One might also divide between those who have done their homework and those who haven't. Both CO
2 increase and the
Milankovitch cycles (the orbital shifts that cause ice ages to come and go when the continents are aligned such that both poles can freeze) are known as forcing factors. The question is which forcing factor is contributing more and faster to climate change. That's a very answerable question. CO
2 is the larger forcing factor, and the Milankovitch cycles are a very slow (glacially slow) forcing factor. At the current rate of burning fossil fuels, the Milankovitch cooling factor is being submarined. As glaciers and ice caps melt, as methane thaws, as CO
2 continues to be burned, the Milankovitch cycles will become a very minor factor.
Yes, there is a slow steady long term cooling trend observable in the temperature record that is attributed to Milankovitch. This trend ended in the mid 1800s, when humans started seriously burning fossil fuels. The pre Civil War cooling trend produced a much slower cooling trend than the warming trend we've seen since. Fossil Fuel forcing is thus observably significantly greater than Milankovitch forcing.
There are a large number of forcing factors, most of which contribute very visible and readable signatures in the temperature records. A big volcanic eruptions cause several cool years. The
solar cycle causes a very reliable 11 year warming and cooling trend.
EL Nino / La Nina is less predictable, causing warm or cool bumps that generally last less than a year. Continents move, blocking or enabling warming currents that can prevent polar ice from forming. Plants suck CO
2 out of the atmosphere, converting the carbon into coal, gas or peat, generating a very long slow steady cooling trend. With all of these effects happening at once, the temperature curve is very messy indeed, but it is still possible to get a pretty good grip on how strong and how fast any given factor works.
That is, if one not politically motivated to avoid learning climate science. Republicans and Libertarians recently convinced themselves that the solar cycles were about to stop based on a very thin conjecture. They didn't. 1998 was a record setting warm year, with a solar cycle peak stacked on top of a big El Nino. When both those factors went away for a time, we set no more global heat records for several years. They declared global warming to be over. It isn't. This year we have another big El Nino stacked on another solar peak and an extra decade's worth of CO
2 in the air. We will be setting more records.
Mother nature just isn't influenced by political theories, but this won't prevent those with political interests from coming up with a new reason to disregard the science. Time proves them wrong, but doesn't prevent them from coming up with a new pseudo-science conjecture.
Ah, well.