The Climate of the Earth has been constantly changing during its entire 4.6 billion year history. Variations in our planet’s average temperature due to natural causes have ranged over a span of 60 degrees Fahrenheit. Most of the periodic temperature increases and decreases observed in human history are consistent with variations in the output of energy from our Sun. The mild heating and cooling periods seen since 1900 (each less than 2 degrees Fahrenheit) reflect changes in solar activity. The temperature of the Earth has never been constant.
Continental positions determine the distribution and circulation of heat on Earth and have a major impact on our planet’s long term Climate. As little as 70 years ago if a child or adult made note of the fact that our current continents could be fitted together like a jig saw puzzle, they were laughed at but in the1950s scientists proved that our continents had historically resided in different places on the globe. Sometimes the continents were near the equator, sometimes near the poles, sometimes they merged into a single land mass.
The largest changes take place over time periods of 20 to 100 million years. These changes, both gradual and catastrophic are associated with continental motions due to plate tectonics or continental drift.
Periodic changes in the Earth’s orbit also influence how energy that the Earth receives from the sun is distributed, resulting in our current era of recurring Ice Ages. The Earth is now experiencing the high temperature end of the latest Ice Age cycle. Both deep-sea sediment and ice core samples show that ice ages take place every 22,000 years. The Earth’s axis wobbles around a tilt angle of zero degrees in a cycle that requires 22,000 years to complete. At one end of the cycle the North Pole faces the Sun in the winter, while at the other end, the North Pole faces the Sun in the summer. The tilt angle relative to the sun also varies over a 41,000 year cycle.The annual orbit of the Earth around the Sun cycles between circular and elliptical every 100,000 years. These are called Milankovich cycles for the Serbian scientist who discovered them a century ago. Man’s presence and activities are insignificant as compared to natural cycles.
Most of the warming and cooling trends observed during human history operate on time scales of a ten to a thousand years resulting in temperature shifts spanning a range of about 7 degrees Fahrenheit . They arise from changes in output of energy and radiation from our Sun, according long-term and short-term cycles of solar activity. These cycles, have been documented using the recorded history of sunspots, aurora observations, radio-carbon dating techniques, and changes in solar radiance.
Changes in solar activity affect the stream of electrons, protons, and alpha particles emitted by the Sun which are called the solar wind. These changes have been observable in the form of auroras and more recently in the disruption of radio communications and electromagnetic devices.
Changes in average global temperature since 1900 are much more consistent with oscillations in solar activity and the average amount of energy that we receive from the sun than they are with the exponential increase in fossil fuel emissions. The Earth’s temperature increased from 1880 to 1935 as the Little Ice Age ended. It decreased from 1935 to 1980 and increased from 1980 to 1990 and has since leveled off. The temperature did not continuously and dramatically increase to mirror the increasing CO2 emissions.