How does one respond to such a statement?  If you believe it, you shout Amen! and Be damned! to anyone who stands in your way.  But if you don't????  In the minds of the true believers, you're either crazy or over-cautious, either one of which maladies brands you as half-baked or less.  But are the zealots right?  Let's look at the facts and consider some of the reasons why one might not want to be in a hurry to jump on the climate change bandwagon.

First of all the underlying premise: Do we really have a complete and total understanding of the functioning of earth's complex climate system?  Hardly.  In fact, if one were to poll all climate scientists on the planet, it is our firm belief that not a single one of them would answer this question in the affirmative.

So what does this fact suggest about the second part of our hypothetical news release, the part that urges us to phase out fossil fuels in an attempt to dramatically reduce anthropogenic CO2 emissions?  To our minds, it is a blood-red flag that literally cries out for caution.

For starters, it is hubris of monstrous proportion to think that we are even close to comprehending all the intricacies of such a complex system as that which controls earth's climate.  Many of its numerous elements, both physical and biological (each of which interacts with, and influences, all the others), are still mini-mysteries in their own right.  In fact, we are but children in our ability to even identify all the pieces of the many different puzzles they represent, much less decide how they fit together to define the issue and prescribe a course of action.  Then there's the fact that global warming is not even the whole issue!  CO2 is a powerful aerial fertilizer; the more of it there is in the air, the better plants grow.  Do we really want to act at cross purposes to this great biospheric blessing?  Clearly, the subject is complex, so let's take a look at some of these points in more detail.

To begin at the beginning, does anybody believe that all we have left to do in the realm of climate modeling is "dot the 'i's and cross the 't's"?  Or maybe carry out some model calculation to one more significant digit?  In listening to the chorus of voices lamenting the dismal prognosis for our planet if we do not act now to reduce CO2 emissions, one could get the impression that climatology is one of the world's more exact sciences, and that its practitioners can forecast the future with great skill.  Nothing, however, could be further from the truth, especially with respect to the question of rising atmospheric CO2 levels and their potential to induce significant climate change.

Consider just one element of earth's climate system; consider clouds.

Clouds cover approximately half the surface of the earth at any given time and exert a great influence on its climate.  They reflect incoming solar radiation from the sun and thereby cool the planet's surface.  They also intercept outgoing thermal radiation emitted by the earth and reradiate it back to the surface, thereby warming it.

Which effect predominates?  It all depends.  Are clouds more prevalent in the day or at night?  In summer or winter?  Spring or fall?  Are they located high in the sky or close to the ground?  Are they composed of many small particles or fewer large ones?  Are the particles mostly ice crystals or are they water droplets?

How will an increase in the air's CO2 content impact clouds?  Will an initial impetus for warming lead to more evaporation, putting more moisture into the air and leading to the production of additional clouds that will reflect more solar radiation back to space and thereby cancel the original impetus for warming?  Will higher liquid water contents enhance the cooling properties of clouds more than their warming properties?  Do the answers to these questions depend on the vertical or spatial distributions of the clouds?  Are any other parameters involved?

What about the aerial fertilization effect of atmospheric CO2 enrichment?  Will it stimulate plants to produce and release more organic aerosols to the atmosphere, where they can serve as cloud condensation nuclei, stimulating the production of more and brighter clouds?  Will a CO2-induced increase in the flux of plant organic matter into the soil increase microbial activity there, leading to the emission of greater amounts of various sulfur gases to the air?  What fractions of these gases will be converted into particles that can function as cloud condensation nuclei?  Will there be enough of them to cancel the small greenhouse effect of the extra CO2?  Or is it possible that they could even overpower it and lead to global cooling?

And don't leave the oceans out of your deliberations.  Would a warming of earth's seas stimulate their biological productivity?  Does the aerial fertilization effect of atmospheric CO2 enrichment apply to marine plants as well as terrestrial ones?  Do the tiny unicellular plants that support everything from sardines to whales produce anything that could make its way into the atmosphere and influence the planet's cloud cover or the reflectivity of its clouds?

Then there's the human element.  Will increasing amounts of organic solutes from man's expanding agricultural and industrial operations influence the nucleating properties of natural atmospheric particulates?  Will increases in air traffic have an effect on either cloud amount or brightness?  What about shipping by sea?  Will it do the same?  Or the opposite?

What, in fact, about out-of-this-world phenomena?  Do variations in the magnitude and spatial distribution of the cosmic rays that impinge upon the earth affect its cloud cover?  What about variable solar activity?  The role of the solar wind?  Micro-meteors?  Galactic dust?

And how big are these several effects?  How much of an increase in cloud cover would be required to completely cancel the impetus for warming that is produced by a doubling of the air's CO2 content?  Ten percent?  One percent?  A tenth of a percent?  What about cloud reflectivity?  How much would it need to rise to lead to global cooling?  Five percent?  Five tenths of a percent?  What if changes in both cloud cover and reflectivity occurred simultaneously?

Do you know the answers to these questions?  Do you even think that the scientists who spend their entire lives studying these subjects comprehend all we need to know about them?  If not, why would you believe what politicians and government functionaries say?  Al Gore may believe what he preaches, even passionately so; but does sincerity make him, or anybody, right?  And do you actually think that the children who periodically scold us about CO2 and global warming know the answers to these questions?  If so, were they born with that knowledge?  If not, where did they acquire it?

A few decades ago we were worried about an impending ice age.  Currently, we're concerned about global warming.  But many scientists are beginning to suggest that large parts of the planet - if not all of it - could be due for another cold spell, courtesy, believe it or not, of rising CO2!  Which brings us to one of the key climatic elements of this newest theory: ocean currents.

What makes them go?  What makes them slow?  What makes them, well, you get the picture.  There are questions upon questions about climatic element after climatic element that we cannot answer to our satisfaction at the present time.  And that is why even cautiously-measured judgments about future climate oscillate with time, much like the climate itself.  Clearly, our collective climatic wisdom has not yet matured to where we can be confident about any prediction we might make about the future.

So, to bring back a popular phrase from the not-too-distant past: Question authority! Especially climate authority.  The crystal ball of the climatologists is still not crystal clear.  In fact, it's pretty cloudy.