In the table above there are seven causes for climate change identified, plus two factors that can cause spurious changes in the measurement of climate change. This list is not exhaustive. There is no need to invoke increases in carbon dioxide and other greenhouse gases as major factors in climate change in the past, nor is there any solid evidence to indicate they will play a major role in future climate change . In the next two sections we comment on some aspects of climate change including causes and errors in interpretation and measurement. One is impressed how the climate modelers continued tuning of their climate models seems to closely parallel to the invention of epicycles used to rescue the Ptolemaic system.
Natural variability is very small.
The fact that climate responds by returning to its pre-perturbed state means that the climate system has a fixed set point and is constantly trying to return to that point. In other words, large fluctuations in climate can only occur if they are forced by changes in external boundary conditions. Changes in solar luminosity are the major driver of climate change in the 20th century and earlier as shown by the third figure on our home page. The greenhouse effect models predict most of the warming will occur after 1940 when most of the carbon dioxide entered the atmosphere. The warming however occurred mostly before 1940.