A new study produced by a University of Wisconsin-Madison geoscientist and Northwestern astrophysicist presents an explanation of the fluctuations of the earth's temperatures in the past that highlights the complexity of the forces at work on the earth's climate and how much we still have to learn about them. The study maintains that the cycle of changes in the climate over the millennia is largely a result of changes in the amount of solar radiation, in part caused by small changes in the orbits of Earth and Mars.
While the notion that the impact on earth's orbital cycle on solar radiation levels is a significant factor determining global temperatures is anything but new, the team of scientists seem to have tied the phenomenon to planetary orbits in a more concrete manner than previous studies.
In an article summarizing the scientists' findings, the University of Wisconsin-Madison notes that the study "provides the first hard proof for what scientists call the 'chaotic solar system,' a theory proposed in 1989 to account for small variations in the present conditions of the solar system." Those variations over millions of years "produce big changes in our planet’s climate." Not only does the new discovery promise to provide a better understanding of "the mechanics of the solar system," but also "a better understanding of the link between orbital variations and climate change over geologic time scales."
UW-M provides some more details on the groundbreaking study:
Using evidence from alternating layers of limestone and shale laid down over millions of years in a shallow North American seaway at the time dinosaurs held sway on Earth, the team led by UW–Madison Professor of Geoscience Stephen Meyers and Northwestern University Professor of Earth and Planetary Sciences Brad Sageman discovered the 87 million-year-old signature of a “resonance transition” between Mars and Earth. A resonance transition is the consequence of the “butterfly effect” in chaos theory. It plays on the idea that small changes in the initial conditions of a nonlinear system can have large effects over time.
In the context of the solar system, the phenomenon occurs when two orbiting bodies periodically tug at one another, as occurs when a planet in its track around the sun passes in relative proximity to another planet in its own orbit. These small but regular ticks in a planet’s orbit can exert big changes on the location and orientation of a planet on its axis relative to the sun and, accordingly, change the amount of solar radiation a planet receives over a given area. Where and how much solar radiation a planet gets is a key driver of climate.
Over the ages, the subtle variations in the orbits of Earth and Mars, the scientists theorize, have impacted the amount of Earth's exposure to solar radiation and thus led to shifts in global temperatures, impacting the pattern of Earth's ice ages.
"The impact of astronomical cycles on climate can be quite large," explains Meyers, noting as an example the pacing of the Earth’s ice ages, which have been reliably matched to periodic changes in the shape of Earth’s orbit, and the tilt of our planet on its axis.
While evidence that the earth's orbital variations impact radiation levels and thus global temperatures does not of course mean that man is not in some way impacting the climate, studies like these inadvertently highlight that there are complex natural phenomena impacting the planet that are utterly out of our control and about which we still have much to learn.
This article has been revised for clarity.