Viewing a single comment thread. View all comments

ElleRisalo t1_jajfafd wrote

Reply to comment by dvogel in Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science by AutoModerator

Actually the tilt decreasing would increase the rate of extreme weather events. Every 26000 years or so seasons on the planet flip North to South. Or winter in the US would be in July, and Summer in Australia would be in July.

The most recent was about 18000 years ago now (that allowed people to traverse the Bering Strait and settle North and South America from Asia), or the last ice age we are currently coming out of. In another 8 to 10K years we will likely re-enter a minor ice age. This is due to the sheer volume of landmass in the North vs the South, and as such Snow sticks better...reflects more light back...so it stays colder, for longer, more snow, etc etc etc.

So as the tilt declines air and sea currents become more tropical (focused between the tropics and the equator) and as such more freakish weather can pop up almost anywhere at any time due to the increased amount of water entering the atmosphere due to the tropical heating effects on waters that didn't really experience it before.

As this procession continues weather patterns normalize as the system balances....and then like 13000 years later it starts to repeat as the function repeats itself in the inverse.

As for the measurements themselves based on tilt, they can be factored in, but it's largely irrelevant given the time scale of the procession 26000 years or so is a long ass time...and basically irrelevant for what happens in the next few hundred years.

For the most part you going to have same or similar weather right up until a couple centuries before it flips and starts going back the other way.

(If this makes sense. Explaining these types of procession can be tough at times.)

1

dvogel t1_jajh95j wrote

This NASA page says:

> The greater Earth’s axial tilt angle, the more extreme our seasons are, as each hemisphere receives more solar radiation during its summer, when the hemisphere is tilted toward the Sun, and less during winter, when it is tilted away.

It has this to say about the 26k year cycle you're referring to:

> Axial precession makes seasonal contrasts more extreme in one hemisphere and less extreme in the other. Currently perihelion occurs during winter in the Northern Hemisphere and in summer in the Southern Hemisphere. This makes Southern Hemisphere summers hotter and moderates Northern Hemisphere seasonal variations

So I guess I still have the same question, but complicated by the fact that models would have to account for a different effect in different hemispheres.

1