Peak population and dieback
"Dieback" or "dieoff" of the human population is one of
those taboo subjects which you never hear politicians talk
about as there are no votes in it. But it is
important that we discuss it and form some ideas about what it
is, what causes it, how likely it is to occur and what we
should do about it.
The fundamental underlying concept is that there is a
maximum human population which an ecosystem can carry
sustainably. The ecosystem in question can be a local
ecosystem, such as Easter Island or the formerly Mayan
inhabited region of Central America, both of which experienced
profound dieback as a result of environmental
degradation. Alternatively, it can be the entire
planet.
At the beginning of the industrial revolution (around 1800)
the global human population was around 1 billion, and these
people were on the whole living sustainably and using only
small amounts of non-renewable resources. Today, the
human population is around 6.7 billion and we are using very
large amounts of non-renewable resources, in particular oil,
natural gas and fossil water, to produce our
food. A population of 6.7 billion humans may
therefore be an unsustainable number, which can only be
maintained for a relatively short time until the non-renewable
resources are used up. At that point, a correction must
take place and the population must be reduced once again to a
sustainable level.
Let's say, for the sake of argument, that the maximum
sustainable number of humans which the planet can support is 2
billion - twice as many as the number alive at the beginning
of the fossil fuel age. In order to make the necessary
correction, 4.7 billion people would have to disappear, and
this is what is sometimes referred to as "dieback" or
"dieoff". How might this happen?
In earlier, simpler times, a failure of the harvest
resulted in dieback by starvation. There is
archaeological evidence of this happening, for example, on
Easter Island, and it still happens in Third World
countries. In wealthy industrialised countries with more
complex societies, factors other than simple starvation
may play a role. To get some idea what to expect
when a modern industrial society collapses, we can look at the
example of the collapse of the Soviet Union in the early 1990s
and what happened to the population of Russia during this
period.
The population of Russia hit a historic peak at 148,689,000
in 1991, just before the breakup of the Soviet Union, but then
began a decade-long decline, falling at a rate of about 0.5%
per year due to declining birth rates and rising death
rates. The cause of the rising death rates is widely
debated. Very little if any was due to starvation,
mainly because the former state-run bakeries continued to
function and to distribute bread as they had done
pre-collapse. The death rate peaked at around 17 per
1000 in 2003 and the birth rate bottomed out at around 8 per
1000 in 1999, but subsequently both of these indices moved
towards a more normal level of 14 per 1000 per annum as the
Russian economy improved. Alcoholism was a significant
contributing factor, although this had been a pre-existing
trend in the population prior to collapse. Rates of
heart disease in Russia were higher than the European average
both pre and post collapse. The increase in mortality
was from multiple causes. (http://en.wikipedia.org/wiki/Demographics_of_Russia)
A similar increase in all cause mortality has long been
observed in people subjected to psychological stress. A
recent study found that after the loss of a spouse, all cause
mortality increases by 27% per annum (citation
needed).
If psychological stress is a significant
contributing factor to all-cause mortality then the high rates
of psychological stress apparently being experienced by
populations of post-industrial societies are cause for
concern. In 2005 10% of Americans were taking
antidepressants and 16% of Americans were taking
benzodiazepines. The levels today are probably
higher. The reasons for these widespread high levels of
psychological discomfort are unclear but may be related to
societal factors such as fast-paced lifestyles, insecurity of
employment and fragmented families and communities.
A shortage of fossil fuels may result
in an enforced simplification of life (less commuting to work,
more tending vegetable gardens) which in the long term may
reduce psychological stress. However, in the short term
many people will experience a profound increase in
psychological stress because they are unprepared for the
changes being forced upon them. An increase in all cause
mortality may follow.
Diabetes is another factor which
may increase mortality in the coming decades. The
current epidemic of type 2 diabetes is largely an unintended
consequence of our fossil fuel dependency, as a result of
which there have been simultaneous increases in the
availability of high fat food and personal transportation,
resulting in people eating more, exercising less and becoming
obese. As a rough estimate, if the onset of
diabetes occurs some 10-20 years after the onset of
obesity, and the onset of complications of diabetes
(renal failure, blindness, gangrene of extremities) occurs
some 10-20 years after the onset of diabetes, and "peak
obesity" is likely to coincide with peak oil, then that
puts "peak diabetic complications" about 30 years from
now. Couple that with a possible decreased availability
of medical care due to oil shortages and economic recession,
and one can reasonably expect that in 30 years from now
diabetics may be even more numerous than they are today, and
their life expectancy may be shorter.
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