FORESTS

A forest is defined as an environment that is covered by trees at least five meters (16 feet) high over an area of at least 0.5 hectares (1.2 acres)—a bit smaller than the size of an American football field. Forests grow in cold, temperate, and tropical regions and cover about 30 percent of the land area around the globe. They provide resources for humans, including food, timber, energy, shelter, and medicine. The trees in forests help purify water by filtering pollutants from water in the soil before it reaches a waterway. In addition, trees store carbon from the atmosphere and provide supportive environments for plants and animals.

 

Because forest ecosystems are so valuable to the planet, scientists and policymakers are concerned about their maintenance and health. The Food and Agricultural Organization of the United Nations produces a report every five years on the state of forests around the globe. They use surveys from scientists on the ground and remote sensing of forests from space to calculate any losses or gains in forest coverage. They also use the data to monitor the overall health of forests.

 

Forests have long been under assault by loggers and people clearing land for agriculture. They have also been disappearing because of natural causes, such as climate change, forest fires, and the death of trees from disease or insects. Between 1990 and 2015, the area occupied by forests worldwide decreased by one percent, with most of the losses occurring in the tropics. Scientists predict that as human populations rise, deforestation to convert tropical forests to agricultural land will undoubtedly continue.

 

There have, however, been increases in the size of some forests, often because trees in those areas were replanted. Forests can also naturally replenish themselves if the land is nurtured and protected from any further timber harvesting.

Slowing the loss of forests, experts say, will require countries and communities to develop effective forest management plans. Such plans, they say, must strike a balance between environmental protection and the economic needs of human society.

Deforestation is the purposeful clearing of forested land. Throughout history and into modern times, forests have been razed to make space for agriculture and animal grazing, and to obtain wood for fuel, manufacturing, and construction.

 

Deforestation has greatly altered landscapes around the world. About 2,000 years ago, 80 percent of Western Europe was forested; today the figure is 34 percent. In North America, about half of the forests in the eastern part of the continent were cut down from the 1600s to the 1870s for timber and agriculture. China has lost great expanses of its forests over the past 4,000 years and now just over 20 percent of it is forested. Much of Earth’s farmland was once forests.

 

Today, the greatest amount of deforestation is occurring in tropical rainforests, aided by extensive road construction into regions that were once almost inaccessible. Building or upgrading roads into forests makes them more accessible for exploitation. Slash-and-burn agriculture is a big contributor to deforestation in the tropics. With this agricultural method, farmers burn large swaths of forest, allowing the ash to fertilize the land for crops. The land is only fertile for a few years, however, after which the farmers move on to repeat the process elsewhere. Tropical forests are also cleared to make way for logging, cattle ranching, and oil palm and rubber tree plantations.

 

Deforestation can result in more carbon dioxide being released into the atmosphere. That is because trees take in carbon dioxide from the air for photosynthesis, and carbon is locked chemically in their wood. When trees are burned, this carbon returns to the atmosphere as carbon dioxide. With fewer trees around to take in the carbon dioxide, this greenhouse gas accumulates in the atmosphere and accelerates global warming.

 

Deforestation also threatens the world’s biodiversity. Tropical forests are home to great numbers of animal and plant species. When forests are logged or burned, it can drive many of those species into extinction. Some scientists say we are already in the midst of a mass-extinction episode.

 

More immediately, the loss of trees from a forest can leave soil more prone to erosion. This causes the remaining plants to become more vulnerable to fire as the forest shifts from being a closed, moist environment to an open, dry one.

Climate change is a long-term shift in global or regional climate patterns. Often climate change refers specifically to the rise in global temperatures from the mid-20th century to present.

 

Climate is sometimes mistaken for weather. But climate is different from weather because it is measured over a long period of time, whereas weather can change from day to day, or from year to year. The climate of an area includes seasonal temperature and rainfall averages, and wind patterns. Different places have different climates. A desert, for example, is referred to as an arid climate because little water falls, as rain or snow, during the year. Other types of climate include tropical climates, which are hot and humid, and temperate climates, which have warm summers and cooler winters.

 

Climate change is the long-term alteration of temperature and typical weather patterns in a place. Climate change could refer to a particular location or the planet as a whole. Climate change may cause weather patterns to be less predictable. These unexpected weather patterns can make it difficult to maintain and grow crops in regions that rely on farming because expected temperature and rainfall levels can no longer be relied on. Climate change has also been connected with other damaging weather events such as more frequent and more intense hurricanes, floods, downpours, and winter storms.

 

In polar regions, the warming global temperatures associated with climate change have meant ice sheets and glaciers are melting at an accelerated rate from season to season. This contributes to sea levels rising in different regions of the planet. Together with expanding ocean waters due to rising temperatures, the resulting rise in sea level has begun to damage coastlines as a result of increased flooding and erosion.

 

The cause of current climate change is largely human activity, like burning fossil fuels, like natural gas, oil, and coal. Burning these materials releases what are called greenhouse gases into Earth’s atmosphere. There, these gases trap heat from the sun’s rays inside the atmosphere causing Earth’s average temperature to rise. This rise in the planet’s temperature is called global warming. The warming of the planet impacts local and regional climates. Throughout Earth’s history, climate has continually changed. When occurring naturally, this is a slow process that has taken place over hundreds and thousands of years. The human influenced climate change that is happening now is occuring at a much faster rate.