The basic accepted definition of global warming is a gradual increase in the temperature of the earth’s surface since about the year 1850. The Intergovernmental Panel on Climate Change (IPCC) adds that global warming is caused primarily by human activities, and some believe that it could result in run-away increases in atmospheric and land temperatures.
The human activities that are believed to contribute significantly are the industrial emissions of fossil fuel burning since the mid 1850s. The theory goes that the increase of fossil fuel burning has resulted in an increase of the earth’s atmosphere absorption of the greenhouse gas carbon dioxide, which relates to an increase in global temperatures.
A detailed graph study of average global temperatures reveals that it is incorrect to state that the cause of any temperature increase is mostly due to human activities. Yes it is correct to state that mean temperatures have generally increased during the past 150-years. However, it is incorrect to imply that temperatures have increased steadily, or are in an unstoppable runaway climb.
Figure 5 to the right, actually shows a very uneven increase in temperatures for the United States since the year 1880 (global temperatures are similar). Notice the 2 very warm periods in the 1930s and 2000-2007, and a quite cool period sandwiched between the other global warming cycles (shaded in blue)
Figure 5: From NASA United States. Temperature trend shows a peak in the1930s when carbon dioxide emissions were down (figure 7), and cooling from 1942 to 1988 when carbon dioxide emissions were increasing. The global temperature trend was very similar to the trend shown here. (click image to enlarge)
It will be shown later in this e-book that all global warming cycles have twin temperature peaks separated by about a 70 year period, and that this has historically occurred during all 5 global warming cycles during the past 1,000 years. Similar cycles are also seen within the larger mega 116,000-year cycles during the past 460,000 years. These cycles are discussed in the next chapter.