Are temperatures rising?
It has warmed just over one degree centigrade since 1880 when the Little Ice Age was ending and we began to keep accurate temperature records. However, we are in one of the coolest periods in the Earth’s history, so that the warming has been quite beneficial. Dozens of people have attempted to reconstruct the Earth’s temperature history using a wide variety of evidence or indicators over geologic time of hundreds of millions of years. None can be said to be perfectly accurate, but all recognize the coldest periods with ice covering much of the planet, to the warmest periods of dense vegetation when the dinosaurs roamed the Earth.
In 1950, according to NASA's Goddard Institute for Space Studies, the mean surface temperature of the Earth was 14 degrees centigrade (C), which is 57 degrees Fahrenheit (F). During the last 420,000 years it varied from a low of 5C/41F to a high of 17C/63F, a range of 12C/22F.
Toward the bottom of the range it was cold enough for glaciers to increase in size, and toward the top, it was warm enough for them to melt. The colder years are referred to as ice ages and the warmer years as interglacials.
Current climate scientists have attempted to simulate the Earths’s climate with mathematical equations which contain the variables they believe to be the most important drivers of our planet's temperature. They do this while ignoring factors they know little about, yet common sense would make one believe them to be important. These include:
Seasonal changes in the Sun's radiation
Energy flows from ocean to air and oceans to land
The balance between Earth's water, water vapor and ice
The impact of clouds,
Mass changes between sea level, ice sheets and glaciers
The role of vegetation
Tectonic movements on the ocean floor
Differential movement of the earth’s crust and its molten core.
Perhaps even more important is that they ignore the known variables regarding our solar system. Over the history of the Earth, its temperature has varied over thousands of years due to its location in the solar system, a variation that is greater than most people recognize.
- The Earth's orbital path around the Sun varies its eccentricity every 100,000 years, changing its distance from the Sun from 83 to 120 million miles. Currently, as you learned in grade school, we are 93 miles away. Obviously, the closer we are the warmer the Earth is, and vice versa.
- A second major factor is that, over every 41,000 years the tilt of the Earth on its axis varies from 22.7 degrees to 24.5 degrees altering its seasonal climate. The inclination is now 23.7 degrees.
- NASA describes the third factor as follows:
"As Earth rotates, it wobbles slightly upon its axis, like a slightly off-center spinning toy top. This wobble is due to tidal forces caused by the gravitational influences of the Sun and Moon that cause Earth to bulge at the equator, affecting its rotation. The trend in the direction of this wobble relative to the fixed positions of stars is known as axial precession. The cycle of axial precession spans about 25,771.5 years.
"Axial precession makes seasonal contrasts more extreme in one hemisphere and less extreme in the other. Currently perihelion occurs during winter in the Northern Hemisphere and in summer in the Southern Hemisphere. This makes Southern Hemisphere summers hotter and moderates Northern Hemisphere seasonal variations. But in about 13,000 years, axial precession will cause these conditions to flip, with the Northern Hemisphere seeing more extremes in solar radiation and the Southern Hemisphere experiencing more moderate seasonal variations.
A fourth factor relates to the Sun, which has its own cycles of greater or lesser radiance. We discovered the cycles 250 years ago and have charted 24 eleven year cycles of greater or lesser sunspots, a high number of which indicate increased radiation. We find they affect Mars and Saturn just as they do Earth, but they are not considered in climate models. It should be obvious that mankind’s role in determining the Earth’s temperature is somewhere between insignificant and zero.
Learn more about this topic from NASA.