What would happen to Earth's climate if the tilt of its axis became less than 23.5?

Answer

Well, the seasons would be different. As the tilt of the axis decreases, the changes in seasons would be less and less noticeable until there would be no change at all at a tilt of zero degrees.

A more interesting question would be what would the climate be like when the tilt is at any given angle.

Zero degrees - no change

5 degrees - small change, midnight sun only very close to the poles

10 degrees up to about 25 degrees - similar to what we have today

25 to 35 degrees - Interesting. Let's see - more extreme summers and winters.

Longer summer days, shorter winter days in the higher latitudes. The Arctic and Antarctic circle would be as far as 55 degrees north/south, which would put half of Scotland, to say nothing of Scandinavia, a great deal of Russia, the Baltic Republics, Canada, and all of Alaska except the southern tip, in darkness in late December and 24-hr light in June. The opposite can be said about the southern tip of South America. New Zealand would have an extremely short day (how short?) in June, and likely have frigid weather in June, similar to today's Finland in December.

The Tropic of Cancer/Capricorn would be at 35 north/south, which would give places like Syndey, Aukland, Buenos Aires, Cape Town as well as Tokyo, Oklahoma City, Los Angeles, a sweltering summertime climate simliar to Havana, Cuba, Florida today. We could go on and on.

35 to 45 degrees - This is even more interesting. Imagine the poles being temperate and the equator being frigid. Do a calculation of the average annual solar energy that impinges upon a given surface at a given latitude assuming a tilt of 45 degrees. Then do the same calculation for each season of the year.

45 to 90 degrees - More interesting even yet. Imagine the sun never setting at the north pole, being directly above.

First answer by Olphys. Last edit by ShmuelG. Contributor trust: 3 [recommend contributor]. Question popularity: 48 [recommend question]