What caused the Ice Ages?

Angela

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I've heard a meteor, a wobble of the earth's axis, and on and on. This is a new one so far as I know.

See:
https://news.berkeley.edu/2019/04/1...when-tropical-islands-and-continents-collide/

"University of California scientists think they know why Earth’s generally warm and balmy climate over the past billion years has occasionally been interrupted by cold snaps that enshroud the poles with ice and occasionally turn the planet into a snowball.The key trigger, they say, is mountain formation in the tropics as continental land masses collide with volcanic island arcs, such as the Aleutian Islands chain in Alaska.
Earth’s climate is, to a large degree, driven by the amount of carbon dioxide in the atmosphere, which traps heat and warms the planet. While fossil fuel burning since the Industrial Revolution has driven CO2 levels to heights not seen in 3 million years, CO2 levels have been even higher in Earth’s past, coinciding with warm periods when no major ice sheets existed.
In fact, Earth’s default climate seems to be warm and balmy. Periods with no glaciers dominated for three-quarters of the past 1 billion years.
Yet, half a dozen ice ages chilled Earth during that time, two of them severe enough to turn the planet into a Snowball Earth with ice covering much of the surface. What caused these frigid interludes?
In a study appearing in this week’s edition of the journal Science, the team concludes that when volcanic arcs collide with continents in the tropics — an inevitable consequence of the planet’s constantly moving tectonic plates — they trigger global cooling, resulting in a glacial climate with extensive ice caps."
 
Interesting theory. It's also a long way from what I thought. I have always believed that the earth's orbit around the sun is not always the same, oscillating, in periods of thousands of years, between a moment of maximum remoteness, in which the earth maintains an orbit much farther from our star (the apogee), when then a glaciation takes place, and a moment of minimum remoteness of the sun (the earth maintains an orbit much near - the perigee), when a period of great warming occurs. I believed that we would be living a moment of perigee that, combined with the effect of the accumulation of greenhouse gases in the atmosphere, was causing an overheating of the planet. IMO.
 
In fact, in summer the earth is far away from the Sun, and in winter, it is close. What matters is not difference in distances, but inclination.
 
They might be right about the process but overemphasized the scale of the effect, I suppose. They totally ignored effect of green life on sea and land, way higher CO2 level in the past (up to 20 times), sun getting hotter with age, and interior earth getting cooler, so less intense volcanism with time. There are more moving parts that they think.
 
I wonder whether the IPCC models take this into account.
I don't think so.
How can these climate experts be so sure about these models?

Oh, I know what they will tell.
Because of this effect, the earth should have cooled down 1° C, instead of going up 1° C, humans are responsable for 2 ° C. Double doom.
 
In fact, in summer the earth is far away from the Sun, and in winter, it is close. What matters is not difference in distances, but inclination.
I don't get. When it's summer in North hemisphere, it's winter in South hemisphere, and when it's winter in North hemisphere, it's summer in South hemisphere.
 
I don't get. When it's summer in North hemisphere, it's winter in South hemisphere, and when it's winter in North hemisphere, it's summer in South hemisphere.

it's the inclination of the earths rotation axis compared to the perpendicular to the plane in which the earth rotates around the sun

this explains the seasons, but it has nothing to do with climate
 
it's the inclination of the earths rotation axis compared to the perpendicular to the plane in which the earth rotates around the sun
this explains the seasons, but it has nothing to do with climate
Sorry. Now I get what he meant. I thought he was talking on the distances from Earth to sun along the elliptical route and their coincidence with seasons. I must have thought that because I don't see the distance itself as an explanation for the seasons. The inclination matters, yes, but not because the distance, i.e., not because one hemisphere is more distant or closer than the other. It's the angle of incidence that matters, even along the day, in direction to sunset. Indeed, on Northern hemisphere, winter happens when Earth is closest to the sun, and summer when it's farthest away. So, it's not a matter of distance, but of inclination. Hence my question.

In fact, in summer the earth is far away from the Sun, and in winter, it is close. What matters is not difference in distances, but inclination.
 
See:
https://www.youtube.com/watch?v=WLRA87TKXLM

What some scientists have speculated in the past is that perhaps the Ice Ages are caused when the earth "wobbles" on its axis, i.e. the angles are different. At least, that's how I understood it.
 
I'm going to go out on a limb here and say lack of cow flatulence. Or maybe there were very few sunspots, which is what is reputed to have caused the Little Ice Age in early modern times.
 
I wonder whether the IPCC models take this into account.
I don't think so.
How can these climate experts be so sure about these models?

Oh, I know what they will tell.
Because of this effect, the earth should have cooled down 1° C, instead of going up 1° C, humans are responsable for 2 ° C. Double doom.

it's very likely that they ignored all those new continents in tropics in last 70 years
 

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