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cal services performed by ecosystems or on the social and psychological security provided by vernacular human societies; and which, above all, is incompatible with ecological and social security.

There can be few better illustrations of the irrationality of the modern market system than the forces that drive pasture-led deforestation. It matters not a jot that cattle bring few direct profits, nor that the land is so severely degraded that eventually it must be abandoned, nor that the ecological degradation is eventually translated into direct economic costs — be it through climatic change, soil erosion or the disruption of hydrological cycles. For the system allows profits to be made regardless of this devastation — the profits coming through land speculation. Within that context, clearing land for pasture will always be the favoured "economic" option, regardless of the unassailable ecological and social argu­ ments in favour of keeping the forests standing. Moreover, so long as the underlying political dynamic behind pasture led clearance remains unaddressed, the threat to the forests will remain.

The changes required will demand more than mere tinkering with the system. Interna­ tional trade, and the consumer society that feeds it, ensure that we are all parties to the destruction. The beef mountains of Europe have been fed on soyabean grown on land in the south of Brazil, from which peasants have been dispossessed and sent as colonists into the forests. Aluminium cans which end up on our rubbish dumps come from smelters fed with bauxite from Amazonia and powered by dams such as the Tucurui, which flooded some 216,000 hectares of forest. And so on. In this respect, the saving of Amazonia relies as much on the international community adopting policies that reduce the ecological impact of their activities as on any measures that can be taken within the Amazonian nations themselves.

Signs of Hope

Given the enormity of the changes required — changes that will affect everything we do — it would be understandable if the determination to save the forests gave way to despair and resignation. But, despite the gloom, there is light at the end of the tunnel. The case for extractive reserves is now gaining ground. Recent research in Peruvian Amazonia has documented the tremendous economic value to be derived from exploiting the non-timber products of /ntecnropical forests. The research shows that the income per hectare from "minor' forest products (nuts, rubber and the like) is two times higher than from logging the land, and three times higher than that from conversion to pasture for cattle (though the effects of land speculations were not taken into account).

Even more encouraging, the Colombian Government has set a remarkable precedent for Amazonian countries by granting inalienable land rights to its indigenous forest peoples. Some 18 million hectares — two-thirds of Colombian Amazonia and an area equivalent to the size of Great Britain — have been handed over, or are in the process of being handed over. Moreover, it is a policy based not on political expediency but on the belief that the Indians are the best guardians of the forest (see P. Bunyard, this issue).

Finally, forest groups throughout Amazonia, from rubber-tappers to Indians, are suc­ cessfully taking up the fight to preserve the forests and their ways of life. Theirs is a dangerous struggle: witness the murder of Chico Mendes (see book reviews, this issue). But, like antibodies in a diseased body, they signal hope for the future — and with it the possibility of regeneration.

In that respect, it is worth recalling the words of the anthropologist Margaret Mead: "Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has." Daunting as the task ahead might seem, individual actions — through lobbying, changing lifestyles, political action, boycotts and the like—. can make a difference. But only if we are willing to act. And act now, before it is too late.

Nicholas Hildyard

What you can do: • Support the World Rainforest Movement's Appeal to the United Nations for an Emergency

Meeting on Deforestation (see this page) • Write to President Virgilio Barco of Colombia (Palacio Presidential, Carrera Otavo 7-26,

Bogata, Colombia) expressing your support for their decision to hand over land to indige­ nous forest peoples. • Support Friends of the Earth (26-28 Underwood Street, London N1) in its campaigns to

save the tropical rainforests, and the Gaia Foundation (18 Well Walk, London, NW3) which is channelling funds directly to forest peoples' projects in Amazonia and S.E. Asia.

• The Manifesto, together with a 50-page briefing document on the causes and consequences of forest destruction are available from: The Ecologist, Station Road, Sturminster Newton, Dorset, DT10 1BB, UK. Price: £3.00 (plus 50 pence postage and packing).

Call for UN Emergency Session on

Deforestation

Three Million Signatures Presented to UN

On September 19th, representatives of forest peoples from Brazil, The Philip­ pines, India and other Third World countries presented 3 million signa­ tures, collected from 23 countries, to Perez de Cuellar, Secretary-General of the United Nations, in support of a call for an emergency session of the UN to consider ways to put an end to global deforestation. The petition, launched by The Ecolo­ gist in 1987, was presented in conjunc­ tion with a Manifesto, drawn up by the World Rainforest Movement, calling for an immediate halt to those projects which are causing the runaway de­ struction of tropical and temperate forests (see editorial). At first Perez de Cuellar refused to re­ ceive the petitions, claiming to be too busy. The response was a sit-in in the main lobby of the UN building. After an hour, the Secretary-General agreed to receive a delegation from the organ­ izers of the campaign and representa­ tives from tribal groups.

The international organisers of the petition campaign — the World Rain­ forest Movement, based in Penang, Malaysia and Ecoropa, the European Ecological Action Group, based in Paris—plan to follow up the initiative with two further campaigns: 1. At the national level, groups which

participated in the campaign are being urged to lobby their national governments to back the call for an emergency session of the UN; 2. At the international level, a working

party has been set up to help co­ ordinate a coherent grassroots re­ sponse to the forest crisis and to draw up, through local forest peoples' groups, detailed regional proposals to combat deforestation. The aim is to put forward a "Peoples'" alternative to the Tropi­ cal Forestry Action Plan and other top-down "solutions" being im­ posed by the international devel­ opment community.

Nicholas Hildyard

210

The Ecologist, Vol. 19, No. 6, November/December 1989 The Amazonian Forests and Climatic Stability

by Luiz Carlos B. Molion

The forests of Amazonia play a critical role in regulating climate at both the regional and global levels. Massive quantities of carbon are locked up in the forest biomass, which, if released, would add considerably to global warming. Moreover, the forests act to pump heat into the atmosphere, cooling the tropics and distributing heat to temperate zones. At the local level deforestation may increase temperatures, decrease rainfall and

disrupt hydrological cycles.

The Earth's climate depends on several 'climatic controls'. Thus, the global dis­ tribution of the energy received from the sun is controlled by orbital parameters, such as the angular velocity and inclina­ tion of the Earth's rotational axis, cloudi­ ness and the chemical composition of the atmosphere. The distribution of continents and oceans with their contrasting albedos (surface reflectivities) also has a control­ ling influence.

The above controls, in turn, influence the mechanisms that move heat from the equator towards the poles — the general circulatory system of the atmosphere — which plays an important role in maintain­ ing global climatic stability. A t the regional level, a number of other factors are also operative, including, the nature of the surface cover; the hydrological cycle; the local topography; and the influence of oceanic currents on adjacent land.

Amazonia and Temperate Climates

The sun is the most important source of en­ ergy sustaining life. The bulk of the solar energy reaching the Earth's surface is spent in the evaporation of water (genera­ ting latent heat) and in heating the air (producing sensible heat). I n Central Amazonia, research has shown that about 80 per cent of the available energy is used in evapotranspiration (evaporation plus plant transpiration), while the rest warms the air.1 Over terra firme forest — that is the upland forest which is never flooded — the bulk of the water vapour in the air comes either from the transpiration of

Luiz Carlos B. Molion is at the Institute for Space Studies (INPE), CP. 515, 12.201 Sao Jose dos Campos, Sao Paulo, Brazil.

plants (60 per cent) or from rainfall inter­ cepted by the forest canopy and litter layer (40 per cent). Direct soil evaporation is negligible. The annual mean evaporation in Amazonia is about 50 per cent of the total rainfall, that is, half of the rainfall falling over Amazonia comes from local evaporation and the other half from the At­ lantic Ocean.2 By comparison, in tem­ perate latitudes loca l evaporation contributes about 10 per cent of precipita­ tion.

In the tropics, the evaporation process consumes about 2.44 joules per gram of water, an enormous amount of energy con­ sidering that, on average, the Earth re­ ceives 2.94 joules of energy per centimetre square per day. The humid and hot air is more buoyant and rises; when it rises, however, i t cools, forming cumulonimbus clouds and rain, thus releasing to the at­ mosphere the latent heat that was used in the evaporation at the surface. As the cu­ mulonimbus clouds grow, more vapour is converted into liquid water and the whole atmospheric column is heated.

The rising air is replaced at low altitudes by air coming from the oceans (conver­ gence); at altitudes of around ten kilome­ tres the ai r is transported away (divergence) from the continent and sinks over the subtropical oceans thus closing a circulation cell. Figure I sketches this circulation cell. For demonstration pur­ poses, the direct circulation is broken into two components: the east-west compo­ nent, known as the Walker Circulation and the equator-tropics component, known as the Hadley Circulation. Figure 2 shows schematically how these two circulation cells are major components of the general circulatory system of the atmosphere. Note that along the equatorial belt, there are three regions where there is ascending air motion (figure 2a): the 'Maritime Con­

tinent' (Indonesia and the North of Austra­ lia), the Congo River Basin and the Ama­ zon River Basin.

A fourth heat source, of no less import­ ance, is the Intertropical Convergence Zone (ITCZ) which is a region over the equatorial oceans where the Trade Winds of both hemispheres meet. In the ITCZ re­ gion, there is ascending air motion, forma­ tion of a deep cloud band and rainfall: consequently, large amounts of latent heat are released to the atmosphere. That re­ leased heat is transported away from the tropics by the general circulatory system of the atmosphere to temperate and polar regions, which would otherwise be colder because they receive less energy from the sun than they lose to outer space. Thus, the global climate remains stable with annual variations which may be due to fluctua­ tions in these heat sources.

The Amazon is an important source of heat for the general circulatory system of the atmosphere. Large-scale deforestation may reduce the power of this source. As mentioned previously, about 50 per cent of Amazonian rainfall comes from water vapour which is evaporated locally. De­ forestation reduces evapotranspiration, therefore reducing precipitation and the release of latent heat. Thus, as a result of large-scale deforestation in Amazonia, those regions outside the tropics may re­ ceive less heat and become cooler than they are today, everything else remaining constant. Cooling of higher latitudes would result in a reduction of the growing season, affecting food production.

Amazonia and the Chemical Composition of the Atmosphere

Amongst the gases which constitute the Earth's atmosphere are a group known as

The Ecologist, Vol. 19, No. 6, November/December 1989

211