Reference
Harries, J.E. 2000. Physics of the earth's radiative energy balance. Contemporary Physics 41: 309-322.
What was done
In the words of the distinguished author, Professor John Edward Harries, "the purpose of this paper is to review the status of research into one of the most challenging and important problems facing physics today: how does the atmosphere moderate the radiative energy balance that determines the earth's climate?"
What was learned
Of this problem, Professor Harries says "progress is excellent, on-going research is fascinating, but we have still a great deal to understand about the physics of climate." Hence, we are reminded to be humble. "We must exercise great caution," he says, "over the true depth of our understanding, and our ability to forecast future climate trends." As an example, Professor Harries states that our knowledge of high cirrus clouds is very poor, noting that "we could easily have uncertainties of many tens of W m-2 in our description of the radiative effect of such clouds, and how these properties may change under climate forcing," which is extremely critical in view of the fact that the radiative effect of doubling the air's CO2 content is only on the order of 4 W m-2. It is, therefore, truly an understatement to say, as he does, that "uncertainties as large as, or larger than, the doubled CO2 forcing could easily exist in our modeling of future climate trends, due to uncertainties in the feedback processes." Furthermore, because of the vast complexity of the subject, the learned doctor rightly declares that "even if [our] understanding were perfect, our ability to describe the [climate] system sufficiently well in even the largest computer models is a problem."
What it means
If we need to tell you what Professor Harries musings mean, we're all in deep trouble. And it appears we really are, as the political process moves inexorably forward in a futile attempt of those who know best to play God with the planet and reset its global thermostat on the most shaky of scientific grounds. Spitting into the wind would be as effective; for our ill-advised efforts will only return to plague us. It would be far better to do nothing at all in our present state of knowledge; but hubris always seems to trump humility.