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| The Earth Day flag
includes a NASA Blue Marble photo. |
Sustainability
Sustainability means that a process or state can be
maintained at a certain level for as long as is wanted.
The study of ecology believes that sustainability is
achieved through the balance of species and the
resources within their environment. To maintain this
equilibrium, available resources must not be depleted
faster than resources are naturally generated.
Healthy ecosystems and environments are necessary to the
survival of humans and other organisms. Ways of reducing
negative human impact are environmentally-friendly
chemical engineering, environmental resources management
and environmental protection. Information is gained from
green computing, green chemistry, earth science,
environmental science and conservation biology.
Ecological economics studies the fields of academic
research that aim to address human economies and natural
ecosystems.
Ways of living more sustainably can take many forms from
reorganizing living conditions (e.g., ecovillages,
eco-municipalities and sustainable cities), reappraising
economic sectors (permaculture, green building,
sustainable agriculture), or work practices (sustainable
architecture), using science to develop new technologies
(green technologies, renewable energy and sustainable
fission and fusion power), or designing systems in a
flexible and reversible manner, and adjusting individual
lifestyles that conserve natural resources.
Despite the increased popularity of the use of the term
"sustainability", the possibility that human societies
will achieve environmental sustainability has been, and
continues to be, questioned—in light of environmental
degradation, climate change, overconsumption, population
growth and societies' pursuit of unlimited economic
growth in a closed system. |
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Environmental dimension
Healthy ecosystems provide vital goods and services to
humans and other organisms. There are two major ways of
reducing negative human impact and enhancing ecosystem
services and the first of these is environmental
management. This direct approach is based largely on
information gained from earth science, environmental
science and conservation biology.
Environmental management
At the global scale and in the broadest sense
environmental management involves the oceans, freshwater
systems, land and atmosphere, it can also be equally
applied to any ecosystem from a tropical rainforest to a
home garden.
Atmosphere
Management of the global atmosphere now involves
assessment of all aspects of the carbon cycle to
identify opportunities to address human-induced climate
change and this has become a major focus of scientific
research because of the potential catastrophic effects
on biodiversity and human communities.
Other human impacts on the atmosphere include the air
pollution in cities, the pollutants including toxic
chemicals like nitrogen oxides, sulfur oxides, volatile
organic compounds and particulate matter that produce
photochemical smog and acid rain, and the
chlorofluorocarbons that degrade the ozone layer.
Freshwater and oceans
Water covers 71% of the Earth's surface. Of this, 97.5%
is the salty water of the oceans and only 2.5%
freshwater, most of which is locked up in the Antarctic
ice sheet. The remaining freshwater is found in
glaciers, lakes, rivers, wetlands, the soil, aquifers
and atmosphere. Due to the water cycle, fresh water
supply is continually replenished by precipitation,
however there is still a limited amount necessitating
management of this resource.
Awareness of the global importance of preserving water
for ecosystem services has only recently emerged as,
during the 20th century, more than half the world’s
wetlands have been lost along with their valuable
environmental services. Increasing urbanization pollutes
clean water supplies and much of the world still does
not have access to clean, safe water. Greater emphasis
is now being placed on the improved management of blue
(harvestable) and green (soil water available for plant
use) water, and this applies at all scales of water
management.
Ocean circulation patterns have a strong influence on
climate and weather and, in turn, the food supply of
both humans and other organisms. Scientists have warned
of the possibility, under the influence of climate
change, of a sudden alteration in circulation patterns
of ocean currents that could drastically alter the
climate in some regions of the globe. Ten per cent of
the world's population – about 600 million people – live
in low-lying areas vulnerable to sea level rise.
Land use
Loss of biodiversity stems largely from the habitat
loss. Land use change is fundamental to the operations
of the biosphere because alterations in the relative
proportions of land dedicated to urbanisation,
agriculture, forest, woodland, grassland and pasture
have a marked effect on the global water, carbon and
nitrogen biogeochemical cycles and this can impact
negatively on both natural and human systems. At the
local human scale, major sustainability benefits accrue
from sustainable parks and gardens and green cities.
Food is essential to life. Feeding more than six billion
human bodies takes a heavy toll on the Earth’s
resources. Environmental problems associated with
industrial agriculture and agribusiness are now being
addressed through such movements as sustainable
agriculture, organic farming and more sustainable
business practices. |
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Management of human
consumption
The underlying driver of direct human impacts on the
environment is human consumption. This impact is reduced
by not only consuming less but by also making the full
cycle of production, use and disposal more sustainable.
Key resource categories relating to human needs are
food, energy, materials and water. |
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| Flow of CO2 in an
ecosystem. |
Energy
The Sun's energy, stored by plants (primary producers)
during photosynthesis, passes through the food chain to
other organisms to ultimately power all living
processes.
Since the industrial revolution the concentrated energy
of the Sun stored in fossilized plants as fossil fuels
has been a major driver of technology which, in turn,
has been the source of both economic and political
power. In 2007 climate scientists of the IPCC concluded
that there was at least a 90% probability that
atmospheric increase in CO2 was human-induced, mostly as
a result of fossil fuel emissions but, to a lesser
extent from changes in land use. Stabilizing the world’s
climate will require high-income countries to reduce
their emissions by 60–90%.
Reducing greenhouse emissions, is being tackled at all
scales, ranging from tracking the passage of carbon
through the carbon cycle to the commercialization of
renewable energy, developing less carbon-hungry
technology and transport systems and attempts by
individuals to lead carbon neutral lifestyles by
monitoring the fossil fuel use embodied in all the goods
and services they use. |
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| Irrigation, dams and
industry can affect the water cycle. |
Water
Water security and food security are inextricably
linked. In the decade 1951–60 human water withdrawals
were four times greater than the previous decade. This
rapid increase resulted from scientific and
technological developments impacting through the economy
– especially the increase in irrigated land, growth in
industrial and power sectors, and intensive dam
construction on all continents. This altered the water
cycle of rivers and lakes, affected their water quality
and had a significant impact on the global water cycle.
Currently towards 35% of human water use is
unsustainable, drawing on diminishing aquifers and
reducing the flows of major rivers: this percentage is
likely to increase if climate change impacts become more
severe, populations increase, aquifers become
progressively depleted and supplies become polluted and
unsanitary.
Water efficiency is being improved on a global scale by
increased demand management, improved infrastructure,
improved water productivity of agriculture, minimising
the water intensity (embodied water) of goods and
services, addressing shortages in the non-industrialised
world, concentrating food production in areas of high
productivity, and planning for climate change. At the
local level, people are becoming more self-sufficient by
harvesting rainwater and reducing use of mains water. |
Food
The American Public Health Association (APHA) defines a
"sustainable food system" as "one that provides healthy
food to meet current food needs while maintaining
healthy ecosystems that can also provide food for
generations to come with minimal negative impact to the
environment. A sustainable food system also encourages
local production and distribution infrastructures and
makes nutritious food available, accessible, and
affordable to all. Further, it is humane and just,
protecting farmers and other workers, consumers, and
communities."
Concerns about the environmental impacts of agribusiness
and the stark contrast between the obesity problems of
the Western world and the poverty and food insecurity of
the developing world have generated a strong movement
towards healthy, sustainable eating as a major component
of overall ethical consumerism. The environmental
effects of different dietary patterns depend on many
factors, including the proportion of animal and plant
foods consumed and the method of food production.
A Mediterranean diet is recommended which is associated
with health and longevity and is low in meat, rich in
fruits and vegetables, low in added sugar and limited
salt, and low in saturated fatty acids; the traditional
source of fat in the Mediterranean is olive oil, rich in
monounsaturated fat. The healthy rice-based Japanese
diet is also high in carbohydrates and low in fat. Both
diets are low in meat and saturated fats and high in
legumes and other vegetables; they are associated with a
low incidence of ailments and low environmental impact.
At the global level the environmental impact of
agribusiness is being addressed through sustainable
agriculture and organic farming. At the local level
there are various movements working towards local food
production, more productive use of urban wastelands and
domestic gardens including permaculture, urban
horticulture, local food, slow food, sustainable
gardening, and organic gardening.
Sustainable seafood is seafood from either fished or
farmed sources that can maintain or increase production
in the future without jeopardizing the ecosystems from
which it was acquired. The sustainable seafood movement
has gained momentum as more people become aware about
both overfishing and environmentally-destructive fishing
methods.
Materials, toxic substances,
waste
As global population and affluence has increased, so has
the use of various materials increased in volume,
diversity and distance transported. Included here are
raw materials, minerals, synthetic chemicals (including
hazardous substances), manufactured products, food,
living organisms and waste. By 2050, humanity could
consume an estimated 140 billion tons of minerals, ores,
fossil fuels and biomass per year (three times its
current amount) unless the economic growth rate is
decoupled from the rate of natural resource consumption.
Developed countries' citizens consume an average of 16
tons of those four key resources per capita (ranging up
to 40 or more tons per person in some developed
countries with resource consumption levels far beyond
what is likely sustainable.
Sustainable use of materials has targeted the idea of
dematerialization, converting the linear path of
materials (extraction, use, disposal in landfill) to a
circular material flow that reuses materials as much as
possible, much like the cycling and reuse of waste in
nature. This approach is supported by product
stewardship and the increasing use of material flow
analysis at all levels, especially individual countries
and the global economy. The use of sustainable
biomaterials that come from renewable sources and that
can be recycled is preferred to the use on non-renewables
from a life cycle standpoint.
Synthetic chemical production has escalated following
the stimulus it received during the second World War.
Chemical production includes everything from herbicides,
pesticides and fertilizers to domestic chemicals and
hazardous substances. Apart from the build-up of
greenhouse gas emissions in the atmosphere, chemicals of
particular concern include: heavy metals, nuclear waste,
chlorofluorocarbons, persistent organic pollutants and
all harmful chemicals capable of bioaccumulation.
Although most synthetic chemicals are harmless there
needs to be rigorous testing of new chemicals, in all
countries, for adverse environmental and health effects.
International legislation has been established to deal
with the global distribution and management of dangerous
goods.
Every economic activity produces material that can be
classified as waste. To reduce waste industry, business
and government are now mimicking nature by turning the
waste produced by industrial metabolism into resource.
Dematerialization is being encouraged through the ideas
of industrial ecology, ecodesign and ecolabelling. In
addition to the well-established “reduce, reuse and
recycle,” shoppers are using their purchasing power for
ethical consumerism. |
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