I got a lot of answers to my questions about global warming last night while watching TV. There was a show discussing the issue on the History Channel. It was not sensationalist; there was no suggestion that we were in for a world of hurt until around the end of the century. But there was an explanation of what happened in the past millenniums when there was an increase in greenhouse gases and global average temperatures increased over 15F. In at least 2 cases there was mass extinction. The same was true when greenhouse gases decreased abnormally, except that it led to ice ages, including one where the entire globe was encased in ice. In all cases so far, the changes in carbon dioxide or methane concentrations in the atmosphere were natural. Cold spells are typically due to a change in the ellipticity of the Earth's orbit around the sun. When the orbit is elliptical, ice ages are more apt to occur. We are in an elliptical period right now, but global temperatures are rising. The most reasonable explanation is that greenhouse gases, most notably carbon dioxide, are increasing at a high rate. How do scientists know the concentration of carbon dioxide over the millenniums? They collect ice core samples from Greenland and Antarctica and determine the carbon dioxide concentrations in the ice strata. Maybe we really do need to make an effort to control greenhouse gases.
Oh, yeah. The hook to cars is that we need to drive smaller vehicles more efficiently and find alternate forms of energy for the cars, like electric motors. There is a pilot coal burning plant in Illinois that exhausts it's vapors underground. Maybe that concept will supply clean energy from a traditional source of electricity.
"How do scientists know the concentration of carbon dioxide over the millenniums? They collect ice core samples from Greenland and Antarctica and determine the carbon dioxide concentrations in the ice strata."
That is true. And we just went back several thousand years more due to the new science station in Antarctica. But higher resolution data are extracted from tree rings and carbon analysis. Also cores are taken in deep sea drilling operations which are analyzed for compostion.
Earth is always in an elliptical orbit. We are also wobbling about the spin axis, the change in climate due to this and possible explanation for the ice ages is called the Milankovitch Cycle. Its period is on the order of 10's of thousands of years. The most convincing data record is from Mona Loa on Hawaii where Thomas Keeling started montitoring CO2 levels in the last century.
The long records deal a lot with isotope ratios and compare on average three records to calibrate the histories. So Carbon and other chemicals are observed in sediment and ice cores and vary in how well things can be resolved based on how fast the substance was deposited and was able to trap the molecules with the signature.
