Scientists are unsure about "how it all began" (Big Bang theory etc). But, accepting that it all DID begin - somehow - then the formation of the solar system is well understood, and therefore the formation of the Earth 4.54 billion years ago is well understood. The theory of tectonic plates seems robust. Scientists have uncovered evidence from rocks, sediments, ice cores and so on that show that the planet has been through extremes of ice ages and very warm periods.

IF, if, if you accept the above then it is 100% clear that any changes to the climate until man emerged was 100% naturally caused.

Mankind (homo sapiens) emerged 200,000 years ago. Using the well-known analogy, using 24 hours to represent the age of the earth, homo sapiens emerged at less than 1 second before midnight. The industrial revolution began at an eye-blink before midnight.

Using common sense - how can 23 hours, 59 minutes, 59.99 seconds of natural climate change be altered in .01 of a second?

But what ARE the natural factors that affect the climate.

NOBODY KNOWS THEM ALL.

Many factors ARE known, although the extent of the impact of each is unknown. Here are a few: tectonic plate movements; the activity of the sun; the tilt of the Earth's axis; the non-circular orbit of the Earth; volcanic activity; the Moon's pull on the oceans. But there are bound to be others - if you follow the climate blogs then every week new factors emerge - the effect of cosmic rays on cloud formation being a recent one for example.

Note that these are just some of the KNOWN, PRIMARY factors.

The primary factors combine to give the Earth, at a certain moment, certain conditions that will yield a climate - cold, warm, dry, and so on. The climate thus formed will then produce secondary factors - more or less ice cover, more or less ocean warming; more or less vegetation and so on. These in turn interact with each other - and the ongoing primary factors - to cause climate change.

And nobody knows how it all works. Nobody can EXPLAIN why the Earth has oscillated between warm and cold.

And if scientists cannot explain how the NATURAL forces work, it seems bizarre that they claim to KNOW how human forces interact with those unexplained natural forces.