I would like to take this opportunity to digress somewhat and try to place climate change in a philosophical context:
Some physical systems increase disorder, either by decaying or by actively spreading disorder onto other systems. Such vectors we call "Entropic Agents".
Conversely, some physical systems increase order or decrease disorder either in themselves or in their environment. We call these vectors "Negentropic Agents".
Human Beings are Negentropic Agents gone awry. Now, through its excesses, Mankind is slowly being transformed into an Entropic Agent.
Antibiotics, herbicides, insecticides, pollution, deforestation, etc. are all detrimental to the environment and reduce the amount of order in the open system that is Earth.
Nature must balance this shift of allegiance, this deviation from equilibrium, by constraining the number of other Entropic Agents on Earth - or by reducing the numbers of humans.
To achieve the latter (which is the path of least resistance and a typical self-regulatory mechanism), Nature causes humans to begin to internalize and assimilate the Entropy that they themselves generate. This is done through a series of intricate and intertwined mechanisms:
The Malthusian Mechanism - Limited resources lead to wars, famine, diseases and to a decrease in the populace (and, thus, in the number of human Entropic Agents).
The Assimilative Mechanism - Diseases, old and new, and other phenomena yield negative demographic effects directly related to the entropic actions of humans.
Examples: excessive use of antibiotics leads to drug-resistant strains of pathogens, cancer and deteriorating sperm counts are caused by pollution, heart ailments are related to modern Western diet, AIDS, avian flu, SARS, swine flu, and other diseases are a result of hitherto unknown or mutated strains of viruses.
The Cognitive Mechanism - Humans limit their own propagation, using "rational", cognitive arguments, devices, and procedures: abortion, birth control, the pill.
Thus, combining these three mechanisms, nature controls the damage and disorder that Mankind spreads and restores equilibrium to the terrestrial ecosystem.
Both now-discarded Lamarckism (the supposed inheritance of acquired characteristics) and Evolution Theory postulate that function determines form. Natural selection rewards those forms best suited to carry out the function of survival ("survival of the fittest") in each and every habitat (through the mechanism of adaptive radiation).
But whose survival is natural selection concerned with? Is it the survival of the individual? Of the species? Of the habitat or ecosystem? These three - individual, species, habitat - are not necessarily compatible or mutually reinforcing in their goals and actions.
If we set aside the dewy-eyed arguments of altruism, we are compelled to accept that individual survival sometimes threatens and endangers the survival of the species (for instance, if the individual is sick, weak, or evil). As every environmental scientist can attest, the thriving of some species puts at risk the existence of whole habitats and ecological niches and leads other species to extinction.
To prevent the potential excesses of egotistic self-propagation, survival is self-limiting and self-regulating. Consider epidemics: rather than go on forever, they abate after a certain number of hosts have been infected. It is a kind of Nash equilibrium. Macroevolution (the coordinated emergence of entire groups of organisms) trumps microevolution (the selective dynamics of species, races, and subspecies) every time.
This delicate and self-correcting balance between the needs and pressures of competing populations is manifest even in the single organism or species. Different parts of the phenotype invariably develop at different rates, thus preventing an all-out scramble for resources and maladaptive changes.
This is known as "mosaic evolution". It is reminiscent of the "invisible hand of the market" that allegedly allocates resources optimally among various players and agents. Martin Nowak, a Harvard professor, argues that emergent cooperation is a fundamental principle of evolution, as basic as natural selection and mutation.
Moreover, evolution favors organisms whose rate of reproduction is such that their populations expand to no more than the number of individuals that the habitat can support (the habitat's carrying capacity). These are called K-selection species, or K-strategists and are considered the poster children of adaptation.
Live and let live is what evolution is all about - not the law of the jungle. The survival of all the species that are fit to survive is preferred to the hegemony of a few rapacious, highly-adapted, belligerent predators. Nature is about compromise, not about conquest.
Sam Vaknin ( http://samvak.tripod.com ) is the author of Malignant Self Love - Narcissism Revisited and After the Rain - How the West Lost the East as well as many other books and ebooks about topics in psychology, relationships, philosophy, economics, and international affairs.