Exploitation of Natural Resources | CUET PG Geography | Notes

Impact of Human Activities on the Environment

Human activities have fundamentally transformed the Earth’s physical environment since the onset of settled agriculture roughly ten thousand years ago, but the scale, intensity, and pace of this transformation have accelerated dramatically since the Industrial Revolution of the eighteenth century, and even more sharply since the mid-twentieth century — a period of such rapid and pervasive human-driven change that many earth scientists now refer to the current geological epoch as the “Anthropocene,” signifying that human activity has become the dominant force shaping geological and ecological processes at a planetary scale. Among the many forms of human intervention in nature, deforestation, mining, agriculture, and industrialisation stand out as the four most consequential drivers of environmental change, each operating through distinct mechanisms but often interacting synergistically to produce compounded and sometimes irreversible degradation of land, water, air, biodiversity, and climate systems.

Deforestation

Deforestation refers to the large-scale, permanent removal of forest cover, typically for conversion to agricultural land, pasture, urban settlement, or infrastructure. It is estimated that the world has lost roughly one-third of its original forest cover since the advent of agriculture, with the pace of loss accelerating enormously in the twentieth and twenty-first centuries, particularly across the tropical forests of the Amazon basin, the Congo basin, and Southeast Asia, which together host the majority of the world’s remaining primary tropical forest and the greatest concentration of terrestrial biodiversity.

Causes of deforestation are varied and often interlinked. Agricultural expansion is the single largest driver globally — this includes both large-scale commercial agriculture (soybean cultivation and cattle ranching in the Brazilian Amazon, oil palm plantations in Indonesia and Malaysia) and smaller-scale shifting cultivation or slash-and-burn agriculture practised by subsistence farmers in tropical regions, including parts of Northeast India. Commercial logging and timber extraction, often unsustainable and sometimes illegal, remove valuable hardwood species and frequently open up previously inaccessible forest to further encroachment via logging roads. Mining and mineral extraction require clearing of forest cover both for the mine site itself and for associated infrastructure. Infrastructure development, including road construction, dam building, and urban expansion, fragments and removes forest cover, while fuelwood collection, especially in developing countries where a large share of the rural population still depends on wood for cooking and heating, contributes to forest degradation, particularly around densely populated areas.

The environmental consequences of deforestation are extensive and multidimensional. In terms of biodiversity, deforestation causes habitat destruction and fragmentation, pushing countless plant and animal species toward extinction — since tropical rainforests, despite covering only about 6-7% of the Earth’s land surface, are estimated to harbour over half of the world’s terrestrial species, their clearance represents one of the primary drivers of the ongoing sixth mass extinction. In terms of the hydrological cycle, forests play a crucial role in regulating rainfall through transpiration (the “biotic pump” effect, especially significant in the Amazon, where a substantial share of regional rainfall is recycled through the forest canopy itself); their removal disrupts local and regional precipitation patterns, reduces infiltration and groundwater recharge, increases surface runoff, and consequently increases the frequency and severity of both floods (due to reduced interception and infiltration) and droughts (due to reduced moisture recycling). In terms of soil, the removal of the protective forest canopy and root systems dramatically accelerates soil erosion, as exposed topsoil is washed away by rainfall or blown away by wind, leading to loss of soil fertility, siltation of rivers and reservoirs (reducing their water-holding capacity and lifespan), and in severe cases, desertification. In terms of climate, forests function as major carbon sinks, absorbing atmospheric carbon dioxide through photosynthesis and storing it in biomass and soil; deforestation not only eliminates this ongoing carbon sequestration capacity but, particularly when forests are cleared through burning, releases enormous quantities of previously stored carbon directly into the atmosphere as carbon dioxide, making deforestation and land-use change collectively responsible for a substantial share (commonly estimated around 10-15%) of global anthropogenic greenhouse gas emissions, thereby directly contributing to global warming and climate change. Deforestation also disrupts local microclimates, since forests moderate temperature extremes and humidity; cleared areas typically experience greater diurnal and seasonal temperature variation. Finally, deforestation has severe socio-economic consequences for indigenous and forest-dependent communities, who lose access to timber, non-timber forest produce, medicinal plants, and the cultural and spiritual significance embedded in forest landscapes, often precipitating displacement and conflict.