Human Impact
Not surprisingly, the impact of this population growth on the environment since 1750 been extensive. Now, not a day goes by but we hear of droughts, floods, famines, wars over resources, extinctions, and in the last 20 years, the increasingly evident effects of global warming. This
impact has been expressed in what has become known as the Commoner-Ehrlich Equation:
I = P x A x T.
This states that the
impact (
I) on the environment is directly proportional to the population size
(P), the
‘affluence’ (A) {defined as the resources a population consumes and wastes} and
technology (T) through which we (1) prolong life, (2) produce things more quickly and cheaply (feeds back into consumerism and affluence) and (3) grow food faster – which feeds back into „population‟. All-in-all, this equation neatly summarises the impact of humankind on the planet.
The reality of the impact has already been mentioned: deforestation, soil erosion, salinity of the soil, waste disposal to landfill, desertification, declining fish stocks, global warming and rising sea levels and climate change. Politicians, unsure what to do, offer solutions which include suggestions such as: develop fuel efficient cars; change to efficient light bulbs; fly less; build renewable energy and nuclear power plant; increase mass transit systems; plant trees etc., etc. These solutions only address the reduction of the
Affluence and
Technology terms, but never the
Population term.
Reducing impact by decreasing affluence only partly addresses the problem since populations are growing faster than affluence decreases – vide Africa, India and the Philippines. Technology does not decrease. Whilst it can be used to reduce the impact of
affluence, it is likely that its benefits in energy saving devices will be cancelled by its disadvantages, as businesses continue to use it to maximise their economic growth via consumerism. So, realistically,
impact will continue to rise since economic growth demands it. This is bad news since, as we will now see, human impact on the planet is already unsustainable.
Few would argue with the statement that „
population cannot continue to increase indefinitely‟. But this begs the question: "
Have we exceeded the limit?" This question demands a reply to:
"How do we define the limit?" A reasonable answer, I suggest, is:
"The limit of population at any given time is determined by the planet‟s ability to support that population‟s impact indefinitely." So: "
Is the current population sustainable?" To throw some light on this, we need to use a tool called
Ecological Footprinting developed in the 1990s by William Rees and Mathis Wackernagel. It is now managed by the Global Footprinting Network (GFN) and publishes annually the ecological parameters for every country in the Living Planet Reports of the World Wildlife Fund (WWF). The latest of these reports appeared in 2006 and gives footprinting statistics for 2003. What follows is based on data taken from that report.
Ecological Footprinting
Biocapacity
Ecological Footprinting measures the impact of humans population on the planet. It first measures how much resource the planet generates in a year and then calculates how much we use: a biological income - expenditure account. On the income side, the total biological product over a year is called the planet‟s
total biocapacity and is defined as the biologically productive area of land and water arising from forests, croplands, grazing lands and fishing grounds needed to:
a) produce sustainably all the biomass we use and
b) absorb all the waste we produce, including CO2 emissions
Total biocapacity is measured in
global hectares - defined as the total biocapacity divided by the total physical area generating it
. In 2003, the earth‟s total biocapacity was 11.2 billion gha (Ggha). However, a more useful measure is the
biocapacity per head of population in units of
global hectares per capita (gha/cap). Called simply the
biocapacity, it describes the
average land area available to sustain each person. In 2003, since there was a population of 6.3 billion humans sharing the earth‟s 11.2 Ggha, the biocapacity was 1.78 global hectares per person.
Rest of equation and data here
http://www.populationmatters.org/documents/sustainable_populations.pdf
But the answer in rough figures lies in the conclusion
Concluding Remarks and Observations
The Global Network Footprint statistics show that,
globally, we left sustainability behind during the late 1980s. Since then, increasing world affluence and populations have driven us
deeper into unsustainable territory. The carbon dioxide emissions of each country pollute the atmosphere for every other nation and the human urge to improve its affluence, or impact through Technology – no matter how well off it already is – is a driver that seems set to continue. It follows that if affluence and technology are not able to decrease, then the only parameter left to reduce is
population. The ecological footprinting data analysed in this paper have given guidelines; a sustainable global population is around
two to three billion people; for the UK, the figure is between 17 and 27 million.
http://www.populationmatters.org/documents/sustainability_populations.pdf
