What would happen if the earth's angle of inclination was 45 degrees instead of 23 degrees?
It would cause it to become colder.....
The change would be more complex than that. The poles would get more sunlight during various seasons, leading to greater melting at the poles with their "summer" seasons.
However, since this is not my area of expertise, I searched Google under the key words "earth inclination angle" to get these possible sources:
(Broken Link Removed)
http://en.wikipedia.org/wiki/Inclination
http://www.gi.alaska.edu/ScienceForum/ASF8/825.html
http://www.phy6.org/stargaze/Lseason.htm
You can also look up other terms for this same phenomenon indicated on these sites.
I hope this helps. Thanks for asking.