¨ Environmental goods and services may be classified as either renewable or nonrenewable.
¨ A renewable
resource can regenerate if it is alive, or can be replenished by biochemical cycles
if they are nonliving.
A tree is an example of a renewable resource,
because a new tree can grow in place of an old tree that dies or is cut down.
¨ A renewable resource is not necessarily unlimited.
¨ Fresh water can easily become limited by drought or overuse.
A nonrenewable resource is one that cannot be replenished by
Fossil fuels-coal, oil, and natural
gas are nonrenewable resources. When they are depleted, they are gone forever.
¨ Sustainable development is a way of using natural resources without depleting them, and
providing for human needs without causing long-term environmental harm.
¨ Human activities can affect the quality and supply of renewable
resources such as land, forests, fisheries, air, and fresh water.
¨ Sustainable strategies must enable people to live comfortably and
improve their situation.
¨ The use of insects to control insect pests is one such strategy. This may help farmers reduce the use of pesticides.
¨ Land is a resource that provides space for human communities and
raw materials for industry.
¨ Land also includes the soils in which crops are grown.
¨ The most fertile soil is in the uppermost layer called topsoil.
¨ Such soil is produced by long-term interactions between the soil
and plants growing in it.
¨ Plowing the land removes the roots that hold the soil in place.
¨ Soil erosion is the wearing away of surface soil by water and wind.
Ø The Midwest loses roughly 47 metric tons of topsoil per hectare every year!
¨ In dry climates, a combination of farming, overgrazing, and drought
has turned once productive areas into deserts a process called desertification.
¨ There are a variety of sustainable-development practices that guard
against these problems.
Ø Contour plowing, in which fields are plowed across the slope of
the land to reduce erosion.
Ø Leaving the stems and roots of the previous year’s crop in
place to help hold the soil.
Ø Planting a field with rye rather than leaving it unprotected from
Ø Forests have been called the “lungs of the Earth” because
they remove carbon dioxide and produce oxygen.
Ø Forests provide:
Ø Wood for homes, paper, fuel
Ø Store nutrients
Ø Provide habitats and food for organisms
Ø Moderate climate
Ø Limit soil erosion
Ø Protect freshwater supplies
¨ Worldwide, about half of the area originally covered by forests
and woodlands has been cleared.
¨ Only about one-fifth of the world’s original old-growth forests
¨ Deforestation or the loss of forests can lead to severe erosion as soil is exposed to heavy rains.
¨ Erosion can wash away nutrients in the topsoil.
¨ Grazing or plowing after deforestation can change local soils and
microclimates that may prevent regrowth of trees.
¨ There are a variety of sustainable-development strategies for forest
Ø Mature trees are harvested selectively to promote growth of younger
trees and promote the forest ecosystem.
Ø Foresters plant, manage, harvest, and replant tree farms.
Ø Tree geneticists are also breeding new, faster-growing tree varieties
that produce high quality wood.
Ø Fishes and other animals that live in water are a valuable source
of food for humanity.
¨ Overfishing, or harvesting fish faster than they can be replaced
by reproduction, greatly reduced the amount of fish in parts of the world’s ocean.
¨ From 1950-1990, the world fish catch grew from 19 million tons to
more than 90 million tons.
¨ By the early 1990’s, populations of cod and haddock had dropped
so low that researchers thought these fish might disappear.
¨ The declining fish populations are an example of the “tragedy
¨ “Tragedy of commons” is when people from several countries
take advantage of a resource but no one takes responsibility for maintaining it.
Because of the declining fisheries, the U.S. National
Marine Fisheries Service created guidelines for United States
The guideline specified how many fish, and of what
size, could be caught in various parts of the oceans.
¨ The regulations are helping fish populations to recover.
¨ Unfortunately, it caused loss of jobs in the short term, but will protect the
fishing industry for the future.
Ø Aquaculture is the raising of aquatic animals for human consumption.
Ø It also helps to sustain fish resources.
Ø If it is not managed properly, aquaculture can pollute water and
damage aquatic ecosystems.
¨ Air is a resource that affects people’s health and it’s
quality remains a challenge for modern society.
¨ Smog is a mixture of chemicals that occurs as a gray-brown haze in the atmosphere.
¨ Smog is due to automobile exhaust and industrial emissions.
¨ Smog is considered a pollutant.
¨ A pollutant is
a harmful material that can enter the biosphere through land, air, or water.
¨ The burning of fossil fuels can release pollutants into the atmosphere.
¨ Toxic chemicals are nitrates, sulfates, and particulates which are
microscopic particles of ash and dust.
¨ Most industries have to control their emissions from factory smokestacks.
¨ Strict automobile emission standards and clean-air regulations have
greatly improved air quality in U.S. cities.
¨ The release of nitrogen and sulfur compounds into the atmosphere
when combined with water vapor form strong acids.
¨ When acid rain falls, it can kill plants and change the chemistry
of soils and standing-water ecosystems.
¨ Americans use billions of liters of freshwater daily for drinking
and washing to watering crops and making steel.
¨ Pollution threatens water supplies in several ways.
Ø Improperly discarded chemicals can enter streams and rivers.
Ø Waste discarded on land can seep through soil and enter groundwater.
Ø Domestic sewage (sinks and toilets) which contain nitrogen can encourage
growth of algae and bacteria in aquatic habitats.
Ø Sewage containing microorganisms can spread disease among humans
¨ One way of ensuring the sustainable use of water resources is to
protect the natural systems involved in the water cycle.
Ø Wetlands help to purify the water passing through them. Densely growing plants filter certain pollutants out of the water.
Ø Forests and other vegetation help to purify the water that seeps
into the ground.
¨ Water conservation is becoming an increasingly important aspect
of sustainable development.
¨ More than three quarters of all water consumed is used in agriculture.
Ø An example of conservation would be to use drip irrigation which
delivers water directly to plant roots. This reduces the amount of water lost