Among other things, the longer summers, and the delay and change in rainfall patterns leave no doubt that the Earth's climate is gradually changing. Earth's climate and biosphere are influenced by the increasing concentrations of certain gases that have the potential to transform significantly the planet's heat and radiation balance. Among these are carbon-dioxide, methane and nitrous oxide, and some trace gases in the atmosphere. Such alteration of Earth's heat and radiation balance is leading to a warmer climate, a process that may quicken in the next century. The point of concern is that this change in climate will have a serious impact on all life forms on land and the aquatic biosphere, including human civilisation.

Historically, the invaluable life support systems of Earth have largely been ignored till it came under severe threat. For example, deforestation has only now underscored the critical role forests play in regulating the water cycle — in particular, in mitigating floods, droughts, the erosive forces of wind and rain, and silting of dams and irrigation canals/channels. Today, the escalating impact of human activity on forests, wetlands, and other ecosystems imperil the delivery of such services. The primary threat is posed by land-use changes that result in a loss in biodiversity as well as disruption of carbon, nitrogen, and other bio-geochemical cycles; by human-caused invasions of exotic species; by the release of toxic substances; and by the depletion of the stratospheric ozone.

There is no alternative to society having a clear idea of its dependence, or impact, on Earth's natural resources.

The consequences

The scientific assessments of the utilisation pattern of these resources and its consequences on the various ecosystems must be understood. We must know how the loss of 30-50 per cent of Earth's species will affect the world's economic growth and the health of humans? Why is there a rise in Earth's average surface temperature and how has it started affecting the global climate? What is the nature of the negative impact of the increase of different harmful gases in the atmosphere? How has the loss of wetlands affected the lives of millions of poor people? What are the consequences of over-exploitation of the world's major freshwater and marine fisheries? How is soil-erosion related to food insecurity?

The average adult breathes more than 3,000 gallons of air daily. The global vehicle population is more than 730 million, which is increasing everyday and their emissions poison the atmosphere. Increasing air pollution is not only harming human health but also damaging various ecosystems and their functions.

Although energy is central to modern human existence, the negative impact of its production, distribution and use has grown exponentially. Using fossil fuels depletes a non-renewable source of energy and emits air pollutants, and processing those fuels produces greenhouse gases, including carbon-dioxide. World carbon-dioxide emissions are projected to rise approximately 50 per cent to 37.1 billion tonnes by 2025, with large increases expected from developing nations such as China and India.

Water is an important component of Earth and life is totally dependant on it. Although water covers 70 per cent of the planet's surface, only 2.5 per cent is freshwater, and of this only about one per cent suitable for human use. We are polluting our freshwater systems faster than ever before. The growing human population is depleting groundwater faster than it can be replenished.

According to a 2005 report by the Millennium Ecosystem Assessment, a United Nations-associated programme, the ecosystems have changed more quickly and extensively in the past 50 years than in any other period. Natural ecosystems perform fundamental life-support services without which human civilisations would cease to thrive. These eco-systems services are being provided to us free of cost and include purification of air and water, detoxification and decomposition of wastes, regulation of climate, regeneration of soil fertility, and production and maintenance of biodiversity, from which key ingredients of our agricultural, pharmaceutical, and industrial enterprises are derived.

Economic impact

Biodiversity is important to the global economy as it contributes greatly to pharmaceutical industries, agriculture, horticulture, fisheries and nature tourism. Similarly, biodiversity is essential for ensuring food security of the planet's growing population. Plant-breeding using wild genetic stock is responsible for high agriculture yields in many developed and developing nations.

However, the Millennium Ecosystems Assessment states that about 60 per cent of the world's ecosystems are being degraded. Industrial activity affects ecosystems through pollution emissions, waste discharges and consumption of natural resources such as trees. Other reports reveal that human activity has damaged more than half the world's coastal ecosystems, and about 230 million acres of forestland have been lost during the past decade.

More than 11,000 species are listed as endangered. We are endangering our own future by degrading the environment and over-exploiting the natural resources.

Humanity came into being after most ecosystem services were available for hundreds of millions of years. These services are so fundamental to life that they are easy to take for granted, and they are so large in scale that it is hard to imagine that human activity can irreparably disrupt them.

Scientists are indicating the ramifications of climatic change and the loss of natural resources. There is no choice before planners and policy-makers but to act expeditiously.

It is a matter of urgency that appropriate policies and action plans are framed and implemented, both at the national and international levels, for a more secure future of all species, including man.

(The author, based in Kolkata, is a member of the Indian Forest Service.)