Deforestation is the conversion of forested areas to non-forest land for use such as arable land, pasture, urban use, logged area, or wasteland. Generally, the removal or destruction of significant areas of forest cover has resulted in a degraded environment with reduced biodiversity. In many countries, massive deforestation is ongoing and is shaping and geography.
Deforestation results from removal of trees without sufficient reforestation, and results in declines in habitat and biodiversity, wood for fuel and industrial use, and quality of life.
Economic impact
Historically utilization of forest products, including timber and fuel wood, have played a key role in human societies, comparable to the roles of water and cultivable land. Today, developed countries continue to utilize timber for building houses, and wood pulp for paper. In developing countries almost three billion people rely on wood for heating and cooking. The forest products industry is a large part of the economy in both developed and developing countries. Short-term economic gains made by conversion of forest to agriculture, or over-exploitation of wood products, typically leads to loss of long-term income and long term biological productivity (hence reduction in nature's services). West Africa, Madagascar, Southeast Asia and many other regions have experienced lower revenue because of declining timber harvests. Illegal logging causes billions of dollars of losses to national economies annually.
A new study found that the emerging market for carbon credits: "Deforestation in tropical countries is often driven by the perverse economic reality that forests are worth more dead than alive. But a new study by an international consortium of researchers has found that the emerging market for carbon credits has the potential to radically alter that equation." The new procedures to get the massive amounts of wood are causing more harm to the economy and over powers the amount of money spent by people employed in logging. According to a study, "in most areas studied, the various ventures that prompted deforestation rarely generated more than US$5 for every ton of carbon they released and frequently returned far less than US $1." The price on the European market for an offset tied to a one-ton reduction in carbon is 23 euro (about $35).
Characterization
Throughout most of history, humans have considered forest clearing as necessary for most activities besides forestry. In most countries, only after serious shortages of wood and other forest products are policies implemented to ensure forest resources are used in a sustainable manner. Typically in developed countries, as urbanization and economic development increases, land previously used for farming is abandoned and reverted to forests. Today, in the developed world, most countries are experiencing forest restoration and most losses in forest land are primarily driven by expanding urban areas.
In developing countries, human-caused deforestation and the degradation of forest habitat is primarily due to expansion of agriculture, slash and burn practices, urban sprawl, illegal logging, over harvest of fuel wood, mining, and petroleum exploration.
A NASA satellite observation of deforestation near Rio Branco in Brazil observed July 28 2000
Djouce Mountain, along with most of the island of Ireland, was systematically clear-felled during the 17th and 18th centuries, in order to obtain wood mainly for shipbuilding.
Pollutants
Before flue gas desulfurization was installed, the emissions from this power plant in New Mexico contained excessive amounts of sulfur dioxide.
There are many substances in the air which may impair the health of plants and animals (including humans), or reduce visibility. These arise both from natural processes and human activity. Substances not naturally found in the air or at greater concentrations or in different locations from usual are referred to as pollutants.
Pollutants can be classified as either primary or secondary. Primary pollutants are substances directly emitted from a process, such as ash from a volcanic eruption or the carbon monoxide gas from a motor vehicle exhaust.
Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone - one of the many secondary pollutants that make up photochemical smog.
Note that some pollutants may be both primary and secondary: that is, they are both emitted directly and formed from other primary pollutants.
