What caused the global warming that ended the last Ice Age?

Question

I'm very curious to find out what caused the global warming that ended the last ice age...as well as previous ice ages. I'm asking this because I keep hearing that humans and greenhouse gasses, and burning fossil fuels are the cause of the global warming. Since these things weren't around back then...I can only assume that it was some natural heating and cooling of the earth, but I want to hear what you have to say.

Thanks.

BTW, I'm not denying that the earth's temparature is slightly risen...I'm just confused as to how much of it is natural and would happen even if we completely stopped burning fossil fuels and producing greenhouse gasses.

Answer 1

hmmm,  ok since no one got it yet,  its the milankovitch cycles.  There are three cycles in which the earths axis and orbit changes gradually.  There is a rough 100,000 cycle in which the orbit becomes more elliptical, causing us to be farther away from the sun during the height of two of the seasons.  We have ice ages when we are at the farthest point away during the northern hemisphere summer, and winter.  We get like 21% less sunlight from the sun when at the far points from the sun during that time, so you can imagine how that would effect the northern hemisphere during the summer and winter.  The winters were brutally cold and the summers werent warm enough to melt the snow pack from the previous winter.  So there is how your ice age happens.  

Im not going over the other 2 milankovitch cycles because I dont think they are as important as the main, 100,000 year cycle, so look the other 2 up, Im not typing it out.

The ice age ends as the summers get warmer, and the winters get warmer as the orbit looses its eccentricity, and becomes more round over time.  Right now, we recieve 7% less sunlight during  2 seasons of the year, I dont know how its lined up right now, for which hemispheres.  It must not be enough for anyone to notice.

Answer 2

The glaciation cycles follow the Milankovitch orbital forcings, to a greater or lesser degree.

There is recent work which suggests that methane was a big factor.  Lots of shale rocks are too salty for microbes to exist, but when they are overlain by ice sheets fresh water gets forced down into them and microbes can grow and make methane.  When the ice sheets start to melt, methane escapes from the uncovered rocks and drive warming which helps to melt more ice (along with the increased solar gain from dark rock compared to reflective ice).

Answer 3

The basic explanation is the Earth's orbital (Milankovitch) cycles.  

http://en.wikipedia.org/wiki/Milankovitc...

These cycles are also amplified by various feedbacks.  For example, CO2 is less soluble in warmer water, so as the planet warmed due to the Milankovitch cycles, the oceans released more CO2, which caused further warming since CO2 is a greenhouse gas.

However, scientists know the current warming isn't due to these cycles.

"An often-cited 1980 study by Imbrie and Imbrie determined that 'Ignoring anthropogenic and other possible sources of variation acting at frequencies higher than one cycle per 19,000 years, this model predicts that the long-term cooling trend which began some 6,000 years ago will continue for the next 23,000 years.'"

http://en.wikipedia.org/wiki/Milankovitc...

http://www.sciencemag.org/cgi/content/ab...

Answer 4

Many scientists have come to the hypothesis that a cataclysmic event caused the ice age.  The best theory is that the earth was struck by a meteorite.  The result was that ash, dirt and silt sprayed up into the upper atmosphere causing perpetual night for most, if not the entire, earth.  The earth, not feeling the sun's warmth, iced over.  Now this seems much, but if a meteor of significant enough size did strike this planet then I can understand how enough dirt and ash would be able to block out the sun for years.

Anyway, when finally the dust and ash made its way back to earth, clearing the atmosphere enough so that the sun could warm it again, you can imagine that it would have ended the ice age.  I do not believe it had anything to do with the kind of global warming we are experiencing today.

Anyway that's my hypothesis.  I hope it helps.

Answer 5

um the eath got way to hot beasce of the space comet that it hit than boom here comes

ice age

Answer 6

This was on the History Channel last week. It is strongly speculated that a shift of 7 degrees (location shift - not temperature shift) of the earth's axis did it. This shift exposed certain ocean currents to different temps than during the ice age.

Answer 7

<<<Carbon dioxide did not cause the end of the last ice age, a new study in Science suggests, contrary to past inferences from ice core records.“What this means is that a lot of energy went into the ocean long before the rise in atmospheric CO2,” Stott said. But where did this energy come from" Evidence pointed southward.Water’s salinity and temperature are properties that can be used to trace its origin – and the warming deep water appeared to come from the Antarctic Ocean, the scientists wrote. This water then was transported northward over 1,000 years via well-known deep-sea currents, a conclusion supported by carbon-dating evidence. In addition, the researchers noted that deep-sea temperature increases coincided with the retreat of Antarctic sea ice, both occurring 19,000 years ago, before the northern hemisphere’s ice retreat began. Finally, Stott and colleagues found a correlation between melting Antarctic sea ice and increased springtime solar radiation over Antarctica, suggesting this might be the energy source. As the sun pumped in heat, the warming accelerated because of sea-ice albedo feedbacks, in which retreating ice exposes ocean water that reflects less light and absorbs more heat, much like a dark T-shirt on a hot day. In addition, the authors’ model showed how changed ocean conditions may have been responsible for the release of CO2 from the ocean into the atmosphere, also accelerating the warming.>>>

Pre- humans, the earth froze and thawed on its own. it has a cycle. but humans are putting out too much co2 and killing the trees and plants that use the co2, so its just staying there, not being absorbed, collecting. this thickens the atmosphere and the Earth's heat cannot evaporate through to go into space. we're s******g ourselves over.

Answer 8

Well, That was a natural shift, which they do have, but in graphs, the rising temperatures are at over the rate of ending the ice age. The cause and end of the ice age is very contraversal, but let me say this, that global warming can cause ice age, by stopping the cold fronts and it would be an ice age on one half of the earth, and getting hotter on the ther side, with no middle

Answer 9

Overpopulation of flatulent dinosaurs.

Answer 10

Stick to the liberal credo: When you don't know, it is Bush's fault. Extinct dinosaurs. Bush's fault. My patriots lost, and that's Bush's fault. I have a cold, and I blame Bush for that. And thanks to Bush, I have to work in the morning.

Oh, and I don't believe in the whole global warming c**p, but one thing I do know, if it's true, the liberals know who to blame.

Answer 11

Seems to me that there are some very informed answera above and addign to them will mean nothing but I am tired of hearing about it all really.  This is nothing more than a political debate or a witch hunt similiar to the on Galaleo went through for saying the Earth was round and not the center of the Solar System.  People (politicians/scientist) are making a fortune trying to prove something that we have no more control of then the tide or the rotation of the earth.  All you have to see is that people keep saying CO2 is too high trees are dying. This makes no sence to me because trees absord CO2 last time I checked. Trees are doing just fine and if cars were so dangerous to trees then how come all the trees that align all the roads everywhere are not dead? The fact that they are not all dead makes that argument dead.  People also talk about melting ice in the polar areas.  Well during the summer some will melt remember the ice burg that sank the titanic.  That iceburg had to come from someplace and no one was screaming about global warming then.

This is nothing more than a way to control everyday lives through taxes and the stupid people are willing to give their lives over to an un-elected UN beurocracies which seems silly to me.  SUVs and cars are not the enemy. Cars are what allow us to be free to chose where we go when we want to and live where we want to making cities less densly populated.  

HOGWASH all of it.

Answer 12

I have the same question, they had less fossil fuels... pollution &c. back then... hmmm? I do think we will have another ice age, it maybe one like that of the 1700's, yet could be less... this winter has been very cold in many states, countries, yet, depends on where you are. Last summer, the southeast was in drought, while this winter the midwest has been thrown into a wintry frenzy, who knows anymore? I am from NYC, this winter, luckily it all fell in New England.