Three of these five policy options are no-brainers.  Improving the efficiency of any human endeavor is nearly always good business, as is the improvement of soil management practices.  And who doesn't love trees?  Decarbonizing the world's energy system, however, may be the biggest "no-brainer" of them all, as it posits a cause for the global warming of the past century or so (a CO2-induced intensification of the atmosphere's natural greenhouse effect) that is by no means proven, and it would deny the planet a host of biospheric benefits it could dearly use.

Consider the fact that carbon dioxide is the primary raw material used by plants to produce the organic material out of which they construct their tissues.  Literally thousands of experiments have now proven, beyond any shadow of a doubt, that the more CO2 there is in the air, the better plants perform this vital function, a function upon which we, and all the rest of the animal world, depend for our very existence.  Consider also that with more CO2 in the air, plants do this job more efficiently - a virtue lauded by Victor when applied to industrial energy usage that is no less commendable when it occurs in the world of nature.

Now return to the idea of energy system decarbonization, which Victor rightly notes would penalize those activities that emit carbon.  Hoffert et al. (1998) have calculated that the amount of carbon-emission-free power that would be needed to stabilize the atmospheric CO2 concentration at an acceptable level (defined by the United Nations Framework Convention on Climate Change) is so large that it would require an international effort of the urgency and magnitude of the Manhattan Project or the Apollo space program (or, as someone once proposed in a book called Earth in the Balance, the post-World War II Marshall Plan).

Consider, last of all, Victor's startlingly frank summary statement that "for now, taking action on global warming is akin to buying insurance with an unknown premium against unknown hazards."  This is a strange insurance policy indeed.  In fact, it is even stranger than what Victor suggests; for we actually pay, and pay dearly, to deny ourselves known benefits, and this as a hedge against a phenomenon (global warming) that has actually been beneficial to date - extricating the earth from the grip of the Little Ice Age - and which could well be totally unrelated to the ongoing rise in the air's CO2 content.

Clearly, not enough thinking has gone into the formulation of policy options related to this subject.  In particular, the biological side of the carbon coin has been almost totally neglected; and we do no one any favors by ignoring this pertinent field of scientific research.  For a project as grand as the decarbonization of industrial society, we must consider all the ramifications of such a scheme.  And the consequence that is most assured is that the plant life of the planet would be denied the opportunity to rise to a new level of physiological prowess, which is something we may well need to feed the ever-growing numbers of our species and help preserve the planet's biodiversity.

Before playing doctor with the earth, we would do well to remember the prime directive of that worthy profession: first, do no harm!