India is on the verge of an ecological disaster, says a World Bank (wb) report. By the year 2020, the study predicts that sulphur dioxide emissions in the country would increase by 315 per cent. The study, "Rains-Asia: An Assessment Model for Acid Deposition in Asia," says that this increase is much above the critical load level. If the same trend continues for 23 years, then China, India and several other South Asian countries will be afflicted by sulphuric acid deposition on its water bodies, forests and buildings.

Sulphur dioxide reacts with the moisture in air and forms sulphuric acid. High concentration of sulphuric acid in acid rain makes soil infertile and unsuitable for agriculture. The rain can pose major health risks for humans. The study, based on model simulation, warns that emissions for Asia as a whole will register an increase of 228 per cent. While China's emissions of sulphur dioxide is set to increase by 177 per cent in the same period, Pakistan's emissions will be the highest in the region showing an increase of 1126 per cent.

1. Parts of Europe and Asia including China will see more acidification in their environment in the coming years.

2. Agricultural land will expand from approximately 37 per cent of the total land area presently to around 50 per cent by 2050. The highest increases are projected to take place in Africa and West Asia.

3. The total global water demand will grow substantially from 3,000 km 3 in 1990 to 4,300 km 3 in 2050.

4. Life expectancy is expected to reach a global average of just over 70 years by 2050 compared with 75 years or more today in developed countries. The future years could foresee a population that is on average wealthier and in better health, but living in a world with scarcer resources.

5. With the world economy increasing maybe five-fold and the need to reduce environmental pressures by at least by a factor of two for many problems, the efficiency of resource use should be increased ten-fold globally in the coming half-century.

These are the shocking results of a recent draft of a model-based study of the state of global environment. The world environment has undergone a major change ever since industrialisation began to feature as an important cornerstone of national economic policies. In their quest to become rich, countries turned a blind eye towards the environment. It was only in the past few decades that a green sense enveloped nations and an ecological perspective began to surface as a serious global concern. The Rio summit in 1992 resulted in the formation of Agenda 21, the global action plan for promoting sustainable development.

In response to Agenda 21, the un Environment Programme (unep) initiated a new biennial reporting series called the Global Environmental Outlook (geo). The geos are aimed at supporting the implementation of Agenda 21 by monitoring its progress, assessing the state of the environment, identifying emerging issues and giving support to priority issues for international action. As a contribution to the first georeport, rivm or the Dutch National Institute of Public Health and Environment, one ofunep"s collaborating centres has made a model-based assessment of future global environment according to a "Conventional Development" (cd) scenario (see box: As is where is), developed by the Stockholm Environment Institute (sei). This scenario with a time frame up to ad 2050, is based on an extension of historical developments and trends, assuming no major social, political, technical or natural surprises or disruptions. On the basis of the modelling tools available, the assessment of the future state of the global environment focused on two important areas of interaction between socio-economic developments and the environment, namely, (a) global and regional cycles of carbon and sulphur emissions and (b) the use of land and water resources.

The geo assessments project a not-so-green future for the world. Major findings indicate that environmental pressures will build up accompanied by a change in climate; acidification will become a serious problem in some developing regions; freshwater scarcity will aggravate; and, with agricultural land expanding, the natural habitat for preserving biodiversity will shrink.

Acid rain: first-degree burns on nature

The problem of acidification arises when two key conditions are met: first, a region has a high level of economic activity with intensive use of fossil fuels leading to large atmospheric emissions of acidifying pollutants. These emissions must be large enough to be transported through the atmosphere for long distances in significant quantities. The second condition is that soil, forest and aquatic ecosystems in a region are susceptible to these acidifying pollutants. Recent assessments have identified the northern and central parts of Europe, the eastern part of China and the southern parts of Asia as regions at the greatest risk of damage as a result of acidification. In the case of Asia, even with the partial controls assumed in the cdscenario, the critical loads for sulphur deposition are still expected to be exceeded substantially. Consequently, woodlands in some of these developing areas could deteriorate more rapidly, endangering agricultural production and the supplies of fuelwood and other products. The acid deposition can lead to the release of toxic metals to ground and surface water, further contaminating drinking water supplies. Clearly, if there are no controls the negative effects of acidification in Asia would be much worse.

A change for the worse

Up to now, most impact assessments of climate change have centred on industrialised countries at medium and high latitudes. This is partly because computer models predict that the largest temperature changes are likely to occur at these latitudes, but also since most research focuses on those regions where more research funds are available. Nevertheless, models also indicate that developing countries in low latitudes may experience important changes in climate, including crucial rainfall patterns.

Acidification and climate change have the same root cause, namely a high level of economic activity that results in emissions of huge amounts of polluting substances into the atmosphere. Many of these pollutants stem from the same source - burning of fossil fuels. In 1990, this accounted for over 80 per cent of the global emissions of carbon dioxide and about 94 per cent of the European emissions of sulphur dioxide (so2) the main cause for acidification of Europe"s environment. The two environmental issues are not only related with respect to their causes, but also with respect to their impacts. Recently, a better understanding has emerged as to how these two problems interact. The emissions of acidifying pollutants, especially so2, lead to accumulation of particles in the upper atmosphere which partly mask the global warming caused by greenhouse gases (ghgs). If the level of particles in the atmosphere is assumed to remain constant at their 1990 marks, the growth in ghgs would increase the global average surface temperature by about 1.5

FOR the past 10 years, a large number of moose are dying in southwest Sweden. The cause for this is acid rain. Acidification and the declining numbers of this warm-blooded animal are being linked because of a complex chain of events, arising from the occurrence of the former.

According to Adrian Frank of the Centre for Metal Biology in Uppsala, Sweden, acid rain is indirectly responsible for the fatalities. To counter the effect of acidification on the environment, liberal sprayingof lime is a standard practice in the country. Since the early '80s-, wetlands, lakes, fields, pastuies and even some forested regions hav@ been limed following their acidification.

4 Ironically, it is the lime which has lead to an imbalance in the concentration of chemicals like copper and molybdenum in the animals' livers. The useof lime was intensified in the mid'80s which corresponded with the time kFn a large number of the animals began signaling the coming disaster as they contracted some diseases. The acid rain led to the destruction of blueberry bushes (staple diet of the moose), and the animals changed their feeding habits. They turned to cultivated pastures and fields of oat and rape, which were being heavily lithed by the farmers.

Frank explains that as and when acidification occurs, it decreases the PH level of the soil, and metals such as cadmium, zinc and, manganese - as a result of capillary action - move up to the top soil, getting ingested by herbivores in greater quantities. But molybdenum being less soluble in an acid-rich environment, stays put at a lower level. With the spraying of lime (done to neutralise the soil), the process reverses so that the plants now receive an overdose of molybdenum, while chemicals like cadmium become scarce. According to Frank, this excessive amount of molyb - denum plays havoc with the copper content in the ruminants' diet, decreasing it to such an extent as to lead to cop- per deficiency, which can at times prove fatal. The animals appear gaunt, and sport discolored hair and impaired immune systems. They tend to suffer from osteoporosis, ulcers, diarrhoea, convulsions, blindness and heart failures.

In 1982, Frank had collected liver and kidney samples from 4,360 moose, shot by hunters in Sweden. His study of 14 chemicals revealed that the copper content had gone down by 50 per cent in- the livers of the animals, but the quantity of molybdenum was up by 20- 40 per cent. There were significant changes in the concentrations of other elements like chromium, whose level was found to be extremely low too. "The condition of their kidneys also indicate severe metabolic disturbances due to the reductions in cadmium, magnesium and manganese," says Frank.

In a paper to be published by the American Chemical Society, Frank extols the virtue of the moose as an environmental benchmark. Since the moose live on a large variety of plants, they can be useful as reliable and sensitive indicators of environmental changes, providing information on the changes in the levels of all metals.

Frank believes that the people responsible for liming should realise the environmental consequences of doing so not only from the point of view of the plants, but also of the animals consuming them. But the Swedish Environmental Protection Agency has rejected his call for an urgent nationwide investigation on the probable effects of liming on wildlife. Alternate theories project the possibility of overpopulation or a viral attack, as being responsible for the declining numbers of the moose.

IN JAPAN, elementary school magazines have been selling particularly well recently due to the mini easy-to-use acid rain measuring kits attached to the inside of the magazines' back cover. A chemical is placed in a small plastic container. When acid rain falls on it, the color changes, and from this the acidity content in the rain can be read.

Readers send back these figures to the publishers. In 1994 summer, some 51,000 observations were returned, and this year almost the same number have been returned by elementary schoo)goers, Based on these results, a national acid rain intensity map is likely to be charted.

Acid rain has been frequent in Japan as it had been in Northern Europe and North America, and now it has become just as noticeable. Should it continue, its influence may well become widespread as may concerns about it.

Japan's Environment Agency has established a national monitoring network. Records from 1994 show that the Ph (acidity or alkalinity of a solution/soil expressed numerically) in rainfall in 28 places averaged 4.8 with acidic rainfalls reported in both urban and rural areas ranging between Ph 4.5 -to 5.8. The situation has remained constant for 10 years.

J. Acid deposition has degraded lakes, swamps and wetlands to such an extent that organisms cannot thrive in northern European waters. According to an Environment Agency survey, almost all rivers, lakes and marshes in Japan have a Ph of around 7.0, but some with low Ph levels were also found.

The Japanese government has recognized that deterioration, drying and death of greenery has occurred nationwide, and in 1994, the Agency said it could not deny that acid rain was responsible for this situation. This was the first time the government has officially recognized these adverse environ- mental impacts.

In 1958, factories of the Yokkaichi industrial complex in central Japan, generated air pollution due to S04 resurting in decreased harvests of wet rice. In other words, air pollution had a negative impact on vegetation, and in 1961, many people developed breathing difficulties and other- health problems. Tetsuro Taniyarna of Mie University reported that an S04 concentration of 0.02 per cent per month would have a negative impact on vegetation growth.

Winter winds blow from Asia eastward over the adjacent seas and lands so that so2 emissions from China and the Korean Peninsula are carried across the Sea of Japan to Japan, Japan's close neighbour China alone produces 2,000,000 torme/year of so, today.

THERE has been a reduction in the emissions of the oxides of sulphur and nitrogen, but the observed decrease in the acidic content of precipitation is less than expected.

According to a recent study, the decrease hasn't come about because of the decline in the atmospheric concentration and deposition of "cations" -- positively charged atoms -- of calcium, magnesium, potassium, and sodium, which chemically neutralise acid rain (Nature, Vol 367, No 6461).

Acid rain occurs when the oxides of sulphur and nitrogen, which are emitted when fossil-fuels like oil are burned, dissolve in the atmospheric moisture which condenses into rain. Acid rain leads to the acidification of streams and lakes, affecting aquatic plants and animals, sometimes even killing off fish stocks.

It has also been implicated in the destruction of forests, although acid rain expert Eville Gorham of the University of Minnesota holds that the deleterious effects of acid rain "on terrestrial ecosystems are less clear, but may be substantial".

The effects of acid rain are diluted by cations present in flyash from urban and industrial smokestacks, particles of wind-borne soil and cement dust, all of which are alkaline in nature. Ammonia from nitrogenous fertilisers also finds its way into the atmosphere, and this too can neutralise acid rain.

But according to Lars O Hedin and his colleagues from Cornell University who undertook an analysis of cation concentrations, there has been a sharp decline in concentrations over the past 10 to 26 years. In the Netherlands, for example, there was a 32 per cent decrease in cation concentration from 1978 to 1987; in Sweden, the decrease was as much as 74 per cent from 1971 to 1989. In the US, at the Hubbard Brook Experimental Forest where atmospheric chemical constituents are measured, a decline of 48 per cent from 1965 to 1989 was observed.

Hedin and his colleagues found that the decrease in cation concentrations is linked to a decline in the emissions of particulate matter from regional urban and industrial sources, and emissions from non-point sources such as unpaved roads. In Sweden, such emissions were reduced by as much as 80 per cent from 1960 to 1980, and in the Netherlands, concern for pollution led to a 63 per cent reduction in dust emissions from 1970 to 1990.

Ironically, efforts to check particulate emissions, says Gorham, have lead to an increase in acid rain, and environmentalists will now have to call for a yet more stringent regulation of sulphur dioxide -- the main acid rain culprit.

THE errant ways of humans have the most unexpected effects on ecosystems. Ecologists J Graveland and his colleagues at the Netherlands Institute of Ecology say that air pollution and the subsequent acid rain have had enormous impact on the reproduction of a common European bird -- the great tit (Nature, Vol 368, No 6470).

The scientists observed that the great tits (Parus major) in the Buunderkamp forest in The Netherlands, have been increasingly laying defective eggs. The proportion of the birds laying defective eggs increased from 10 per cent in 1983-84 to as much as 40 per cent by 1987-88. The defective shells were thin and porous, and had a rough surface. The scientists observed that these eggs failed to hatch because they tended either to dry up or break. And, interestingly, almost half the female great tits with damaged eggs deserted their nests.

Because all defects were linked to the shells of the birds' eggs, calcium deficiency appeared a likely cause. And sure enough, scientists found that most defective eggs were found in forest regions with poor soils, deficient in calcium. The calcium needs of female great tits are predominantly met by feeding on snails, whose shells have a high calcium content. But the scientists found that in forests with poor soils, the number of snails was meagre.

The scientists found that on poor soils the snail populations have decreased substantially over the years, whereas an attendant decrease in snail numbers on calcium-rich soils was not observed. A similar decline was also observed on poor soils in Sweden.

Snails require calcium obtained by eating soil and rock in addition to their regular food, and by absorption through their skin, to build their shells. Acid deposition, the scientists explain, has previously been implicated in a reduction in soil calcium -- through leaching -- in poor soils. This calcium deficiency, passed on through the snails, has an impact on the birds which are the next link in the food chain.

The scientists found that the calcium content of great tit food in forests on rich soils -- where the birds' eggs were usually normal -- was 50 per cent more than that of great tits living in poor soil regions. And on feeding caged birds snail shells and chicken egg shells, they found that there was a reduction in the number of empty nests, unhatched eggs and nest desertions.

The climate over parts of Turkey was severely affected in 1991-92 by heavy smoke billowing from Kuwaiti oil-wells set ablaze in the Gulf War. Hunay Evliya, a chemistry professor in the southern Turkish town of Adana, said the smoke led to black rain and the winter was the coldest recorded in Turkey (Environment, Science and Technology, Vol 26 No 5). A lot of snow fell on the normally subtropical Mediterranean coasts of Turkey, Syria and Lebanon in January and February this year.

Black rain fell in Turkey for a few days after the oil-fields were set afire and sunshine decreased by 25 per cent. Huge clouds of smoke rose to a height of 3 km and travelled eastwards. A cyclonic whirl over the eastern Mediterranean collected soot, oil and other constituents of the burning oil in the lower levels of the atmosphere and this fell as black rain. Turkish scientists found the rain contained several substances present in Kuwaiti oil. The effects were also seen a year later.