Global Warming: A Summation

I believe it would be a good thing if I were to go through the major points of my Global Warming posts to show how it all fits together. Otherwise, it is entirely too easy to lose the forest for the trees.   

The task of the very first post, The Great Global Warming Scam, was to demonstrate the contention that “the science is settled” to be false. This was done by the simple means of showing a very long list of distinguished scholars who disagreed with those who believe in Anthropogenic Global Warming (AGW). For most of these scholars, the disagreement was with the “anthropogenic” part of the phrase, not the “global warming” part. As virtually all of them would agree, there have been periods of global warming in the past. In addition to the list, the post included links to the scholars’ curricula vitae so that readers could judge for themselves the expertise of the scholars.

The burden of the second post in the series, The Basic Physical Processes of Greenhouse Gas Warming, was to set the stage for further discussion by explaining the basic physics of greenhouse gas warming. This included the basic concepts of temperature, the dual particle-wave nature of quantum mechanical entities such as photons, and the nature of collisions between photons and molecules such as CO₂ molecules.

In the third post, An Infrared Photon’s Life in The Atmosphere, it was demonstrated that most CO₂ molecules become saturated with infrared photons and can absorb no more until they re-emit absorbed photons. This was done by using the quantized energy levels of the CO₂ molecules and the long life of excited states relative to the photons’ flight-times between molecules. It was shown with relatively conservative approximations that among a cohort of photons emitted by the Earth’s surface at one particular instant in time, the very first would be lost to  space after approximately 66 collisions with CO₂ molecules taking 66 microseconds. The rest of the photon cohort, diffusing through the molecules, will reach the top of the troposphere sometime later, but the amount of time it takes for most of them to diffuse out is well below a second. It may be a shock to many who have only heard AGW propaganda, but infrared radiation is not trapped in the atmosphere by CO₂, but its escape back into space has only been delayed by diffusion.

By the fourth post, Global Warming Data, we were ready to take on the main part of the AGW debate by looking at some basic data. First, we looked at some historical data of temperatures over the past century or so. There are five major data sets of global temperatures versus time, By “global temperature” I mean an average at a single time of temperature over the surface of the globe. With three of the data sets, the basic data was obtained by temperature measurements at ground stations around the world. This gave data at specific positions without any data for much of world, especially over seas and oceans. This means temperature at these other positions would have to be interpolated from the measured temperatures in order to calculate the average, leaving the accuracy suspect. Two of the data sets using measured data from satellites get around this problem by the satellites directly integrating temperature over portions of the Earth’s surface. The entire surface of the Earth is completely covered by their orbits. For this reason the two satellite data sets should be considered as intrinsically more accurate than the ground station sets. The two satellite-measured data sets are maintained by the University of Alabama, Huntsville (UAH) and the Remote Sensing Systems group (RSS). The three ground-station data sets are maintained by NASA’s Goddard Institute for Space Studies (GISS), the National Climatic Data Center (NCDC) of the National Oceanic and Atmospheric Administration (NOAA) , and the  Climatic Research Unit (CRU) of the University of East Anglia.

While detailed accuracy of the NCDC data set may be questioned, it does show three periods of temperature trends that are universally acknowledged. The graph of that data is shown below.

This plot shows a warming between about 1917 to 1940, a slight cooling from 1940 to about 1975, followed by a warming period between 1975 to around 2000. In addition it shows a period of relatively constant temperature between 2000 and 2014 that is not so universally accepted, the so-called “pause” in global warming.

Now suppose you were to plot all five data sets on the same graph. The result would be the noisy display shown below.

A standard method to filter out noise from the data is to to do a least-squares fit of some low-order polynomial to the data, perhaps piecewise over sub-intervals (as I am sure was done in this case). This task was performed by a physicist named Chip Knappenberger, who then took the first derivative of the fitted polynomials to get the rate of temperature change for each series. The plotted results are shown in the figure below.

For those not conversant with differential calculus, the first derivative of a function of time is the function’s instantaneous time rate of change. As long as a point in the first-derivative series is positive, temperature is still increasing. As you can see from the figure, all five major globally averaged temperature series show cooling since sometime in 2000. The two more accurate satellite-measured series (UAH and RSS) show cooling since about 1999. This all has occurred while CO₂ concentrations have steadily increased unabated. The only possible conclusion is that global temperatures are are not as sensitive to CO₂ concentrations as many have thought. Also, we can conclude that the so-called “pause” in global warming is actually a period of global cooling.

But to show that the AGW hypothesis is false, we must have an explanation for the temperature rise between about 1975 and 1999, as well as an explanation for the observed cooling thereafter. The first part of the end argument was to show that cloud cover is essentially cooling and that less cloud cover will cause warming. It was the burden of the post Clouds and Global Warming to show this was the explanation for the temperature rise between 1975 and 1999. The research of Roy Spencer of UAH showed that a one to two percent decrease in cloud cover would be sufficient to explain the temperature rise. Totally independent research by Ryan Eastman and Stephan G. Warren, published in the Journal of Climate and entitled A 39-Year Survey of Cloud Changes from Land Stations Worldwide 1971-2009: Long-Term Trends, Relation to Aerosols, and Expansion of the Tropical Belt, demonstrated that was about the same reduction as was observed over all continents during that time period.

Now that we have an explanation for the warming, we need an explanation for the subsequent cooling, and it would be a good thing to find the physical mechanisms for the changes in cloud cover over time. This was the subject of the post Solar Power Output and Global Warming. A connection was shown between solar power output and the amount of cosmic radiation that could reach the lower atmosphere. There cosmic rays could ionize airborne particulates that would act as nuclei for water condensation to form clouds. The greater the solar power output, the greater the solar wind that would sweep the ionizing particles composing much of cosmic radiation away from the inner solar system, thus reducing cloud formation and increasing global warming. If the intensity of the solar wind lessened because the sun’s power output decreased, more cosmic radiation could penetrate the atmosphere, form more clouds and cool the planet.

To demonstrate experimentally that cosmic radiation had this effect of forming clouds, the CERN physicist Jasper Kirkby formed a group to study the problem. They used a CERN particle beam at various intensities simulating cosmic radiation that was directed to a cloud chamber filled with air to represent the lower atmosphere. They were able to demonstrate that cloud condensation nuclei were formed at rates to explain the changes of cloud cover during the warming period, and they published their results in the journal Science. See here for the abstract and links to the full paper. The post also noted that throughout the period from 1975 to 1999, the sun was increasing its power output, but since then has been decreasing in power output.

The import of all this lies in the fact that the Sun was increasing in power output during the periods of global warming, and therefore allowed less cosmic radiation to help form clouds. This is an explanation of why cloud cover decreased during the 1975-1999 warming period that we noted in the post Clouds and Global Warming. Also, during the present global warming “pause” that is actually a cooling, the Sun has been reducing its power output. We now have a complete, experimentally and observationally verified theory of the observed global warming that does not involve CO₂.

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