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PIMR HUMAN INTERACTION WITH ENVIRONMENT
Transcript of PIMR HUMAN INTERACTION WITH ENVIRONMENT
The Earth's resources, environment and human populations are interconnected. People use the resources for energy and raw materials to sustain life and to create wealth. These activities have an impact on the natural and human-built environments.
For example, agriculture has disrupted the natural systems of the earth from the time it was first practiced.
In 1950, the harvest of fish from the world's oceans was 19 million tonnes, rising to nearly 90 million tonnes by the end of the twentieth century.
The same impact can be shown with water, soil, forests, minerals, and energy resources.
We have caused harmful changes in the
- the zone of earth, air, and water in which we live.
Population and Resources
Each year nearly 80 million people are added to the world's population, putting ever more pressure on the Earth's natural systems. Yet much of the increase is in the developing world, so the impact is not as great as if it had occurred in the developed world.
If even a fraction of the increase in population in the developing world lived like most people in the industrialized world, pollution and waste levels could overwhelm the Earth's natural systems.
Human activities inflict harsh and often irreversible damage on the environment and on critical resources. If not checked, many of our current practices put at serious risk the future that we wish for human society and the plant and animal kingdoms, and so may alter the living world that it will be unable to sustain life in teh manner that we know.
- World Scientists' Warning to Humanity (1992)
Since 1962, when Rachel Carson published "Silent Spring," there have been many international meetings that have discussed sustainability.
The United Nations Commission on the State of the Environment (1987) asked for people in the developed world to reduce resource consumption and develop a sustainable lifestyle.
The report said that the developing world would need to reduce population growth.
In 1992, at the Earth Summit at Rio de Janeiro, a statement of action called Agenda 21 was produced, calling for a sustainable world economy. There has been little progress in slowing the environmental trends seen at Rio as a threat to the well-being of the planet.
Water: The Indispensable Resource
Only 3% of the water in the world is fresh water. Nearly 78% of that is in the form of ice caps and glaciers, and much of the remaining amount is underground as ground water.
The United States, China, and India are all facing reduced groundwater supplies.
An aquifer is an underground layer of rock that allows water to flow through it. If the flow of water is stopped by a layer of impermeable rock, the aquifer holds underground water supplies.
The supply of groundwater is constant and can be pumped whenever a farmer needs it, and is cheaper to access than surface water.
It does not need to be stored in costly containers and is not subject to high rates of evaporation.
The problem is that, unlike surface supplies, aquifers do not recharge rapidly. There can be serious environmental and health consequences if the water table is allowed to fall too low.
In India, water tables are falling by one to three metres per year and wells are running dry. Aquifer depletion could reduce India's harvest by one-fourth.
Surface waters are also being abused. They have been used for disposal of sewage and agricultural and industrial wastes.
On Canada's east and west coasts, Victoria and Halifax dump untreated wastes into surrounding waters.
Beluga whales in the St. Lawrence River and sturgeon in the Fraser River are threatened by water polluted by industrial, agricultural, and human wastes.
Sustainable water management can be realized with present technology. Large-scale projects can be replaced by micro-dams, hydro systems that run with a river's natural flow, shallow wells, and more efficient rainwater harvesting.
As technologies develop, an increase in the use of reclaimed or recycled water and desalinated seawater will help.
Low energy sprinkler systems and drip irrigation could be used in agriculture world-wide.
In industrialized countries, industrial and domestic use can be reduced through more efficiency. Taxes or user rates could be introduced to encourage users to conserve groundwater.
Agenda 21 is a completely non-binding international framework for sustainability passed in 1992 at the Rio Earth Summit. The framework, which sets out very loose aspirational goals for making communities more efficient and less carbon-intensive, was signed by then President George H.W. Bush and later upheld by Presidents Bill Clinton and President George W. Bush.
Since the framework was adopted, right-wing conspiracy theorists have pushed bizarre theories about Agenda 21 being a central tool for the United Nations to create a one-world government and take away the rights of local property owners. In recent years, elevated by the megaphone of extreme pundits like Glenn Beck and Rush Limbaugh, these conspiracies made their way into mainstream politics. Today, Agenda 21ers — many affiliated with the Tea Party and the John Birch Society — are peddling fears about Agenda 21 in order to stop basic efficiency and renewable energy programs on the state level.
Change is in the Air
The ozone layer is a thin layer of ozone (O3), a special kind of oxygen, in the atmosphere 15-50 km above the Earth's surface.
Ozone is the only gas in the atmosphere that can block the ultraviolet (UV) rays of the sun. UV radiation can cause skin cancer in humans and can damage other animal and plant species.
In the 1980s, it became apparent that the ozone layer was thinning.
Chemicals, particularly chlorofluorocarbons (CFCs), which have done 80% of the damage, are destroying the ozone layer.
CFCs have been widely used since the 1930s in coolants for refrigerators and air conditioners, in foams, sovents, and aerosol spray cans.
In 1987, all industrial nations agreed to cut their use of CFCs in an agreement known as the Montreal Protocol. Even if all ozone-depleting chemicals are phased out, it could take a century for conditions in the atmosphere to return to what they were in the 1980s.
Since the Industrial Revolution and the subsequent massive burning of fossil fuels - coal, oil, and natural gas - scientists have detected much more carbon dioxide in the atmosphere. This could cause the temperature to rise by an additional one to three degrees Celsius by the year 2050.
Scientists agree that the increased number of heat waves and the rising incidence of violent storms are linked to global warming.
Above average temperatures in polar regions are melting glaciers, and sea levels are rising as a result.
Other effects cannot be directly linked:
- extended ranges for diseases
- earlier arrival of spring
- shifting plant and animal ranges
- bleaching of coral reefs
In 1997, Canada was among the countries that agreed to sign the Kyoto Protocol, promising to reduce greenhouse gas emissions by 6 per cent of our 1990 level by 2012.
There are many sources of energy that could be used to lessen dependence on fossil fuels. These include wind turbines, solar power panels, tidal power, ground source energy or geothermal power, which uses heat from underground sources where available.
Can Canada make a difference? Canadians consume over forty times as much energy as people in developing countries, and our high standard of living means we consume resources at a much higher rate. Our small population can have as much impact on world energy and resources as a less developed country many times our size.
Watch "The 11th Hour"
Agriculture and Soil
Soil is the basis of the biosphere and provides survival for plant and animal life. The formation of soil is a slow process, taking hundreds of years in some places. The removal of soil by wind or water erosion can take place in a fraction of that time.
Soils are being lost or degraded around the world.
Many areas of the world are subject to desertification - land turning to desert.
In the area south of the Sahara in Africa, the area called the Sahel experienced years of drought in the 1970s. Cattle, the people's main livelihood, overgrazed the sparse grasses that held the soil. Desperate people gathered what firewood was available. Gradually the desert spread.
In North America, the lessons of the "dust bowl" of the 1930s led to improved farming techniques. Farmers planted trees to form wind breaks, adopted contour ploughing, and used wheat stubble and straw left after harvesting to return nutrients to the soil and help stop wind erosion.
Poor farming techniques in marginal areas are another problem around the world. Irrigation in many arid areas has made soil too salty to grow crops. Most soils in tropical countries are nutrient poor. If the vegetation is removed, as in the Amazon rainforest, the nutrients quickly disappear and cannot be replaced. Soil on slopes is washed away. The land can become a desert.
The increasing use, in developed and developing countries, of pesticides and herbicides to control insects that attack crops and to kill weeds leads to toxic soil and residues in foods.
Agricultural chemicals can be dangerous, as they eventually seep into groundwater and streams. They can also harm agricultural workers who are in contact with plants that have been sprayed.
The World Wildlife Fund has profiled insects that are needed in agriculture but are being inadvertently poisoned by pesticides. These include ladybugs, honeybees, and dung beetles.
Genetically modified (GM) plants are altered by splicing a gene from another organism into them. Some of these altered plants are more resistant to diseases or pests. Farmers claim that GM crops cost less because they require fewer pesticides and herbicides.
Those in favour of GM crops claim they are little different from regular crops, and that in any case, people have been altering plants by breeding for generations. They point to careful testing by companies and assessment by government agencies before GMOs are approved for use.
Those opposed to GM crops are concerned about the lack of long-term testing, and also about the possibility of GM crops cross-breeding with other crops. They claim that in less developed countries, use of GM seed will make farmers reliant on multinational seed companies and eventually add to their costs of production.
Almost half of the forests that covered the earth before humans began to practice agriculture have been cleared or reduced to a degraded state.
The rate at which the world's tropical rainforests are being destroyed has become a major issue for those concerned with sustainability.
These forests are storehouses of biodiversity, or the variety of life on earth.
As well, tropical rainforests absorb carbon dioxide from the atmosphere and give off oxygen. This is why deforestation is a cause of global warming.
In Brazil, poor people are being encouraged to move into the forests and clear land to use for farming. Huge cattle ranches have been set up. Building roads to gain access to oil and mineral resources has opened up forested lands to settlement. Loggers make huge profits from hardwood timber.
The effects of forest clearance are far ranging. Most tropical soils are infertile; once the forest cover is removed, the few nutrients are used up, and wind and rains can erode the soil. What remains is an arid wasteland that is sometimes used for limited cattle grazing.
Damage is particularly severe on hillsides. Soil erosion leads to the silting of lakes and rivers, and clogs up hydro dams. Floods are more common, as the forests are no longer there to absorb the rainfall and release it slowly.
The temperate and northern forests make up approximately 20% of the Earth's land cover. Canada has one-quarter of the world's temperate coastal forest, one-third of the world's boreal (northern) coniferous forest, and virtually all of the world's old growth red and white pine. These forests are used principally for logging and recreation.
Canada's forests stretch from the Pacific coast to the Atlantic. They include one of the world's largest assortments of lakes and wetlands, and are home to over 100,000 species of plants and animals. They provide over $70 billion worth of value to the economy.
Wildlife extinction will be one of the consequences of the decline of boreal forests. Canada is home to one-third of the world's wolf population and brown and black bears, and more than half the world's barren-ground caribou. Ensuring the survival of these species means preserving their habitats.
These forests are threatened by industrial development, acid precipitation, and climate change.
Once considered only a source of revenue, they are now seen as a resource with many uses: recreation, research, industry, and - in the case of First Nations - culture.
These diverse needs must be balanced with the principles of good stewardship. Stewardship implies careful management of resources so they are sustainable.
Conserving paper and packaging can play a major role in the preservation of forests. Global paper use has grown 600 per cent since 1950.
Ecotourism: Problem or Solution?
One Step Forward, One Step Back?
Since the 1992 Earth Summit in Rio de Janeiro, Canada has attempted to make its economy more responsive to environmental concerns:
- forest practices have improved significantly
- waste recycling has been adopted by many communities
- turning sewage into fertilizer
- more energy efficient cars and buildings
We've been less successful in reducing the use of pesticides and herbicides, and in cutting down on packaging and paper consumption.
The rate of depletion of Canada's boreal forests, groundwater supplies, and other resources continues to be a concern if sustainability is to be achieved. Greenhouse gas emissions have increased, despite our agreement to reduce them.
A square meter of a South African public park over 24 hours.
Iowa cornfield over 2 nights and 3 days.
Prof. Nakul Singh Chauhan