What is Environmental Sustainability?
An unofficial definition is "the degree to which our surroundings
can be maintained in a certain state or at a proper standard". In this
context the environment should be thought of as the whole planet and its atmosphere,
rather than just the local surroundings.
From a human perspective the environment ought
to be healthy, comfortable, productive and pleasant to live in - I assume many other
species would have similar "wishes" if they could express them! Many factors
influence this - including pollution, land quality and productivity, climate, bio-diversity
and availability of natural resources.
Some of the many examples of unsustainable practices can be seen in the food industry.
The demand for increasing company profits, and understandable consumer demand for
cheap food, has contributed to loss of wildlife habitat and the increasing use of
inorganic fertilizer, pesticides and herbicides. Hence questions are asked such as
"where have all the wild birds gone?".
In part mitigation, gardens and public areas could
be maintained to provide a better wildlife habitat, at least in border or less used
areas. These areas may then become more interesting for us as well as wildlife.
Areas of lawn could be left in rotation - here a butterfly (ringed) is hovering
around the mixed clover and cat's ear (yes it is - honestly!)
This is a useful indicator of environmental sustainability - it is the area of
land a person needs to provide all their resources and to absorb waste and emissions
that they produce (including home, vehicles etc.). Many developed countries have average
per person Ecological Footprints that are far too high, which is resulting in degradation
of the environment at an alarming rate. This degradation is made even worse by poor
countries which understandably want to develop, but are doing so in a non-sustainable
way. The table below shows the Ecological Footprint per person (in hectares) for some
contrasting countries - source "Redefining Progress" www.rprogress.org (2001).
per person (ha)
* According to these figures in 2001 we needed 1.3 earths to support
the worlds population in a sustainable way (obviously a value greater than 1 is not
sustainable!). Estimate your own Ecological
Footprint (opens in new window) [ed. note 5/2016: I see that this is now a subscription
service, other free websites may be available].
The Greenhouse Effect
This natural effect causes the
earth's average temperature to be about 35C warmer than it would otherwise be, so
it's generally a very useful thing! The effect is caused by "greenhouse"
gases in the atmosphere absorbing heat which is radiated from the earth, and radiating
much of it back - effectively acting as a blanket. The main gases which perform this
function are CO2, water vapour, methane, nitrous oxide
and CFCs - see summary of green house gases
The concentration of greenhouse gases in the atmosphere has been increasing
since the Industrial Revolution, and more rapidly in recent decades. It is generally
believed that this is causing the earth's average surface temperature to increase
steadily, and is additional to naturally occurring climatic cycles. The projected
effects of "enhanced global warming" due to human activity have been extensively
Most species adapt and migrate according to climatic conditions. However,
many won't be able to cope with the current rapid increase in mean temperatures because
they cannot migrate fast enough towards the Polar regions (and Polar species have
nowhere to go). For those that can migrate (e.g. humans) competition for reducing
amounts of space and resources in temperate regions is likely to increase.
In the case of electricity generation, fossil
fuel based generation uses up the world's limited supply of these resources, contributing
significantly to the worlds CO2 emissions (around 30%
of UK CO2 emissions). Natural gas fired generation
is cleaner and produces less CO2, but supply is limited
and uncertain. Generating technologies which convert different forms of solar energy
into electricity are much more environmentally friendly. These include wind, tide,
and photovoltaic cells - and apart from their construction consume no resources and
produce no CO2 emissions. Hydro-electric generating
systems have the same advantages, but large dam schemes can have serious negative
environmental impacts. As for nuclear power ........ I'm not getting into that.
For transport, fuel cell power has been the dream for a long
time (or a nightmare for oil company executives). There is no greenhouse gas emission
when developing power (only water is emitted), but the environmental cost of manufacturing
the units has to be considered. The hydrogen fuel needs to be produced using renewable
(solar derived) energy - using fossil fuelled energy for this purpose would render
the exercise pointless from an environmental viewpoint. Since hydrogen and oxygen
are explosive, safe storage is problematic.
In agriculture technology already exists to control the amount
of inorganic fertilizer applied to fields so that just enough for a particular crop
is used. Wider usage of such technology should lessen manufacturing impacts and harmful
effects of over application of fertilizers. In areas which already have excess nutrients,
the establishment of strips of fast growing plants or trees along water courses will
absorb some of the excess. The biomass produced can be put to good use, possibly as
a type of fuel.
Clean(er) technologies can take a long time to develop, and thus become economically
viable for replacing old polluting technologies. It could be several more decades
until fuel cell powered vehicles are the norm, and no replacement for aero engines
is on the horizon. However, immediate curbs on environmental degradation and emission
of greenhouse gases are required. People in developed countries can begin to improve
environmental sustainability immediately if we make modifications to our behaviour.
Rich countries, supported by global initiatives, could assist poor countries to
develop in an environmentally sustainable way. This means providing financial assistance
and training so that sustainable power generation (for example solar/photovoltaic
based), and appropriate industrial and agricultural practices can be encouraged. It
is believed that economic development promotes population stabilisation, as evidenced
in developed countries - this has the potential of reducing demands on the environment
in the long term.