Humankind began in an extensively forested world. As population increased, different types of deforestation arose. People cleared forests for agriculture, grazing, firewood, and buildings, which are still the major causes of deforestation, along with logging, mining and land development. Long-term changes in climate and fires also play a part.

The United Nations Food and Agriculture Organization estimates that originally, forests covered about 45 percent of earth's land masses, and now forests only cover 31 percent. The World Wildlife Fund states that forests are disappearing at the rate of 46-58 million square miles annually, which is the equivalent of 36 football fields per minute.

In the humid tropics, indigenous people clear forests by cutting down trees and burning them, called slash-and-burn practices. They plant crops in the cleared land and farm for a few years, and when the land becomes unproductive, it is abandoned and the process repeats. Since the 1960s, the Amazon rain forest has seen increased use of this technique. A 1994 study cited in "Slash-and-Burn Agriculture" attributes 30 percent of South America's deforestation to this practice.

High demand for commodities such as soy, wood pulp and palm nut oil leads to forest destruction and replacement with plantations. Sumatra and Borneo have lost over half the rainforest that existed only 30 years ago to palm oil and acacia tree plantations. Oil palm fruits yield oil used in cooking and cosmetics. World palm oil production increased from 1.7 million tons in 1961 to 64 million tons in 2013. Acacia trees provide wood for pulp and paper products. Vast areas of Brazil's rainforests are being converted to soybean crops due to high world market prices and demand from China.

A result of population increase is deforestation. One of many examples of deforestation resulting from a population rise is China, which went from about 1.4 million people 4,000 years ago and over 60 percent forest coverage, to 65 million in 1368 with 26 percent forest coverage. By 1949, China had more than 541 million people and only 10 percent coverage. Two thousand years ago, Europe had forests on over 80 percent of the land, compared to today's 34 percent coverage. Deforestation fueled the industrial revolution until fossil fuels became available.

Tropical rainforests yield hard woods with unusual colors and grain, such as mahogany, teak and ebony. Greatly in demand for furniture and cabinetry, many tropical trees are now considered endangered species because of population reduction. Most countries with harvestable hardwoods have strict logging laws, but illegal logging still occurs. Deforestation is hastened not only by removal of trees but by road-building to access them, which encourages soil erosion, flooding, forest fragmentation, thinning and drying of remaining forests and greater fire susceptibility. Roads also open forests to greater development and use.

Forest destruction threatens the wildlife and people who depend upon its resources. In Sumatra and Borneo, tigers, rhinoceroses, and orangutans have greatly decreased numbers. People are dispossessed of their land and their livelihoods. Species diversity declines. About 15 percent more carbon dioxide gets released due to deforestation, exacerbating climate change. You can help by recycling, purchasing only legal hardwoods, supporting local and global conservation efforts, using alternative energy sources and purchasing items that come from sustainable, renewable sources.