Dear Editor,
In my readings on global warming and climate change on the Internet and from other sources, I have encountered conflicting claims being made by scientists in the field. Some claims, which go against the consensus, seem to make sense to me, but as I am only a reasonably informed layman in the field and not an expert, I proffer some of the claims for more informed persons to comment on.
First, it is the consensus among climatologists that global warming is happening, that it is being induced mainly by human activities, and that it is causing climate change and rising ocean levels. I omit all the technical details. This consensus has led to international policies among the developed countries that will, in effect, hinder the development of developing/ under-developed nations.
On the other hand, there is a minority of scientists who claim that global warming is due mainly to the Earth entering the upswing of an interglacial period between Ice Ages. This, they believe, is being induced by natural perturbations in the Earth’s orbit around the Sun, wobbles of the Earth’s rotation around its axis, solar flares from the Sun, geothermal effects and other as yet unknown factors beyond human influence. They believe that human activities have not contributed significantly to global warming, and that instead of futilely battling the inevitable, humankind must prepare for radical changes so as to ensure its survival. Some even believe global warming is not happening.
Second, it is the scientific consensus that tropical rainforests are significant absorbers of carbon dioxide (CO2), the chief greenhouse gas, and vital emitters of oxygen (O2), the gas needed for respiration, and as such all remaining rainforests must be preserved and also reforested. They refer to tropical rainforests as carbon sinks where CO2 is absorbed and sequestered as carbon in vegetation for years to come. The trouble is that most rainforests are found in developing/under-developed nations, who maintain that they must utilize their rainforest resources to power their development.
However, in recent years, a few researchers have claimed that tropical rainforests are not the carbon sinks they are thought to be and that net CO2 emissions from rain forests may be contributing to global warming. Let me elaborate. As anyone who has done some basic botany knows, green plants respire all the time, but they photosynthesize only during daylight. During respiration, plants absorb O2 and release CO2, using up sugar. In photosynthesis, plants absorb CO2 and release O2, producing sugar. If plants absorb as much CO2 as they release and release as much O2 as they absorb, then they are CO2 neutral and O2 neutral, that is, there is no net release or net absorption of the gases. For plants to be net O2 producers and net CO2 absorbers they must convert some of the sugar into biomass rather than using it all in respiration. This means that such plants must be growing and getting heavier. This much is true. Here is where the controversy begins and where I need help.
The minority of researchers claim that not only the trees in a rainforest must be accounted for, but also the rivers, streams, flooded areas and most importantly, decaying vegetation, which emit excess CO2 during decomposition. They claim to have found that the amount of CO2 given off in these areas is three times that of some current estimates, and that traditional measurements are underestimating the amount of CO2 in the air around tropical forests. They say that that the amount of CO2 is about even, with as much being released as being absorbed by the forests. (http://www.bio.net/bionet/mm/ag-forst/2002-April/017088.html).
Another claim they make is that relatively minor weather variations – particularly increases in temperature – could turn the forests into major net emitters of CO2. They reason that as the world continues to warm, tropical rain forests could shrivel, perhaps so much that they turn into grasslands with scattered trees. As trees die and decay, they release more CO2 through decomposition and more prevalent forest fires. (http://www.climateark.org/shared/reader/welcome.aspx?linkID=61405)
Third, (and this not a cry of the minority, but an inconvenient truth not well-publicized), there are other known greenhouse gases such as water vapour, methane, nitrous oxide, hydroflurorcarbons, and the recently identified synthetic compound called trifluoromethyl sulfur pentafluoride. Although it is extremely rare in the atmosphere, concentrations of this gas are rising quickly. This gas is a more effective heat trap than all other known greenhouse gases and scientists have been unable to confirm its industrial source. It is also believed that prodigious quantities of methane, a heat insulator 20 times more effective than CO2, are trapped in the permafrost of the tundra regions. As the permafrost melts due to global warming, the methane will be released to contribute its bit to global warming. What is certainly known – from direct measurements and estimates – is that humankind dumps over 26 billion tons of CO2 (one-fifth of that from the USA alone) into the atmosphere every year, and that’s over 1 % of the total atmospheric CO2. How much of this is reabsorbed by green plants, the oceans and soils is not known and is anybody’s guesstimate based on their assumptions and calculations. Preserving our rainforests in exchange for carbon credits and hard cash might not be such a bad deal after all.
I remember reading or hearing somewhere a few years ago (I can’t retrieve the source) that if the people of China (pop. 1.3 billion) were to achieve the fossil fuel powered, electric toothbrush living standards of the USA (pop. 0.3 billion), within 50 years the Earth will be devoid of all oxygen-breathing life. (You don’t need the source; the arithmetic proves the statement correct.) Include India (pop. 1.1 billion) and Africa (pop 0.8 billion) and anyone can see we are in for a torrid time. In spite of the spectre of Hiroshima, Nagasaki, Three Mile Island and Chernobyl, humankind’s only salvation might be to go nuclear. Hung Fat Choy: “Happy New Year.”
Yours faithfully,
M. Xiu Quan-Balgobind-Hackett
