Natural cycles ALWAYS change climate. One of the biggest cycles is the Pacific Decadal Oscillation (PDO). It shifts from warm to cold every 20-30 years, or on an inter-decadal time scale. This is directly related to sea surface temperature. The PDO’s temperature variance over more than 100 years can be viewed in the graph below. A common thread to PDO and climate is unmistakable.
Observed monthly values for the PDO (1900–2010).
See here and here.
Even though the Atlantic is a significantly smaller body of water than the Pacific, it has similar effects on climate. It has what is typically known as the Atlantic Multidecadal Oscillation (AMO). It has a quasi-cycle of warm to cold every ~70 years. Both the PDO and AMO are directly affected by other natural cycles.
Other natural cycles include Milankovitch Cycles (earth’s wobble), cosmic rays from the sun (sunspot activity), X Rays, UV radiation, Total Solar Irradiation (TSI), 6 sunspot cycles (7 to 600 years), Rossby waves (RW), Quasi-decadal oscillation (QSO), cloud cover, Thermohaline circulation, El Nino Southern Oscillation (ENSO), volcanic eruptions, Ekman transport, Aleutian low (AL), Interdecadal Pacific Oscillation (IPO), Kuroshio Oyashio extension (KOE), and over 20 other major climate changers.
The above doesn’t include more than thirty minor cycles that are affected by TSI, just as the PDO/AMO are. Those include droughts, hurricanes, dust bowls, La Nina, El Nino, etc… It should be noted the PDO is not a single mode of temperature variability, but a conglomeration of several cycles. When each cycle peaks at the same time, one can expect abnormally high or low temperature variations, and high or low climate results.
Some still believe that CO2 is the greenhouse problem. Carbon Dioxide, the food for all plant life, is a considered a ‘pollutant’. While CO2 accounts for less than 1% of the atmosphere, only 3% of that 1% is created by man. CO2 must be produced to feed every plant and crop that exists. Back millions of years ago, CO2 concentration got up to 18x higher than today, when there was an explosion of life forms in the Cambrian Period. Even in the Jurassic period (when dinosaurs roamed) CO2 levels were as much as 9x higher. But there were no cars, or fossil fuel burning back then.
(See chart here.)
millions of years before present
[Source: Temperature reconstruction by C.R. Scotese; CO2 reconstruction after R.A. Berner; see also IPCC (2007).]
The above writers investigated the effect of CO2 emissions on the temperature of atmosphere. Computations based on the theory of greenhouse effect show that increasing CO2 concentration results in cooling rather than warming.
Today’s [CO2] of ~390 parts per million (ppm) is a mere blip on the radar screen compared to earth’s historic CO2 concentration. The distant past shows CO2 concentration peaking at 7000 ppm at times.
All temperature measurements were taken from tree rings; physical isotopes of carbon, hydrogen, and oxygen in decayed plants; coral annual growth bands; and numerous other sources.
Because earth was always a closed system, no discernable emissions or additions were ever incorporated into earth’s biosystem. No additional oxygen, carbon, or even carbon dioxide has been added, but continuously conserved. CO2 seems to be added by burning fossil fuels, but is removed by plants converting it back to carbon (sugars) and oxygen. This has been happening since the beginning of time.
o plant respiration: [6CO2 + 6H2O ==> C6H12O6 + 6O2]
o animal respiration: [C6H12O6 + 6O2 ==> 6H2O +6CO2 +energy]
If all the CO2 and O2 are not consumed in the respiration of all living entities, and all CO2 and O2 are not eventually regenerated, the atmosphere would register major changes. In 600 million years of history, both have always returned to normal levels.
After hearing AGW concerns, one would have many questions. Why is the major global warming molecule (water vapor) never mentioned? Why do General Circulation Models (GCMs) not use satellite data, when satellites can see though clouds? Why do researchers typically use artificially warm readings manipulated by the ‘Urban Heat Island’ effect?
And most interestingly, when increasing CO2 is related to increasing temperature, a close inspection of the data always reveals CO2 increases following increases in temperature. In Climategate [Brian Sussman], according to ice core records at the end of each of the last three major ice ages, atmospheric temperatures rose 400-1000 years before CO2 levels increased.
Of course, disbelief in a Grand Designer of all the observed cyclic variations can be a problem.