RAINFORESTS AND WORLD CLIMATE
Article written for: Sundance
Complex systems, a living being individually, plant and animal communities, ecosystems, biomes such as oceans or the rain forest, or the Ecosphere as a whole, are highly balanced systems with many internal and external interactions and control mechanisms, or feedback. Such systems tend toward stability. They can take a lot of battering, of abuse. Up to a point, after which they break down or settle into a lower level of dynamic equilibrium.
When we try to predict the behavior of such a system reacting on stress, we cannot indefinitely make linear extrapolations. The point of breakdown, or flipover, more often than not, is unpredictable, at least with the simplified models we are able to make of them.
A very crude metaphor for the kind of situation we may face is a ruler slowly being pushed toward and over the edge of a table. Suppose there is a very tiny midget sitting on the inner end. He does the pushing but he is too small to see the other end. From past experience he feels quite confident he can push forever. Suddenly, though, the ruler flips over and falls to the floor. During the fall, if he has time, he may become wiser, but it is of no avail, it is too late.
Just before the flipover, there may be a short period of swinging, during which, if action is taken rapidly, the ruler could be pulled back to safety. Could it be that Modern Industrial Society has already pushed things to the point where we now find ourselves in or very close to the winging phase?
World climate is an integral part of the circulation of the Ecosphere. In a more reverent way we may call her “Gaia”, as was suggested by William Golding, based on Lovelock’s theory that sees the Earth as a living System. Gaia is the poetic name the ancient Greeks gave the goddess of the Earth they normally called Geo, whence words such as Geography, Geometry, etc. Air and water recycle the resources that keep Life going, just as our blood constantly recycles nutrients and wastes in our body.
The range of temperatures within which Life can exist and flourish, that is, the range of temperatures that make biochemistry possible, the chemistry 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 an extremely narrow range, when compared to the temperatures that prevail in the Universe at large. The temperatures go from close to absolute zero, 273 °C below zero, in interstellar and interplanetary space or on our far out planets, such as Neptune and Pluto, to between four and five hundred degrees Centigrade on Venus; close to fourty degrees below zero in summer, at noon, on the equator on Mars; about six thousand degrees on the surface of our sun; close to twenty million degrees in its interior; much, much hotter in bigger stars, in Sirius, for instance, and up to hundreds of billions of degrees Centigrade in the furnaces of imploding stars, the supernovas. If we represented this existing range of temperatures on a line where every degree is one millimeter, the line would be several hundreds of thousands of kilometers long. It would reach far beyond the Moon. The range propitious to Life – from a few degrees below zero, where Life survives by resting, to about eighty degrees above zero for a few organisms, some bacteria and algae that manage to live in hot springs, which makes a total of about one hundred degrees – when plotted against that line - would cover ten centimeters. Ten centimeters on several hundred thousand kilometers!
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, from what we know about its evolution, that the sun is today between one and a half and two times as hot as it was when Life began to structure itself in the primeval oceans. Our planet could have ended up in a situation of runaway greenhouse effect, like Venus. A little cooler, but still around two hundred degrees above zero. The oceans would have evaporated.
Or, if 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.
So, there is much more to climate than the greenhouse effect or the ozone hole.
Reacting to worldwide concern over the devastation of the rainforest, the Brazilian government likes to argue that we shouldn’t really worry. After all, the contributions of forest burning in Amazonia to the increase in atmospheric carbon dioxide is less than twenty percent of total. Absurdly linear thinking, indeed! But very common among those who have the power to act, who could make things change before it is too late.
Even if we look at only rainforests, we are dealing with several of the important factors controlling world climate. The rainforest is much more than just a repositary or sink for carbon dioxide, up to one thousand tons a hectare.
The rainforests, where the highest precipitations on Earth occur, also have an incredibly intense evapo-transpiration. This is the sum of evaporation and transpiration. Of the rain that goes down on dense rainforests, as was shown by Prof. Eneas Salati from the University of São Paulo, Piracicaba – Brasil, about 25% never reaches the ground. It is just enough to wetten foliage in the immense canopy and is evaporated into the air. Of the 75% that reach the ground only one third, that is another 25% of total, ends up in streams and rivers and goes back to the ocean. 50% of total are pumped up and transpired. So, 75% of rainwater is returned to the atmosphere to make new clouds, new rain, new clouds and so forth.
Now let’s look at the Amazonian rainforest in its entirety. Suppose, we make a diagram, showing a cross section of South America: the Pacific Ocean on the left; the Andes mountain chain, the Amazonian plains, the Atlantic on the right.
We can draw in the low flying clouds coming from the Atlantic with the trade winds. The first rains go down on the eastern plains, on Pará and Maranhão. Much of the rainwater goes back up, forms new clouds and farther west, new rain, new clouds, new rain, new clouds, new rains and so forth. By the time it rains on the eastern slopes of the Andes, it is water that went up and down between five and seven times. The rainforest makes its own climate and is the result of that climate. No use asking, what came first, climate or forest? It would be like asking, what came first, hen or egg?
One of the great ironies of the Modern Industrial Society with its technological sophistication is that we now can see the planet as a whole, nobody can clear a hectare of forest or plant an acre of corn without a computer console in the space laboratories of the great powers and some smaller ones showing it. Yet, down here, we continue behaving as if we were blind. Let’s look at Amazonia from a satellite perspective. What we can see, if we keep looking for days or weeks, is amazing and very revealing.
The air masses, as shown by the cloud movements, traveling into central South America from the Atlantic, go west and hit the mountain chain of the Andes. There, the flow splits into three branches. The central part jumps over the mountains into the Pacific and continues west along the Equator, roughly following the convergence of the warm northern sea current, El Niño, with the cold Humboldt stream that comes from the south. A system of interconnected ocean streams and air streams responsible for the incredible richness of life in and above the waters of the coast of Peru and where in the last two decades we have already had serious flipovers that caused overnight collapse of the fishing industry.
The Andes also seem to redirect an important part of the air masses to the south, over the central Brazilian Cerrado (savannah) and all the way down to Patagonia.
Another branch goes north, crosses the Caribbean, licks the eastern coast of North America and, in step with the Gulf Stream, reaches and penetrates Northern and Central Europe.
Perhaps we should now have a closer look at the Globe: Stockholm, Helsinki, Hamburg, Edinburgh are as far north as Labrador. Skandinavia and Northern Europe have long cold winters but they are quite livable; Labrador is tundra and taiga.
Could it be that the ice ages these regions went through four times in the Pleistocene, the geological period that ended about ten thousand years ago, had to do with disturbances in the Gulf Stream and the air currents? We know the different lengths of the four great glaciations, Guentz, Mindel, Riss and Wuerm, from tens of thousands to hundreds of thousands of years. Could they really have been caused solely by astronomical events with exact periodicities, as is often claimed?
We know that glaciations, once they are triggered, develop quite rapidly, almost over night, but it takes that infinity of time, in human terms, for them to taper off again. How did the mammoth get trapped alive in thick sheets of ice and then rest there like frozen meat for thousands of years?
Paleobotanists tell us that the spreading out of the Amazonian rainforest is concomitant with the tapering off of the last glaciation in the northern hemisphere. Before that, the immense area that is now rainforest, where it hasn’t been devastated yet, was mostly savannah. The rainforest ecosystems were confined to “islands” in higher places, where the clouds hit the mountains.
On the extremely dry Venezuelan peninsula of Paraguaná I saw such an island of humid forest on the peak of Santana Mountain. The peak is brushed by the low flying clouds of the trade winds. The spreading out and coalescing of many such islands may be at the root of the incredible diversity of life forms in Amazonia. Even though the forest is contiguous over five million square kilometers, there is an incredible number of endemisms. An endemic species is a life form with a very limited area of occurrence. The spacial distribution of many related species in Amazonia in some ways reminds one of Darwin’s finches on the Galapagos Islands, all come together.
Could it be pure coincidence that the rainforest spread while the ice retreated?
Let’s forget the metaphor of the rainforest as “the lung of the planet” or its “oxygen factory”. Ecosystems in climax, that is in final equilibrium, procure as much oxygen as they consume. Oxygen is not the most pressing problem, when we are concerned with the rainforest. But the loss of species diversity is. It is of extreme importance. When a species goes, it goes forever, the Universe will be poorer.
Unfortunately, tough, the powerful are not easily impressed by arguments like this one. I have heard some of them say, so what if a few butterflies and frogs go? They need something of more immediate urgency. Fortunately, governments of the most powerful nations are now worrying about the climate crisis and paying at least lip service to the necessity of stopping the devastation of the Amazon rainforest. They must know that the rainforest has to do with climate in more ways than just the carbon dioxide balance in the atmosphere.
What if the rainforest disappears? As we saw above, the forest makes its own climate and is the result of the climate. What if devastation continues at the present rate in the east, in the states of Pará and Maranhão, where, at the present rate of clearings, everything could be gone by the year 2000 or 2010; in the west, in Rondônia, northern Mato Grosso, Acre and the state of Amazonas; in the north, in Roraima, in Amapá, and all around the south, in the transition forests, between rainforest and Cerrado? A hundred thousand square kilometers of primeval forest cleared every year and growing exponentially. The size of Portugal! Another total of over 100.000 square kilometers of secondary vegetation also burned off every year. Devastation is still being subsidized by our irresponsible government and, it seems, Japan wants to make a loan of two and a half billion dollars to the Brazilian government. An “unspecified” loan. We all know what the Japanese want and what our government and some greedy individuals want: the prolongation of the BR 364 road from Acre to a Pacific port in Peru. The idea is to make timber exports to Japan and China possible. If that road is opened, Acre will become a new Sarawak. The “National Council of the Rubber Tappers” is desperately fighting against this road, and so are the Indians. What if devastation reaches 20% or more, especially with so much of it occurring in the east, at the beginning of the chain of rain recycling? There is a possibility of the remaining forest collapsing!
The savannah forests, even when the vegetation is only low bushes and scrub, has very deep going roots. It can stand long periods of draught. The rainforest has extremely superficial roots. This is because there are almost no nutrients in the soil and the soil has no nutrient holding capacity. Recycling of nutrients is vital and is almost immediate. The dead leave falling on the ground is literally “eaten up” by the hairroots that come out of the soil in symbiosis with certain fungi. There is almost no litter on the ground and there is no humus. This kind of forest cannot stand prolonged spells of drought. Even if it does not die quickly, it may become combustible. The standing rainforest with its present climate cannot burn. For burning it must be felled.
We can already observe certain types of forest collapse in Amazonia. In some lower flood plains the forest is dying, without anybody setting chainsaw to it or spraying “defoliant”. The flow regime of the river has changed because of the clearings in the west. The length and depth of the annual flooding was altered in such a way that the existing plant community cannot survive.
So, long before all the forest is cleared, a point of no return may have been past and collapse will proceed. Like the midget on the ruler, we will only know when it is too late.
And what will happen if the rainforest collapses? Several important factors for climate control will be profoundly affected: carbon dioxide increase will get a tremendous additional push, the fantastic evapotranspiration, that is, the colossal heat pump that sends energy from the Equator to higher latitudes, north and south, will cease functioning. Salati worked out that the daily energy turnover is equivalent to six million atom bombs. In its place there will be a strong albedo returning solar energy to space and the torrid ground will make hot updrafts that dissolve incoming clouds, instead of making new ones. The present positive feedback for more rain will turn into a positive feedback for more drought, and what with the proverbial south American pyromania that sets fire to everything in the landscape that can burn? And, one more factor that should not be taken too lightly: resistance of the forest to wind. Open fields, deserted areas or even scrub vegetation have much less effect on the winds than has the deep tall forest. Lovelock, in his studies has also gone into the governing effects of rare gases in the atmosphere. Very low concentrations of certain gases such as methane, ammonia, sulfur and nitrogen oxides, also resins and aromatic gases exuded by the forest in extremely low concentrations, may have controlling effect on the cycles of more abundant gases. For instance, why is it that photosynthesis, now operating for close to two and a half billion years has not pushed oxygen concentration beyond the present 21% which would be catastrophic? At 30% even the wet rainforest could burn and one lightning could trigger its total destruction. Or, why hasn’t respiration lowered oxygen concentrations to dangerous levels? There is some control mechanism, or mechanisms, we know very little about.
As far as we know, the models the climatologists are making of world climate, of which they themselves insist they are incomplete and rivaling models are possible, do not yet include the disappearance of the rainforests of the world.
But, do we need more information in order to act? It is a common tactic of technocrats and bureaucrats to ask for more research when they are subjected to public pressure for the pollution they cause. While that research proceeds, they continue dumping their dirt into the environment.
We know we are messing up all the mechanisms of climate control, the ones we know and those we don’t: carbon dioxide, ozone, aerosols, dusts, cloudiness, evapotranspiration, albedo, wind resistance, methane, nitrogen and sulfur oxides, freons, hydrocarbons, etc. etc. How long can we abuse the system? How long will it take for Gaia to catch fever? Do we really have to know all the details in order to act?
If 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 territories. An exacerbation of the climatic irregularities we already have will soon leave us in a situation where we cannot count on safe harvests anymore. We are now over five billion people. Food reserves are getting shorter. What good would nice beach weather be on Spitzbergen, if we have nothing to eat? And what about the social calamities and upheavals that will result, with guys like Kaddafi and others having access to ABC-weapons?
What for Gaia in her lifespan of ten billion years, with at least another five billions to go, may be a soft and momentary fever, could be the end of civilization for us.
A wise person may risk learning from mistakes, but will avoid experiments where, if 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?
José A. Lutzenberger
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