MAINTAINING FOCUS

CLIMATE CHANGE AND HUMAN ADJUSTMENT is proving to be so interesting that I need to keep a clear focus. Let's stay focused on climate change and the interaction between climate and human activity.
Weather and climate change are not the same thing. Weather is day-to-day stuff while climate change is the stuff of decades through to millenia. The exception to this is violent weather that seems to occur over the several years involving a climate flip-flop from warmer-wetter to cooler-dryer, as the story from the ice core research seems to indicate (I hope you turn to those two books I have mentioned for the background to this pronouncement).
Relative to the period of the ice-ages (beginning some 2.5 million years back), human study of climate is startlingly brief. What caused the ice-age period is not clear; however, prior to this , the earth was considerably warmer. Scientific study of climate is less than 200 years in the making and has only made serious advances in the last 40 years. The average temperature of the earth has been warming these last 30,000 years. Back then, ice sheets covered 30% of the earth's surface whereas currrent coverage is only 10%.
Climate is the engine that transports heat from the equator towards the poles. We all know it is hotter at the equator and gets less so as we go toward the poles. Unless heat could be moved, it would be hotter at the equator and much colder at the poles than is the case. This work is shared between two abundant fluids; water forming the oceans and the gases that compose the atmosphere above the seas. The basic forces that move the air are convection and the Coriolis effect. Heating at the equator causes air to rise, move toward the poles, descend as it cools, rise again and so on, steadily moving heat as it does so. Land complicates this flow by getting in the way of the lower winds. With more land north of the equator, the effects of the lands on wind flow are somewhat different between the northern and southern hemispheres. Land also divides the sea into regional oceans. Changes in temperature and salinity cause currents to flow in these regional oceans. Land also causes the regional oceans to have different sea levels and to have differing salinity, in addition to different temperatures. Because these regional oceans are connected to each other, currents flow between them to even things up. In the nature of things, evening up cannot occur due to the sun persisting in heating the earth, so the whole climate heat engine just keeps on running.
We humans live on the land and, apart from wind (and ocean currents if you happen to be seriously involved with getting around between bits of land), are hardly aware of the climate apart from the micro-shifts we call the weather.
The average temperature of the earth's surface at any period depends on many inputs. When lots of ice and thick clouds abound, the earth tends to be cooler. The climate engine does not run as fast because more heat is reflected and less heat reaches the surface of the earth. When carbon dioxide, water vapor, and methane concentrations increase in the atmosphere, heat is prevented from escaping by radiation causing the temperature to rise (the 'greenhouse' effect). During the ice ages the earth was cooler. In between ice ages, things warmed up. That the ice ages will occur can be predicted to some degree by variations in the path of the earth around the sun (causing it to be significantly nearer or further from the sun), oscillations in the angle of the earth's axis to the plane of its orbit, and by the temperature of the sun's surface. This was mathematically predicted before we had evidence of the ice ages.
Climate change causation is even more complicated than I make out and, even after the basic data were discovered, the development of useful models had to await the appearance of supercomputers to run the models that simulate climate change.
Although politicians make use of some results from science from time to time (Einstein's letter to FDR about the atom bomb and the likelihood of Hitler producing one early in WWII is one example), they seem nowadays to be more influenced by lobbying from powerful sectional interests. The rest of us have lost interest in science or, at worse, are skeptical about its supposed 'findings'. Until recently, scientific reports about climate change (if you disregard the occasional horror movie of episodes on Discovery Channel) got about as much regard as Noah may have received when he commenced building the Ark.
Well, this little foray into the science of climate and climate change is over for the moment. The next posting will seek to relate something of what has emerged about the great heat exchange engine (climate) and the effect of human activity.