J-zine - Hot or Cold?

Hot or Cold?

Greenhouse Gases
Carbon Dioxide (CO₂) is the result of burning organic material. It has a moderate greenhouse effect. Living creatures produce CO₂. It is a natural constituent of air, but is on the increase. Without CO₂, plants would die and we would freeze to death; with too much, we will all roast.
Methane (CH₄) is produced by certain types bacteria-like organisms (the so called methanogens) that thrive in places with little or no oxygen -- swamps, rubbish tips and the gut of a variety of animals from termites to cattle. Oil and natural gas reservoirs contain vast amounts of methane. Methane has a strong greenhouse effect, but is gradually transformed into CO₂.
Fluorocarbons (CH_nX_m) are better known for their adverse effects on the ozone layer, but they are also potent greenhouse Gases. Fluorocarbons are very stable and break down very slowly. Some have lifetimes of hundreds of years.

Recently, delegates from no less than 160 countries met again to decide what to do about emissions. There is serious concern that the average global temperature is rising and that the cause is what are called greenhouse gas emissions (See table on the right). The gradual rise in CO₂ in the atmosphere has been linked to the industrial revolution. Quite simply, we started burning larger and larger quantities of fossil fuels (coal, oil and natural gas). More CO₂ was produced. At the same time, we were chopping down forests that use sun light to convert CO₂ back into oxygen. We had disturbed Nature's balance. More CO₂ in the atmosphere means more of the sun's heat is retained. Slowly the temperature will rise.

In fact, the situation is much more complex than that. Several other factors may also play a part. During the middle ages, Europe experience a period of unusually cold Winters. This Little Ice Age has been linked to to the equally unusual lack of sun spots. The actual connection between sun spots and climate is not understood. Was the sun cooler? No, probably not; at least not enough to matter. More likely the cooling down was connected to other factors, such as the sun's magnetic fields. The current global warming may, in part, be due to changes in the sun.

Most emphasis is placed on CO₂ emissions, but the massive destruction of forest and jungle areas is possibly equally important. Another important factor is methane (CH₄) emissions. Enormous quantities have been released as a result of oil production. Methane is also produced naturally in swamp lands. If the tundra areas of Asia warm, this methane production could increase enormously. Cattle and other ruminants are another source of methane gas. The bacteria that digest their food produce large quantities of methane gas. Exactly how important cattle flatulence is in in global warming is unclear. Methane is a tiny constituent of air, but it has a stronger greenhouse effect than CO₂.

Another matter is that the global climate has been uncommonly warm these last few thousand years. In a recent report published in the magazine, Nature, Dr Jess Adkins of the Massachusetts Institute of Technology, pointed out that the present warm period - the Holocene - has been stable for around 9,000 years. Given that the last warm inter-glacial period was also about 9,000 years long, he concludes that the time may be ripe for another ice age. "The global climate system seems to be poised at one of these thresholds," he said. The man-made global warming may disturb this. The authors of the Nature report say it is difficult to estimate how these emissions will influence the recurring pattern of ice ages.

The transition from the warm inter-glacial climate we enjoy now to a new ice-age would be very short -- in geological terms, almost instantaneous (as little as one or two hundred years). Very little is known about it because of its brevity. It is almost as if a switch is thrown over into another position. The deep warm-water transport called the Atlantic Elevator, stops. Ice starts to cover the Northerly land masses and the ice reflects back sun light causing further cooling. The El Niño - Southern Oscillator climate system would presumably also be affected. As would be the Asian monsoons.

If we are currently worried about global warming, then we don't have to worry about an Ice-age, right? Wrong. Past records, skimpy as they are, can be read to support the following scenario. Global warming, slow at first will increase in speed. Some vegetation will flourish, but much will die. Decaying or burning vegetation generates CO₂. The faster the CO₂ level increases, the faster the temperature increase, until we reach a peak. At that point, the temperature could crash catastrophically and the next Ice-age will have started.

Ants and Intelligence