why do long periods of global warming lead to ice ages?
In: Planetary Science
I’m no scientist, but I’ll give it a shot.
When the temperature increases, it causes the poles to start melting and therefore shed water, causing an increase in sea levels.
The increased sea level starts covering land where vegetation once grew. The vegetation is important because plants and trees contribute largely to the atmosphere that we breathe and live in. The atmosphere is what protects us from the hostile and cold environment of space. If we lose or severely deplete that thin protective layer, the planet cannot retain the heat it gets from the sun, and it gets cold enough to form ice over a lot (?most) of the surface (which causes more vegetation to die).
I think long periods of global warming can paradoxically lead to ice ages because they disrupt the Earth’s climate balance. When warming continues over millennia, it alters ocean currents and atmospheric patterns, causing changes in ice sheet formation and circulation
Depending on the layout of the continents at the time it can massively disrupt the ocean currents. For instance the northern part of the Atlantic has a circulation that sees warm water from the Gulf head up towards the British Isles, giving us our distinctive weather patterns (lots of rain, weirdly humid even when it’s cold, nothing like as cold as other places this far north) , and that current is also responsible for keeping the edge of the pack ice away from the Norwegian coastline. What drives that current is very salty water of generally Mediterranean origin coming out of the Straits of Gibralter on massive eddies and gyres cooling down and sinking off the coast of Canada/Greenland…. The problem is melting ice sheets deposit fresh water into that location and fresh water is a lot less dense than salt water so it interferes with the “pump” that drives the Gulf Stream. If that shuts down the ice will be down as far as Scotland pretty much in a couple of years. There have been other events similar to this in the past and the various sampling techniques available (mostly icecores and lakebed sampling) show the same thing, one year was normal, the next year didn’t have a summer adn the year after that the iceage was here for a while…. Once the ice gets established it reflects so much heat back into space that you need a very much higher CO2 level to trap enough to melt it….
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