Global warming is caused by the Earth’s changing orbit

Myth:

Temperature changes are caused by changes in the Earth’s orbit, not by CO₂

Fact:

Over many millennia, the Earth’s temperature changes significantly. Those changes are set off by variations in the planet’s orbit, tilt and axial rotation (all of which are affected, in turn, by the gravitational pull of the larger planets). The change from an ice age to a thaw and back again is known as a Milankovitch Cycle. What happens is that once every 100,000 years the Earth’s orbit, tilt and rotation line up in such a way as to significantly change the amount of solar radiation reaching the planet. This in turn sets off a feedback loop that induces an ice age or a thaw. It takes between 5,000 and 20,000 years for the Earth’s temperature to make the change. It then remains stable until the next correlation of orbit, tilt and rotation occurs. The Earth emerged from the last ice age around 12,000 years ago and is not due to enter another for at least 10,000 years. 

Milankovitch Cycles are not the cause of our current global warming.  

Graph showing ice ages and thaws over the last 800,000 years [Source: Wikimedia Commons]

Sources:

Source: Alan Buis, “Milankovitch (Orbital) Cycles and Their Role in Earth’s Climate,” NASA, 27/2/20

Dr Dan Britt, “Orbits and Ice Ages: The History of Climate,” 2012. https://www.youtube.com/watch?v=Yze1YAz_LYM