What are the significant factors that can cause variation in global temperature?

Question

I am interested in both man-made and natural phenomenem, things that are measureable and predictable rather than irregular and cataclismic events such as asteroid impacts.

Ideally, could you quantify the relative importance of these, perhaps with percentages. Thank you.

Answer 1

The main factors are variations in the Earth's orbital (Milankovitch) cycles, variations in solar output, and CO2 as a natural feedback and emitted by humans.  The current global warming is 80-90% caused by human CO2 emissions.

A discussion of all these factors is available in the link below.

Answer 2

That has changed dramatically over the last 100 years.  Here's a nice graph showing the changes, from the Source below.  It provides the relative amounts of each you're looking for, although you'll need to convert them into percentages:

http://www.globalwarmingart.com/wiki/Ima...

By the way excess water vapor CANNOT cause global warming, because it falls out as precipitation.

http://environment.newscientist.com/chan...

And the warming on Mars is due to other reasons.  It can't be the Sun, because most planets aren't warming.  

http://environment.newscientist.com/chan...

Answer 3

Good question, here's a link that list the fundamentals of priority.

http://www.eoearth.org/article/Causes_of...

Needless to say from your poser that natural balances are not readily measurable. It's not easy to correlate Ecological Homeostasis with man made influences. One is measurable the other isn't. But they do try, so that leaves only  the percentages of AWG only. Isotope's are the foundation of what GW is built on. Examples are: C12=99% natural occuring,C13=1% both, you can highlight which one you want.