see "Back to the future for Gaia", this series) Sea levels were then more than a hundred metre higher than today. At current greenhouse gas emission rates we have a few decades at best before the forest begins its inexorable process of die-back and decomposition.

The current frenzied destruction of the rainforest is very likely to hasten the total collapse of the Amazon. Thunderstorms are the key to the survival of the forest because they bring essential rain, in some parts of the Amazon, as in Colombia, to the tune of 40 feet a year. Cut the forest down and rainfall dwindles. That causes still more of the forest to die, so reducing rainfall still further and bringing about a vicious cycle of spreading degradation as fires begin to rage out of control. Recent research indicates that more thunderstorms then brew because of the soot and ash in the air. The result is more fire-inducing lightning strikes.

Climatologist Roni Avissar has discovered that the loss of rainfall is not a smooth process related directly to the loss of forest. On the contrary, interspersed clearings between large areas of forest cause rainfall over that region to increase by as much as 30 per cent. The reason is that the clearing heats up during the day, considerably more than the forest, which cools itself through processes of evapo-transpiration. A mass of air then rises over the clearing, being replaced by cooler more humid air that is drawn in from the surrounding forest. As the now-moistened air rises it convects into massive cumulo-nimbus thunderstorm clouds that then cause powerful downpours to drench the land around. On that basis, modest-size clearings are not a disaster. The forest can cope. On the other hand, make the clearing too big, say more than 100 kilometres across, and the forest can sustain its humidity no longer. Literally, the convection process runs out steam and the number of rain-bearing thunderstorms drops dramatically. This is yet another example of the non-linear, threshold effects that can precipitate abrupt change.

We are now perilously close to the critical point in certain areas of the Amazon, such as in Para, Rondonia and the Mato Grosso, when any further loss of forest will lead to a dramatic decline in rainfall. And that, says Avissar, will have a direct and dire impact on the United States. His models show rainfall declining by as much as 15 to 20 per cent over agricultural regions in the United States during the critical growing months - shades of the Dust Bowl era all over again - once the Amazon collapses as a rainforest system.

Whether it likes it or not, the United States is threatened on both counts. First, because within decades from now the Amazon is likely to self-destruct through being sucked dry by agro-industry. Second, the accumulating impact of greenhouse gases in the atmosphere, is likely to lead within the same time-span, to a sudden switch in air mass movements over the Pacific and the Americas. Those El Niňo -like changes will also cause a drying-out, accentuating the impact of those same agro-industrial clearings.

We don’t have to let it happen. To date, the United States has acted with supreme selfishness in failing to ratify the Kyoto Protocol and so reduce its excessive greenhouse gas emissions. It now needs to act with equal selfishness in signing up to such Protocols; its own future is at stake. That applies to all of us, in Europe, Asia, the Americas. We have a decade at best to get our emissions in order. But, in no less measure we must all act to ensure that the greater part of the Amazon is conserved. The reasons are primarily for safeguarding our climate. In so doing we would naturally conserve its extraordinary biodiversity - a diversity of forms that holds the fabric of the forest together and is the key to a safer world.

Article first published 07/10/03


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  2. Pielke RA. Mesoscale meteorological modeling, 2nd edition. San Diego: Academic Press, 2002.
  3. Salati E. The Forest and the Hydrological Cycle. In The Geophysiology of Amazonia, R. E. Dickinson, ed. New York: Wiley Interscience, 1987.
  4. Silva Dias P, and Avissar R. The Future of the Amazon: Impacts of Deforestation and Climate. Conference, unpublished proceedings. Smithsonian Tropical Research Institute, Panama, 2002.
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  6. Werth D. and Avissar R, The local and global effects of Amazon deforestation. Journal of Geophysical Research 2002, 107, 8037.

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