The Next Ice Age

[Butcho22]

Let me just preface this by saying I don't know much about this particular issue.

When I was watching 'An Inconvienant Truth' I managed to stay awake long enough to catch a few graphs here and there.

The one I would like to talk about is the one where he shows the average temp. for the earth for it's entire lifespan up to this point. (The one where he get up on a chair or whatever to show where we are headed, etc.)

I'm sorry I couldn't find a link/graph but I hope most of you know what I'm talking about.

If they showed this graph to me and asked me what the next (x) amount of years would be like based on this graph, I would most certainly say we are about to have another ice age.

Again, this is based soley on the way the graph looks. It seemed like once we reached a certain point the earth was like, "nope, here come the freeze." Almost like it was healing itself from getting too hot.

Is there ANY chance we are going to see an ice age within the next 30-100 years?

Again, this isn't my cup of tea but I'm interested to hear from some who may know.

Thanks

[Jiggymike]

Did you look at the X-axis of the graph? It was probably over tens of thousands to millions of years. It is possible that temperatures may drop since they are so high at the moment but there will not be an 'ice age' per se. Frankly I would expect temps. to continue to rise in the near future, at least for anyone who is old enough to post heres lifespan.

[Butcho22]

Yes it was for tens of thousand of years and that is even more of a reason I was thinking an ice age may be likely within the near-ish future.

The graph was to me, shockingly consistent over that big of a sample size.

If we weren't to have a a significant drop in temp. in the near future, it would certainly be going against the trends. I suppose it's tough to call when adding in the human element.

[prohornblower]

IIRC, Ice ages happen roughly every 100,000 years, and the last one was like over 10,000 years ago so I think we're safe for a while.

I saw a great program on ice ages a month ago and perused Wiki for a while. My numbers may be wrong but the ages definitely occur in cycles.

I wouldn't go so far as to say that the Earth is healing itself of it's own volition, but maybe. Nobody really knows what causes ice ages, but there was one like 100 million years ago where almost the entire Earth was frozen. Everywhere but around the equator. A lot of it has to do with the ability for the warm tropical waters to reach teh poles.

If you look at the North pole you can see that, while it isn't landlocked, it isn't very easy for tropical waters to flow up there to warm things down.

[mvdgaag]

I've read an article in the scientific american last year or so (I can look it up if you want to) that showed the same graphs. We are manually keeping the ice age away with our greenhouse effect /images/graemlins/smile.gif

[prohornblower]

IIRC, the average temperature of the Earth drops by like 9d C over a period of a couple years.

Honestly I think it would be really cool if, when I'm like 88 years old, another ice age began. I'd love to see that crazy stuff. Forget Haley's comet. Give me ICE!

[Butcho22]

[ QUOTE ]
I've read an article in the scientific american last year or so (I can look it up if you want to) that showed the same graphs. We are manually keeping the ice age away with our greenhouse effect /images/graemlins/smile.gif

[/ QUOTE ]

thanks for all the replies guys....

Okay, just a thought,

Is it possible the next ice age could come SOONER because of what we're doing to the earth?

Make sense on any level?

[mjkidd]

Yeah man, I saw the movie. When will we listen to Dennis Quaid? WHEN?!?!?!?

[Silent A]

[ QUOTE ]
Is it possible the next ice age could come SOONER because of what we're doing to the earth?

[/ QUOTE ]

There is one theory. First, some background ...

There is a large scale ocean current going from the N Atlatic, to teh S Atlantic, over to the S Indian, then the S Pacific, to the N Pacific, to the N Indian, and back to the S atlantic and then to the N Atlantic. The whole thing is driven by density variations due to differences in salt concentration and water temperature in the N Atlantic. This "thermo-haline" current is a major contributor to heat movement from the equators to the poles.

The theory goes like this:

Global warming causes the polar ice caps start to melt sending lots of fresh water into the Atlantic. This shuts down the thermo-haline current resulting in a significant drop in heat supply to the Artic. This effect is more powerful than global warming and the poles now start to cool. As the poles cool the ice cover returns, reflecting more solar radiation back to space. This causes even more cooling, resulting in a positive feedback that pushes us into an ice age.

Key point: the thermo-haline current is much easier to shut down than to resart, so you can't count on the current to start up again when the cooling starts.

[wacki]

[ QUOTE ]
Is there ANY chance we are going to see an ice age within the next 30-100 years?

[/ QUOTE ]

No. Well, lets just say that you are far more likely to get killed by an asteroid than see an ice age.

Technical jargon:

Ice ages are caused, in part, by Dansgaard-Oeschger (DO) events. During the entire holocene there hasn't been a single DO event. If they were still occurring we'd be recovering from an ice age right about now. That ice age never occurred.

[Silent A]

I should point out that the latest computer models predict this current to weaken, but not stop. This effect offsets some of the expected warming, especially in Northern Europe, but the net effect is still increased temperatures in the Northern hemisphere.

You really need the circulation to completely shut down to get massive cooling, and this is concentrated in the Northern Hemisphere.

This pic is a bit old (2000) and shows changes in temperature (in deg C) 30 years after the circulation shuts down:

http://www.cru.uea.ac.uk/cru/info/thc/thcvellinga.gif

This image does not include any greenhouse effect. So global warming + a complete shut down might still result in warmer land surface temperatures (since most of the severe cooling is limited to the oceans).

[Butcho22]

Thanks for taking the time guys, some good info there.

[CORed]

There are some climatologists who say we would already be in the beginning of an ice age if not for human induced changes. One hypotheses holds that humanity has had a warming influence on the climate for several thousand years, with the preindustrial effect a result of deforestation and rice growing. Rice paddies generate a lot of methane. Humans have cut down and burned a lot of trees, to make room for farms, and for fuel and wood, even before the industrial era.