Deforestation

Over most of human history, the majority of the population has populated forested portions of the planet. The forest vegetated realms evolved in several climate types and they range from the tropical rainforests to the taiga. Deforestation is usually defined to mean the reduction of a forest’s canopy cover to below 10 percent of an area.

Over the extreme arcs of Earth’s history, areas have deforested because continental drift has moved regions into climate types not supportive of forests. So, too, ancient deforestations can be recognized as being caused by volcanic eruptions and explosions and, more extensively, by basalt flows covering hundreds of thousands of square kilometers. It is manifest that natural climate change causes some deforestation. The cold of the Pleistocene Epoch caused equatorward shifts in climate types, and forests died in places far from the actual continental ice sheets. In Sumatra and Borneo, the Pleistocene lowering of sea level by many tens of meters caused shallow seas to disappear to create a large peninsula connected to the Asian mainland and this peninsula became heavily forested. The rise of sea level after the Pleistocene flooded and deforested the area and it became sea bottom again. 

Thus, deforestation was ongoing far before the times dominated by humans. Humans have become inexorably intertwined with deforestation. With today’s rapid increase in world population, deforestation is of increasing concern. Earth is losing forest at the estimated rate of 24 hectares (60 acres) per minute. Geographically, there are significant differences in deforestation. South America has the greatest amount of deforestation per year while Africa has the greatest rate.

Brazil and Indonesia have the greatest total loss of forest while the central African country of Burundi has had recent deforestation estimated at about 9 percent per year. In some developed places such as the United States and the European Union there have been increases in forest cover. However, this does little to staunch the world trend. The largest remaining forested tracts are those associated with low densities of human habitation and inaccessibility. They include the boreal (northern) forests of Alaska, Canada, and Russia, and the remote tropical forests of the northwestern Amazon basin and the eastern Congo basin.