And the other gloomy scenario is the thinning of ice. Arctic sea ice thickness has gone down from an average 9.8 ft.(3.1 m) during 1958-76 to an average 5.6 ft. (1.8 m) in 1993-97. Burning of forests to create croplands and unregulated timber harvesting has destroyed more than 15 per cent of Amazon in the last 30 years. Since 1945 the Antarctic peninsula has experienced a warming of about 4.5 degree Fahrenheit (2.5 degree centigrade) and the annual melt season has increased by about 2 to 3 weeks in just the past 20 years.

As limited amount of fresh water reaches people in each passing year, unequal access to supplies and water stress have triggered conflicts among nations. Consequently, hunger continues to plague poorer countries, especially in Africa and part of Asia. The future looks far more gloomy. Imagine a future of relentless storms and floods, heavily inhabited coastal regions inundated by rising sea-levels, fertile soils rendered barren by drought and the desert's advance, mass migration of environmental refugees and armed conflicts over water and other natural resources!

Other than the threat of greenhouse gases, there are gloomy predictions from other areas. According to the Washington based World Watch Institute, the world has lost 200 million hectares (500 million acres) of trees since 1972. The world's farmers, meanwhile, have lost nearly 500 million tons of topsoil, an amount equal to the tillable soil coverage of India and France combined. Lakes, rivers and even whole seas have been turned into sewer, waste and industrial dumps. And thousands of plant and animal species that shared the planet with humans have since disappeared. In short, we have converted woodlands and prairies to farmland all over the globe with Bangladesh topping the list. Our cities suburbs and malls have paved over natural communities and pollution and over-fishing are rapidly destroying our rivers, lakes and oceans.

As these ecosystems go down, we are losing perhaps 30,000 species of animals and plants a year, out of perhaps10 million total species, even though we still rely on at least 40,000 species for food, shelter, clothing and fuel. We rely on natural products to replenish genetic diversity in our crops and to produce new medicines. We rely on pristine ecosystems to replenish oxygen, regulate water cycles, control erosion, cycle essential nutrients and restock critical fisheries. We still need these things to sustain life. The irony is that our rampant success in living outside the world's ecosystems has put them all, and thus ourselves in jeopardy.

The land is even under greater pressure in Bangladesh where a population of 140 million crowds into a 65,000 km of land area. Rain running off deforested northern hills in India has badly eroded the soil and low-lying areas causing flood situation most of the time with no advance warning or predictions. Land holdings have shrunk and are now typically divided leaving only a scant share among the heirs. As the country's population has exploded, the land has been subdivided so many times that the tiny plots that they inherit may not be sufficient to feed even one in a family of five members. Intense competition to grab land by the stronger heirs and relations in the family or by the neighbours is one of several forces fanning conflicts and clashes that have even led to murders in the villages.

The thought that human race is running out of required land, at the first glance, may seem to be absurd. Indeed, the earth's entire population of 6 (six) billion people could stand upright anywhere in a space of 5,700,000 hectares but the fact is: people need extra room to roam and especially to grow food. Much of the world's land is too rocky or arid or salty for agriculture. And forests that haven't already been cut deserve protection : they harbour the habitats of earth's endangered wild life. Experience has shown our part of the world that destruction of forests can have disastrous consequences. Forests are vital watersheds that absorb excess moisture and anchor topsoil. Deforestation contributed to the droughts in Africa in the late 80s and the devastating mud slides in Rio de Janeiro in 1988 and the recent mud slides in Chittagong taking a heavy toll of human lives. In Costa Rica topsoil eroded from bald hills has threatened the life of an expensive hydroelectric dam.

With the supply of prime turf for farming so tight, the average amount of grain land per person has dropped in 30 years from more than 0.2 hectares to little more than 0.1 hectare. Happily, only a boom in agricultural productivity contributed by HYV seeds, fertilizer and pesticide (against insect attack) has kept the burgeoning population fed.

Much of the arable land becomes less arable day by day assaulted by urbanisation, chemical pollution, desertification and the overuse of limited water sources. Reports gleaned from a study made by the experts in the field of water resources engineering indicate that the underground water levels in the whole country has gone much lower. The exhaustion of land in some areas in south eastern part of the country, namely Comilla, Noakhali and Chittagong districts has created new class of displaced persons that experts call the environmental migrant. And while wars have always been fought over territory, the future may even see green 'wars' triggered by shortages of such basic resources as topsoil or water.

In the race for land lies the unprecedented explosion of human population. Historically known, it took the species about 1,50,000 years of fits and starts to reach one billion mark around 1800. Since then, an additional five billion have been added to the headcount and if this trend continued, the population could pass 10 billion before the middle of this century. The consequence has been the continued pressure on woodlands, especially the tropical forests that are the reservoirs of the majority of earth's animal and plant species. In about a decade since 1980, an estimated 8 per cent of the world's tropical forest cover was cut, burned or otherwise destroyed.

In the country, the massive assault on the Sundarbans, Madhupur forest and forest lands of Sylhet and Chittagong triggered mostly by the protectors of forests in exchange of hefty kick-backs has invited drought and hastened the desertification process of this already fragile land. Managed as a natural reserved forest since 1800, the Sundarbans has considerably shrunk and is now severely threatened. For an ecological balance, any country should have at least 25 per cent of its area under forest cover, whereas Bangladesh has now only 7 per cent. The loss of such irreplaceable biological treasure is disturbing the ecological balance. The impact of deforestation goes far beyond the felled trees.

As a region loses its forest it loses its ability to trap and absorb water, and so run-off from denuded woodland worsens the natural process of erosion. If at the same time, farmers harvest crop year after year the soil is constantly exposed to wind and water. Consequently, the world wears away 24 billion tons of topsoil a year. The extent of topsoil erosion in India, according to Dr. S. Swaminathan, a noted agricultural scientist, goes to the tune of six billion tons which converted into monetary loss stands at over Rs 1000 crore in Indian currency per year.

To meet the needs of the burgeoning population, farmers world over have boosted their yields and fought against desertification by using heavy doses of fertilizer and irrigation water and also pesticides to protect crop. But that strategy has been counterproductive. Agricultural chemicals may gradually poison the soil, and irrigation also deposits a harmful residue. When the water evaporates it leaves behind various salts. They contribute to the natural buildup of salty compounds in the soil and the salinisation process can ultimately render the land useless for farming.

The World Bank report in 1993 reveals that some degree of salinisation affects 28 per cent of US's irrigated land, 23 per cent of China's and 11 per cent of India's. With mounting concern plaguing the nations because of the shortfall in crop production, IFAD is emphasising sustainable approaches to agricultural intensification while promoting appropriate technologies, community empowerment, informed decision-making and policies that support NRM (national-resource management).

In an innovative project in Niger, irrigation work has been turned over to termites. The technique involves digging holes some 15-20 cm deep and then using the unearthed soil to build protective ridges around the hole. The hole bottoms are covered with manure, which becomes a breeding ground for termites. The termites bore through the hard-baked soil, producing a delicate network of tunnels. When the rains come, the holes and tunnels fill with water, and farmers plant millet or sorghum, their local variety of crops without having to overexert themselves. In Lesotho, the Machobane farming system, named after its local inventor replaces traditional mono cropping with intensive relay cropping along contours in order to control erosion and conserve moisture. It enhances soil fertility by using wood ash and farmland manure.

Leaving aside the population boom in third world countries, there is hardly any contradiction about the fact that world hunger has more to do with war, poverty, poor technical skill, and poor food distribution than with the failure of achieving needed production by the farmers. And the fact that remains as the core problem and which most people know is that this poverty can often be self-perpetuating rather than self-correcting. So says Robert Brinkman, Chief of the Land and Water Development Division of the UN-affiliated Food and Agricultural Organisation in Rome: "When people get poor, they put pressure on the land and then they get poorer."

With creation of FAO style "bottom up" programmes that induce villagers in using drought resistant crops through modest irrigation projects and reforestation efforts, such successes can be replicated on a global scale. But still the problem of controlling population will remain a core issue that has to be tackled with priority. Shockingly true, around the globe humans coming in swarms of settlers either here in the vicinity of the Sundarbans or in Indonesia or the Philippines or Brazil or Peru are slashing and burning huge swaths through the forest to create roads, towns and fields. They came to enjoy a promised land but they have produced a network of devastation.

Md. Asadullah Khan is a former teacher of physics and Controller of Examinations, BUET.