26/09/2006 | by Onboard
Red-neck Fun With The Planetary Life Support System
“The sun, the moon and the stars would have disappeared long ago… had they happened to be within the reach of predatory human hands.” – Havelock Ellis, The Dance of Life, 1923
“Because we don’t think about future generations, they will never forget us.” – Henrik Tikkanen
A Crude Metaphor
Imagine, if you will, our planet as a great glass sphere full of chemicals. Underneath, there is a large Bunsen burner with a flame regulated by an attached thermostat. Over time, the sphere gradually heats up and cools down according to the control of the thermostat. As this occurs, the chemicals, chemical compositions, and chemical reactions change accordingly.
Now suppose a naughty and not very bright student (possibly from Texas) breaks into the laboratory and, just for a laugh, breaks the thermostat and cranks the burner up to maximum flame.
What do you suppose would happen?
An Even Cruder Reality
Carbon dioxide is one of the products of respiration. It is also a necessary reactant in the photosynthesis of plant tissue. As long as respiration and photosynthesis remain balanced (known as the carbon cycle) then all is right with the world. Unfortunately, with increased industrialisation and the rapid destruction of the world’s forests, the levels of carbon dioxide are rising.
Analysis of ice cores drilled from the Antarctic show the CO2 level fluctuating over the last 500,000 years between about 200 parts per million (ppm) during ice ages to more like 270ppm in warmer inter-glacial periods. Before the start of the Industrial Revolution about 200 years ago, the level of CO2 in the atmosphere was around 270-280ppm. It reached 360ppm in the 1990s and recently climbed to a high of 379ppm. The year-on-year average rise is currently 2ppm.
Almost everyone these days is aware (apart from naughty Texas schoolboys), carbon dioxide is a ‘greenhouse’ gas. The ‘greenhouse effect’ refers to the role played by the layer of gases that effectively trap the heat from the sun in the Earth’s atmosphere. Without them, the planet would be too cold to sustain life as we know it.
Each compound in the greenhouse layer has a distinct capacity for warming and a distinct chemical half-life, or the time a typical molecule spends in the atmosphere before reacting and forming a new compound. Many greenhouse substances, including methane and the halogen-containing compounds, contribute many times more pound-for-pound to the greenhouse effect than carbon dioxide. However, the sheer volume of carbon dioxide in the atmosphere compared to these other trace gases means that carbon dioxide is still by far the largest contributor to man-made greenhouse warming. Additionally, while some greenhouse gases have a half-life of several decades, the half-life of carbon dioxide is in the order of a century. Most of the carbon dioxide we release today will still linger in the atmosphere in 2075 and even 2100.
Cause and Effect
Worse still, studies indicate that if current production of carbon from fossil fuels continues unabated, by the end of the century the land and oceans will be less able to take up carbon than they are today, especially as tropical rain forests (among the largest of Earth’s carbon sinks) are destroyed.
Usually by burning.
Which of course releases even more CO2 into the atmosphere.
“If we maintain our current course of fossil fuel emissions or accelerate our emissions, the land and oceans will not be able to slow the rise of carbon dioxide in the atmosphere the way they’re doing now,” said Inez Y. Fung at the University of California, Berkeley, who is director of the Berkeley Atmospheric Sciences Centre. “It’s all about rates. If the rate of fossil fuel emissions is too high, the carbon storage capacity of the land and oceans decreases and climate warming accelerates.”
Naughty Texas schoolboys may not do very well with all this ‘science stuff’.
Currently, the land and oceans absorb about half of the carbon dioxide produced by human activity, most of it resulting from the burning of fossil fuels. However, Fung’s research indicates that the ‘breathing biosphere’ can absorb carbon only so fast. Beyond a certain point, the planet will not be able to keep up with carbon dioxide emissions.
“The reason is very simple,” says Fung. “Plants are happy growing at a certain rate, and though they can accelerate to a certain extent with more CO2, the rate is limited by metabolic reactions in the plant, by water and nutrient availability, and so forth.”
In addition, increasing temperatures and drought frequencies lower plant uptake of CO2 as plants breathe in less to conserve water. Thus it would appear that the negative effects of hot, dry summers negates the benefits of warm, wet springs. Therefore, a warming climate will not necessarily lead to higher CO2 growing-season uptake, even in temperate areas such as North America.
Another worrisome trend is the warming of the permafrost areas of northern Europe and North America. These regions are known to contain large quantities of methane, a potent greenhouse gas, which could also be released as global warming thaws the tundra and leave behind peat bogs.
This release, triggered by the higher atmospheric carbon levels, is be an example of what is called ‘positive feedback’, when warming itself causes a further temperature rise. Scientists say the rate of release is accelerating at 6% a year, which they think means that by 2060 the peat could account for greater carbon emissions than the burning of fossil fuels.
These feedbacks mean that by the end of this century we will have lost a lot of the free buffering that nature provides and reach what is known as a ‘climatic tipping point’ wherein all these bio-chemical transformations arrive at a stage where they become not only inexorable, but permanent.
Adversely effecting all biological life on Earth.
Naughty Texas schoolboys may not do very well with all this ‘science stuff’, but I’m sure there exist plenty of other occupational endeavours to which they can apply their insipid talents.
Like in the oil industry…
Words: AF Keck, Illustration: http://www.mothi.biz