Resource depletion

There are many different groups interested in depletion accounting. Environmentalists are interested in depletion accounting as a way to track the use of natural resources over time, hold governments accountable or to compare their environmental conditions to those of another country.[4] Economists want to measure resource depletion to understand how financially reliant countries or corporations are on non-renewable resources, whether this use can be sustained and the financial drawbacks of switching to renewable resources in light of the depleting resources.[4]

Depletion accounting is complex to implement as nature is not as quantifiable like cars, houses or bread.[4] For depletion accounting to work, appropriate units of natural resources must be established so that natural resources can be viable in the market economy. The main issues that arise when trying to do so are, determining a suitable unit of account, deciding how to deal with "collective" nature of a complete ecosystem, delineating the borderline of the ecosystem and defining the extent of possible duplication when the resource interacts in more than one ecosystem.[4] Some economists want to include measurement of the benefits arising from public goods provided by nature, but currently there are no market indicators of value.[4] Globally, environmental economics has not been able to provide a consensus of measurement units of nature's services.

One of the main causes of deforestation is clearing forests for agricultural reasons. As the population of developing areas, especially near rainforests, increases, the need for land for farming becomes more and more important.[19] For most people, a forest has no value when its resources are not being used, so the incentives to deforest these areas outweigh the incentives to preserve the forests. For this reason, the economic value of the forests is very important for the developing countries.[20]

Because deforestation is so extensive, it has made several significant impacts on the environment, including:

• Carbon dioxide in the atmosphere
• Changing the water cycle
• An increase in soil erosion
• A decrease in biodiversity

Deforestation is often cited as a contributor to global warming. Because trees and plants remove carbon dioxide and emit oxygen into the atmosphere, the reduction of forests contribute to about 12% of anthropogenic carbon dioxide emissions.[21] One of the most pressing issues that deforestation creates is soil erosion. The removal of trees causes higher rates of erosion, increasing risks of landslides, which is a direct threat to many people living close to deforested areas. As forests get destroyed, so does the habitat for millions of animals. It is estimated that 80% of the world's known biodiversity lives in the rainforests, and the destruction of these rainforests is accelerating extinction at an alarming rate.[22]

The United Nations and the World Bank created programs such as Reducing Emissions from Deforestation and Forest Degradation (REDD), which works especially with developing countries to use subsidies or other incentives to encourage citizens to use the forest in a more sustainable way.[23] In addition to making sure that emissions from deforestation are kept to a minimum, an effort to educate people on sustainability and helping them to focus on the long-term risks is key to the success of these programs.[24] The New York Declaration on Forests and its associated actions promotes reforestation, which is being encouraged in many countries in an attempt to repair the damage that deforestation has done.[25]

Some of the world's most successful agricultural areas are wetlands which have been drained an converted to farmland for large-scale agriculture.[26] Large-scale draining of wetlands also occurs for real estate development and urbanization.[28] In contrast, in some cases wetlands are also flooded to be converted to recreational lakes or hydro-power generation.[26] In some countries ranchers have also moved their property onto wetlands for grazing due to the nutrient rich vegetation.[28] Wetlands in Southern America also prove a fruitful resource for poachers, as animals with valuable hides such a jaguars, maned wolves, caimans and snakes are drawn to wetlands.[28] The effect of the removal of large predators is still unknown in South African wetlands.[28]

Humans benefit from wetlands in indirect ways as well. Wetlands act as natural water filters, when runoff from either natural or man-made processes pass through, wetlands can have a neutralizing effect.[29] If a wetland is in between an agricultural zone and a freshwater ecosystem, fertilizer runoff will be absorbed by the wetland and used to fuel the slow processes that occur happen, by the time the water reaches the freshwater ecosystem there won't be enough fertilizer to cause destructive algal blooms that poison freshwater ecosystems.[29]

Bramiana Wetlands

• Hydrologic alteration [26]
  • drainage
  • dredging
  • stream channelization
  • ditching
  • levees
  • deposition of fill material
  • stream diversion
  • groundwater drainage
  • impoundment
• Urbanization and urban development
• Marinas/boats
• Industrialization and industrial development
• Agriculture
• Silviculture/Timber harvest
• Mining
• Atmospheric deposition

To preserve the resources extracted from wetlands, current strategies are to rank wetlands and prioritize the conservation of wetlands with more environmental services, create more efficient irrigation for wetlands being used for agriculture and restricting access to wetlands by tourists.[28]

Groundwater is considered to be a non-renewable resource because less than six percent of the water around the world is replenished and renewed on a human timescale of 50 years.[33] People are already using non-renewable water that is thousands of years old, in areas like Egypt they are using water that may have been renewed a million years ago which is not renewable on human timescales.[32] Of the groundwater used for agriculture 16 to 33% is non-renewable.[34] It is estimated that since the 1960s groundwater extraction has more than doubled, which has increased groundwater depletion.[34] Due to this increase in depletion, in some of the most depleted areas use of groundwater for irrigation has become impossible or cost prohibitive.[35]

Overusing groundwater, old or young can lower subsurface water levels and dry up streams, which could have a huge effect on ecosystems on the surface.[32] When the most easily recoverable fresh groundwater is removed this leaves a residual with inferior water quality. This is in part from induced leakage from the land surface, confining layers or adjacent aquifers that contain saline or contaminated water.[35] Worldwide the magnitude of groundwater depletion from storage may be so large as to constitute a measurable contributor to sea-level rise.[34]

Currently, societies respond to water-resource depletion by shifting management objectives from location and developing new supplies to augmenting conserving and reallocation of existing supplies.[35] There are two different perspectives to groundwater depletion, the first is that depletion is considered literally and simply as a reduction in the volume of water in the saturated zone, regardless of water quality considerations.[35] A second perspective views depletion as a reduction in the usable volume of fresh groundwater in storage.[35]

Augmenting supplies can mean improving water quality or increasing water quantity. Depletion due to quality considerations can be overcome by treatment, whereas large volume metric depletion can only be alleviated by decreasing discharge or increasing recharge.[35] Artificial recharge of storm flow and treated municipal wastewater, has successfully reversed groundwater declines.[35] In the future improved infiltration and recharge technologies will be more widely used to maximize the capture of runoff and treated wastewater.