La Niña is coming. Global temperatures expected to fall. Global temperature has not risen since 1998.
What we know is that in AD 900 to AD 1300 there were dairy farms in Greenland, and the Vikings had colonies. The Inuit were caribou and to a lesser extent cattle herders. It was warm throughout Europe. Growing seasons were longer. We don’t know much about Polar Bears but clearly they survived. We don’t know about the South Pole Glaciers because no one had ever gone there. We do know that Earth abided.
About 1325 it rained a lot and began to get colder. Greenland became uninhabitable if you insisted on being a dairy farmer. The Vikings began to pull out. The Inuit came in, but could not sustain by herding reindeer and began to fish and hunt seals. The Earth grew colder. The Little Ice Age had begun.
By 1776 it was cold enough that cannon could be hauled across the frozen Hudson River to General George Washington on Harlem Heights. The cannon saved his army: Howe, having “won” at Bunker Hill in a Pyrrhic victory, was afraid to close with Washington’s Continentals, and by not eliminating the Patriot Army allowed the American Revolution to continue: but it was cold.
About 1825 the world began to warm. The warming trend continued until about 1970, halted, and by the late 1970’s there was concern about upcoming new famines and new ice ages: Global Cooling was the concern of Big Science and the coming doom was big at annual meetings of the American Association for the Advancement of Science.
We also know this: if you need to heat the Earth you need to heat the oceans. CO2 is a weak greenhouse gas overwhelmed by water vapor: that is, if the air is moist, the CO2 plays little to no part in the “greenhouse effect.” Thus CO2 mostly operates in cold, dry places, such as deserts. It has little effect at all over the oceans.
If I want to heat water, I do not get out my hair dryer and blow hot air across the pot. I heat the pot. If I want to heat oceans, the most effective way would be to blow off a volcano under water. Of course I have no control over those – nor can I predict when they will happen, but one such event can overwhelm all the other factors in my computer models.
Modeling the weather is difficult. Modeling climate is more difficult. Most of the equations cannot be solved and must be evaluated by brute force numerical analysis. This is difficult math and requires very expensive computers. Getting those computers requires grants. Getting those grants requires peer reviewed publications. Getting a positive peer review requires, usually, that you adhere to limits set by the “consensus” position. The consensus today is Global Warming despite the evidence that there is something wrong with the model. The consensus is intolerant of dissent from one side, but tolerated the “hockey stick” with unpublished secret algorithms for years.
And that is our present state, except that the weather observers – those who deal with data – tend to dissent from the Global Warming Consensus. They see trends but not the trends that the modelers see. Moreover, no model – none – can take the initial conditions of ten years ago and arrive at the present, much less track reality over the last hundred years.
Simple Bayesian Analysis says that if you have two mutually exclusive and expensive alternatives, then it is better to spend money reducing uncertainty than in preparing for either of the expensive alternatives. If the Earth is warming we have one course of action; if it be cooling we require another (and of course ice is a far greater danger if it comes). What we ought to be doing is better observations to see what is happening. When we do gather more data we find that the case for man-made Global Warming is not in general supported by the data. Solar output and volcanism are the major drivers of world temperature, and neither is entirely predictable.
Jerry Pournelle is an American Science Fiction writer, essayist and journalist. Visit his website: http://jerrypournelle.com