PollutionNatural disasters

Deforestation

PollutionPollution is the introduction of contaminants into an

environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms .[] Pollution can take the form of chemical substances, or energy, such as noise, heat, or light. Pollutants, the elements of pollution, can be foreign substances or energies, or naturally occurring; when naturally occurring, they are considered contaminants when they exceed natural levels. Pollution is often classed as point source or nonpoint source pollution. The Blacksmith Institute issues annually a list of the world's worst polluted places. In the 2007 issues the ten top nominees are located in Azerbaijan, China, India, Peru, Russia, Ukraine and Zambia

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Access to water supply and sanitation in El Salvador remains low, despite recent increases in coverage, which leads to negative impacts on productivity and health in particular of the rural poor. Water resources are heavily polluted and the great majority of wastewater is discharged without any treatment into the environment. Institutionally a single public institution is both de facto in charge of setting sector policy and of being the main service provider. Attempts at reforming and modernizing the sector through new laws have not borne fruit over the past ten years.

CUTUMAY CAMONES, El Salvador — This is a site of retching foulness where cows, children and vultures stand side by side, wrenching survival from a mountain of rotting animal corpses and human waste. Where flowering trees once sheltered flocks of fabulously colored birds that drank from clear, flowing rivers, a seemingly endless stream of trucks now disgorges cargoes of poisonous trash.

A natural disaster is the effect of a natural hazard (e.g. flood,(tornado) volcano eruption, earthquake, or landslide) that affects the environment, and leads to financial, environmental and/or human losses. The resulting loss depends on the capacity of the population to support or resist the disaster, and their resilience. This understanding is concentrated in the formulation: "disasters occur when hazards meet vulnerability." A natural hazard will hence never result in a natural disaster in areas without vulnerability, e.g. strong earthquakes in uninhabited areas. The term natural has consequently been disputed because the events simply are not hazards or disasters without human involvement.

Tornadoes Main article: tornado Different Types of Tornadoes Supercell Tornadoes Main article: Supercell Some of the most violent tornadoes develop from supercell

thunderstorms. A supercell thunderstorm is a long-lived thunderstorm possessing within its structure a continuously rotating updraft of air. These storms have the greatest tendency to produce tornadoes, some of the huge wedge shape. The supercell thunderstorm has a low-hanging, rotating layer of cloud known as a “wall cloud.” It looks somewhat like a layer of a layer cake that hangs below the broader cloud base. One side of the wall cloud is often rain-free, while the other is neighbored by dense shafts of rain. The rotating updraft of the supercell is seen on radar as a “mesocyclone.”

The tornadoes that accompany supercell thunderstorms are more likely to remain in contact with the ground for long periods of time -- an hour or more -- than other tornadoes, and are more likely to be violent, with winds exceeding 200 mph.

TsunamisThe tsunami caused by the December 26, 2004

earthquake strikes Ao Nang, Thailand.Tsunamis can be caused by undersea earthquakes

as the one caused in Ao Nang, Thailand by the 2004 Indian Ocean Earthquake, or by landslides such as the one which occurred at Lituya Bay, Alaska in.

Ao Nang, Thailand (2004). The 2004 Indian Ocean Earthquake created the Boxing Day Tsunami and disaster at this site.

Lituya Bay, Alaska (1953). A mega-tsunami occurred here, the largest ever recorded.

This would also fit within Land movement category because it starts with an earthquake.

Deforestation Deforestation is the clearance of naturally occurring forests

by the processes of logging and/or burning of trees in a forested area. There are several reasons deforestation occurs: trees or derived charcoal can be sold as a commodity and used by humans, while cleared land is used as pasture, plantations of commodities and human settlement. The removal of trees without sufficient reforestation has resulted in damage to habitat, biodiversity loss and aridity. It has adverse impacts on biosequestration of atmospheric carbon dioxide. Deforested regions typically incur significant adverse soil erosion and frequently degrade into wasteland.

Disregard or ignorance of intrinsic value, lack of ascribed value, lax forest management and deficient environmental law are some of the factors that allow deforestation to occur on a large scale. In many countries, deforestation is an ongoing issue that is causing extinction, changes to climatic conditions, desertification, and displacement of indigenous people.

Economic impact Damage to forests and other aspects of nature could halve living standards for

the world's poor and reduce global GDP by about 7% by 2050, a major report concluded at the Convention on Biological Diversity (CBD) meeting in Bonn.[56] 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.[57]

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.[58]

The new procedures to get amounts of wood are causing more harm to the economy and overpowers the amount of money spent by people employed in logging.[59] 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).[60

Historical causes Further information: Timeline of environmental events Prehistory Small scale deforestation was practiced by some societies for tens of thousands

of years before the beginnings of civilization.[61] The first evidence of deforestation appears in the Mesolithic period.[62] It was probably used to convert closed forests into more open ecosystems favorable to game animals.[61] With the advent of agriculture, larger areas began to be deforested, and fire became the prime tool to clear land for crops. In Europe there is little solid evidence before 7000 BC. Mesolithic foragers used fire to create openings for red deer and wild boar. In Great Britain shade tolerant species such as and ash are replaced in the pollen record by hazels, brambles, grasses and nettles. Removal of the forests led to decreased transpiration resulting in the formation of upland peat bogs. Widespread decrease in elm pollen across Europe between 8400-8300 BC and 7200-7000 BC, starting in southern Europe and gradually moving north to Great Britain, may represent land clearing by fire at the onset of Neolithic agriculture.

An array of Neolithic artifacts, including bracelets, axe heads, chisels, and polishing tools.

The Neolithic period saw extensive deforestation for farming land.[63][64] Stone axes were being made from about 3000 BC not just from flint, but from a wide variety of hard rocks from across Britain and North America as well. They include the noted Langdale axe industry in the English Lake District, quarries developed at Penmaenmawr in North Wales and numerous other locations. Rough-outs were made locally near the quarries, and some were polished locally to give a fine finish. This step not only increased the mechanical strength of the axe, but also made penetration of wood easier. Flint was still used from sources such as Grimes Graves but from many other mines across Europe.