By Dr. Dietrich E. Koelle
[Translated/edited by P Gosselin]
Fig. 1: Structure of the Milky Way (Wikipedia, NASA/JPL-Caltech/R. Hurt)
Drawing conclusions on the development of the Earth’s climate from climate change on Mars would be quite difficult because there is no concrete data from Mars. But it is considerably easier to do this in the opposite direction: The large climate changes on Earth that occurred cyclically about every 150 million years are traced back to a long-term fluctuation in cosmic ray intensity, or simply the radiation variation as to the various cosmic dust density conditions as the solar system traveled through the spiral arms of our Milky Way galaxy.
It is known that the solar system orbits about the center of the Milky Way every 220 million to 240 million years at a distance of 25,000 to 28,000 light years from the center. The Milky Way’s diameter is roughly 100,000 light years.
These radiation intensity fluctuations repeatedly led to global mean temperature extremes here on Earth that ranged from 0°C (Snowball Earth) to 28°C, which saw palm trees in Antarctica (see Fig. 2).
Earth is currently in the middle of an ice age
Approximately 2.5 million years ago a new large ice age began. It is one that we are not really aware of because we happen to find ourselves in one of the 10,000-year relatively warm but brief interglacial periods, which we call the Holocene.
These roughly 10,000-year interglacials have been occurring about every 100,000 years over the past million years.If these extreme temperature fluctuations occurred due to changes in radiation intensity, then they also had to occur on the other planets of our solar system, for example on Mars.As was the case on Earth, this means that considerably higher temperatures would necessarily been the case there 100 million years ago (also 270 million years ago). These warm conditions would have permitted liquid water to exist on the planet’s surface.
Recently traces of such water have been detected on multiple occasions by NASA.
Fig. 2: The temperature history of the Earth saw extreme fluctuations between the hot-house and ice age periods. The horizontal axis has a scale of hundreds of millions of years before present.