What caused previous ice ages to occur?

Question

I mean with global warming on the news front, it is said polar ice caps are melting and in turn will cause colder winters. Is this the earths way of controlling the population? Populations rise bringing a rise in green house gases causing global warming, causing a deep freeze, populations die off. Sounds like a natural occurence to me. What do you think?

Answer 1

Climate scientists have all kinds of ideas, but the plain fact is they just don't really know for sure what causes ice ages or why they end. That is why people like me take predictions of future climate changes with a grain of salt, which is to say, with some skepticism, although not outright disbelief.

Answer 2

As Keith P noted, the Milankovitch cycles are one possible theory that explain the glacial/interglacial cycle. However, there are many problems with this particular theory--mainly that the small variations require huge (and unlikely) feedbacks and the periodicity of the Milankovitch cycle does not always match that of previous glacials/interglacials (which is a big problem).

Another possible theory is actual changes in the magnetic activity of the sun:

http://www.unisci.com/stories/20022/0606...

This is a relatively new theory, and obviously, requires more research.

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Edit:

Bob wrote

"Solar radiation has been decreasing while temperatures increase."

Come one Bob, that is only if you use one dataset out of the two main dataets (there are more). ACRIM has shown a slight increase in solar activity.

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Edit2:

"Some folks think having the Antarctic plate at the south pole is important."

There is general agreement that landmass at the south pole makes it easier for ice ages to occur (different than a glacial), but it does not cause ice ages.

Answer 3

Vast civilizations sending smoke signals. Their fires caused a major increase in CO2 and started the whole thing.

It is natural.

Answer 4

penguins, its always the penguins fault

Answer 5

a long winded speech from al gore

Answer 6

Ice ages, and inter-glacial periods, are triggered by small changes in Earth's orbit called Milankovitch cycles (by astronomers) or "orbital forcing" by climatologists.

Since Earth's orbit can be computed for thousands of years into the past and future, we know that orbital forcing peaked 6000 years ago, during the Holocene Maximum, and has been cooling the planet ever since then.

Here's the science:

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

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

Answer 7

ice ages can be caused byt the sun being very quiet for a long time eg. the little ice age or the gulf stream shutting  down as for AGW check this out http://www.dailytech.com/Myth+of+Consens...

Answer 8

I agree with Going Cranky.  Years ago when there were no cars, trucks, industries, pollution etc.  the earth was much much hotter than the environmentalists are predicting will happen and putting all the blame on us.  Same with ice age, we can't control what will happen or not.

Answer 9

Changes in reflectivity may be involved in several periods of declining world temperatures. This has often been the result of extraordinary volcanic activity, increasing reflectivity, or long periods with low volcanic activity, dust settling out, for reduced reflectivity.

But when we have a cooling period it does not consistently result in a major ice age. By that I mean that we do not consistently see many metres of sea water moved up onto the northern land mass as glaciers.

Sometimes the dimming is short lived.

But is the longer lived nature an explanation for the amount of ice built up? or might it be partly that the oceans had not been warm enough to evaporate that water so that it can fly north.

A reason to suspect the hypothesis that oceans must first warm up might be that we have evidence that the earth did have a long major warming period before the last major ice age. This could be concluding causality from sequence of events.

But having oceans warm enough to sustain evaporation at the same time as cloud cover is cooling the earth would at least appear to suggest that the evaporation of the oceans could sustain the cloud cover and support buildup of snow, further producing a cooling effect from reflectivity.

Having a major cooling event like a lot of volcanic activity would explain a cooling but not necessarily evaporation of many metres of sea water.

If you look at the amount of snow falling these days on Antarctica, you have to know that the reason for this  has to do with large volumes of water vapor over the southern oceans. It appears that having large snowfall may be mostly a marker for warm oceans, not necessarily colder temperatures of the air.

Answer 10

no, your not. Also, scientist believe that when the dinosaurs died it was caused by an meteor hitting the earth. It caused dirt, and dust, and stuff to stay in the air causing an ice age which caused the ice age. Also, ice melted because of volcanos. Then, because of the ash ice came back. So, i think that when yellowstone blows then we'll be in an ice age. Here's what's going to happen: Magma will cover the U.S. there will be ash that goes all the way on the other side of the world to Australia. So, we all die from starvation because no food will be able to grow causing the animals to die causing us to die. Unless you like spam!

Answer 11

yes the earth has had many of iceages , some mini and went through warm/cool trends, without man , and with man living on earth.

it is a natural accurance and man has nothing to do with it,nore will we ever,nore can we stop or as some people think slow it down

Answer 12

It is a certainty that this 'climate change' is normal and repeated throughout the Earth's history.  As to what causes it, the primary factors seem to be fluctuations in solar energy output, sunspots, volcanic activity on Earth and under its surface as well as the Earth's eccentric orbit and our solar system's position within the Milky Way.  Lots of factors.

The last Ice Age ended about18,000 years ago and the oceans have risen hundreds of feet since then.  The glaciers have retreated over a thousand miles. Life loves a greenhouse so let's make the most of this warm period.

Answer 13

man can not control weather

Answer 14

Variations in solar radiation due to changes called "Milankovic cycles" (Google it).

How do we know that's not going on now?  Simple, we measure the Sun.  Solar radiation has been decreasing while temperatures increase.

"Recent oppositely directed trends in solar

climate forcings and the global mean surface

air temperature", Lockwood and Frolich (2007), Proc. R. Soc. A

doi:10.1098/rspa.2007.1880

http://www.pubs.royalsoc.ac.uk/media/pro...

News article at:

http://news.bbc.co.uk/1/hi/uk/6290228.st...

Any cold caused by global warming for the forseeable future will simply be local cold due to changes in ocean currents.  Not anything like a "deep freeze".

Answer 15

Boy! I'm glad there weren't any climatologist around back then. It would have been simply called weather.

Answer 16

From all the answers here, it appears possible that an Ice Age occurs when many contributing factors intersect at the same point in time.

All the answers have verifiable science behind their responses.  I commend them all.

I also notice there aren't any lunatics screaming, "It's because of CO2!"

Except for the Penguins.  That is just Penguin hate speech, pure and simple.  Whenever people need a scapegoat, they always try to blame the penguins.

Answer 17

It really doesn't matter whether you believe climate change is caused by greenhouse gases or a natural occurence. The result will be the same.  Scientists are not really sure of the end result of Global Warming, other than catastrophic weather patterns. It is believed that the warming will cause atmospheric changes that will lead to colder temperatures throughout the globe.

They are not only saying that the polar ice caps are melting, they predict that ships will be able to sail unimpeded by ice around the North Pole very soon.  

It doesn't matter to me whether Global Warming is caused by carbon fuels or whether it is a natural event.  Either way, it is frightening to contemplate.  However, since a majority of scientists believe it is caused by greenhouse gases, it only makes sense to try to reduce them.  In the first place, we need to get away from reliance on the Middle East.  In the second place, alternative, cleaner fuels are sorely needed.  

Al Gore believes in Global Warming and has become the spokesman for these scientific groups.  He is a steady, honest, intelligent and admirable man. The contempt ladled upon him by indoctrinated Party Liners, spokesmen one and all for the destruction of independent liberal thought in this country, is contemptible.  They cannot abide anyone disagreeing with their opinions, not even those with scientific expertise.

Global Warming may well not only "control" the population, but endanger it completely.  Thus, it might be imperative that we act on reducing carbon emissions, right or wrong.  Either way, we come out ahead with the use of Alternative Fuels and a cleaner atmosphere.

Answer 18

haha. well earth doesn't care what the population is. It's just matter and so are we.

Answer 19

Lack of solar sun spots, just as increase in solar sun spots increases world temperatures, not CO2.

Answer 20

First you have to know that an Ice-age is a major event of which the Earth has experienced as few as four times in its 4.6 billion year histroy. Any Ice in Polar Regions is considered an ice age. We are in an ice-age, but we're in an interglacial period. Which means the glaciation is minimal right now, but will spread out again.

As for the cause of glaciation, and glacial retreat, there are a number of factors. Almost everything is hypothesized to impact these events.

Ocean currents are considered the most significant functioning element. But the rate at which Glaciation and glacial retreat happen may be linked to Earths orbital cycles.

Either way, the fact that we have continents or ice (land locked arctic ocean) blocking both poles causes ocean currents to not warm the Earth evenly, and this is what causes the current large scale ice age. The only thing stopping us from being a constant 'snowball Earth' based on our current continental configuration is the negative feedback caused by direct sunlight melting ice.

Right now the Earth wants to cool because the Ocean currents cant flow over the poles to warm the Earth evenly. So glaciers begin to grow. As they grow, they aid themselves by reflect sunlight, leading to cooler temperatures and more growth. But as the glaciers grow to a certain point, they reduce weathering of Earth Significantly. Eventually the clouds (and water vapor in general) are removed. Thus more direct sunlights hits snow. This leads to melting snow, which leads to higher water vapor, which leads to warmer temperatures because of a green house effect. Eventually the the glaciers retreat, but the Earth cant stay warm because of the blocked ocean currents at the poles.

It is noted that this process doesnt get set in motion without some influence. I describe the pendulum going back and forth, but now how its set in motion. Those influences are widely debated. Certainly the wobble of Earths orbit (the Earth not only spins and rotates, but wobbles on its axis like a person in a hoola-hoop) are a agent for change.

Answer 21

Some folks think having the Antarctic plate at the south  pole is important.

Otherwise no one has come up with a good theory.  Lots of interesting possibilities but nothing coming close to something that explains anything.

Answer 22

s.u.v.'s caused all the ice ages.

that and....um.... incandescent light bulbs.

oh- and coal fired electric plants.

Answer 23

Cave men drove SUVs.

Answer 24

To give an exact answer to your question we are still in an ice age. Ice ages occur roughly every 200 million years. During the present ice age there have been roughly 20 interglacial periods. Seventy million years ago the Earth was much warmer and tropical conditions extended much further North and South than currently, it is not known what causes ice ages.

http://www.pbs.org/wgbh/nova/ice/chill.h...

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