OK, this may be a stupid question, but how can Global Warming lead to another Ice Age?

Question

If Global Warming is melting all of the ice caps in and around the polar regions, then how can this possibly lead to an Ice Age?

Answer 1

The melting of glaciers will add massive amounts of fresh water to the ocean which may disrupt the balance of salinity that drives the thermohaline conveyor. The conveyor is the system of ocean currents that is responsible for the warmer climate of Northern Europe as compared to other locations at the same latitute. This is what happened during the time period known as the "little ice age."

Here are a couple of articles for you:
http://yaleglobal.yale.edu/display.article?id=2798
http://www.ncdc.noaa.gov/paleo/abrupt/story3.html

Answer 2

Doesn't sound stupid, if you don't ask you don't learn.

The possibility of global warming leading to another 'ice age' is not a theory that is widely supported within the scientific community. More than anything it's the result of sensationalistic media reporting.

It is possible that some places may be plunged into a mini ice age, it's unlikely and it's not something that is well understood. Here's the scenario...

Global warming is causing the ice caps to melt, most melting is occurring from the Arctic Ice Cap - approx 600 billion tons last year and a further 220 billion tons from the Greenland Ice Cap (Antarctica is pretty stable at the moment).

This meltwater runs off the ice caps and into the surrounding seas and oceans. Because it's fresh water it's temperature is just above freezing point, the seas around the ice caps are actually just below freezing point because they're salt water which has a lower freezing point than freshwater. So the first thing it does is to warm the surrounding waters slightly. Now, most things when they warm up expand but water has an unusual property in that it contracts when it's less then 4°C.

So we've got this weird situation where meltwater is warming the seas and at the same time causing them to contract. This contraction is more than offset by the additional water but it does mean that the increase in volume of the seas is smaller than the volume of water entering them.

The point that is causing some concern is that the burden of meltwater may interupt the North Atlantic Conveyor, also called the Gulf Stream. This is an ocean current which transports warm waters from the Carribean across the Atlantic Ocean and delivers them to the shores of the UK, Ireland, Iceland and to a lesser extend parts of the European coast.

The primary driver of weather in these countries is the Atlantic Ocean - the prevailing winds are south-westerly and come in off the Atlantic. Because of the heat carried by the Gulf Stream the climate of these countries is about 7°C warmer than it would otherwise be.

If the Gulf Stream were to be affected by the meltwater it could do one of several things - it could divert and transport the warmer waters elsewhere, it could truncate and stop somewhere in the middle of the Atlantic or it could effectively be switched off. In any of these scenarios the warming benefit it brings to parts of northern Europe would be lost and temperatures there would fall by up to 7°C.

This would mean an advance of glaciers in the Scandinavian countries and the partial glaciation of some parts of Scotland. As such it wouldn't be an ice age in the true sense of the world and would only affect a relatively small area.

The Gulf Stream is one part of a much larger system of ocean currents called the Tehrmohaline Circulation or Meridian Overturning Circulation. Essentially these conveyors move warmer waters away from the equator, the warmer waters travelling close to the surface of the seas and oceans. When they reach their destination they 'overturn' and cold water is returned at a greater depth in the oceans.

If part of the thermohaline circulation were switched off or truncated it would not affect the rest of the conveyors. The outflowing warm waters and the inflowing cold waters are in equilibrium and for all intents and purposes each conveyor acts as an entity in it's own right.

As I mentioned earlier, this isn't something that is particularly well understood so for the time being the best anyone can do is to make educated guesses as to what may happen.

There's much more to it than that but I hope this gives you something to go on.

Answer 3

It's not a stupid question at all. The idea refers to a hypothesis abot one of the possible consequences of prolonged global warming.

Here, breifly, is the hypothesis:

As the Earth warms, the Greenland ice cap wll pour a lot of fresh water into the North Atlantic. This changes the salinity (amount of salt) in seawater, and its densit and temperature. The effect of this would (if the hypothesis is correct) to cause the Gulf Stream to change its course.

The Gulf Stream is the warm-water current that flows north along the Eastern Seaboartd of North America, across the Atlantic, and then south along the European coast. The warm water keeps the climate in those areas warm. So--if it moves, the climate will get colder. That--if its severe enough, could cause enough cooling to start glaciers forming in eastern Canada--perhaps as far south as New Englad--and in Britain and northwestern Europe. Eventually that could lead to a mini "Ice Age" in those areas.

So--ironically, even though the Earth as a whole would still be warmer, we'd have a region that would be much colder.

And--we are seeing a similar effect already in Antartica. The mechanism for this isn't fully understood yet (thats sceientist-speak for they haven't figured how how this works yet)--but although the coastal areas of Antartica are warmer (in fact, they've warmed more than any other area of Earth at this point) the deep interior of the continent near the South Pole is actually a little colder.

Answer 4

back in the 1970's one man (Lowell Ponte) published one book ("The Cooling") suggesting this might be possible. He was a weather analyst for the CIA (not a climatologist. He had his 15 minutes of fame. And the goofballs now like to claim the scientific community predicted an ice age. Anyway...

The idea is as it warms up, more water evaporates at the equator, and more snow falls at the poles. As this happens and increases, the ice caps expand, and their greater area reflects more of the suns energy back into space. There's a similar theory called "Snow Ball Earth" that says the ice caps could expand until all of the incoming energy was reflected out, and the ice age would become permanent.

Observed data does not match either theory, and neither idea ever had any wide acceptance (outside the popular press, at least).

Answer 5

Certainly not a stupid question! There is conciderable debate about global warming because the causes are many and the impacts are so complex. Too many people focus on one aspect only and don't see (or want to see) the interrelationship of the entire system. This would take me a book to write!
There are several complex mechanisms for heat transfer in the environment. Let's take one - the Gulf Stream. This current of warm salt water keeps Europe and England especially, warmer than it would be without it. As global warming continues, the polar caps melt and pour fresh water into the ocean. Fresh water is less dense than salt water so the fresh water creates a cover. When the Gulf Stream reaches Europe, it will not be able to warm the area as effectivly. Cooler temperatures will become the norm. Additionally, when the fresh cold water cools the warm salt water, there will be a disruption of the conveyer. The currents will basically shut down. This will lead to many areas that are bathed on the warm Gulf water being cooler than before. There is some evedence that this has happended before but people were not around to notice it.

There are many examples of the individual effects like this. Cloud cover from increased evaporation, reduction of the reflective surface of the ice allowing more heat to be absorbed by the earth and water, ...The problem is that we don't have an understanding of how they are all related. We're working on it and what we can see looks scary.

One problem is that people (like one of your other answerers) only look at this year and last year. Climate change happens all the time but on a scale that we can barely understand. At one time Egypt was the grain basket of the Roman Empire. Climate change in the area of central Africa eliminated the rains that caused monsoon like effects in Northern Africa. . That caused a massive retention of heat in northern Africa, disruption (elimination) of the normal rainfall, and caused plants to die. Without plants absorbing the sunlight more heat was generated and deserts started to form.

The Discovery Channel has had a few good programs explaining some of the isolated effects.

Answer 6

It won't, in the sense of previous ice ages.

It may disrupt ocean currents (theoretical possibility that hasn't shown up yet) which would cause local areas to cool, not a true ice age. One such local area is Europe, which is kinda important, but scientists currently think the most that would happen is that Europe would warm less.

True global ice ages occur at approximately 100,000 year intervals, because of orbital changes with the Earth and the Sun. The next one isn't due for about 75,000 years.

Answer 7

In order for a true ice age to occur, it is required that temperatures in the summer drop to such low levels that it effectively remains winter all year round. Snow that falls in the winter therefore never does melt, but rather continues to accumulate, and the end result is an 'ice age', and the creation of ice sheets as much as two miles thick, the result of annual accumulation of snow cover over many centuries. Ice Ages follow a pattern which is established by variations in the patterns of the Earth's Orbit around the sun and variations in the earth's tilt and rotation. The Earth does not follow a perfectly circular orbit, but rather it follows an eccentric elliptical orbit, with a cycle of one hundred thousand years. The amount of sun light reaching the earth varies depending on how extreme the distance of the earth is at the maximum of the elliptic as well as the variation of distance during each season. The earth also wobbles as it spins, up to 23.5 degrees, a cycle which takes 41,000 years. This wobble also causes the position of the earth in its elliptical orbit to change, a phenemona known as the precession of equinoxes, which follows a cycle of 23,000 years. Ice Ages occur when all three of these factors are in favorable alignment resulting in the least amount of summer warmth in the Northern hemisphere when summer occurs at the farthest point in the Earth's elliptical orbit. Summer temperatures therefore plunge to winter like conditions, and snow accumulates from year to year rather than melting. Similarly, the ice age ends when the process is the opposite, resulting in increased summer heat, and summers which take place at the closest point in the elliptical orbit.

Answer 8

The simplest model is this:
Global temps rise, more water evaporates causing more cloud cover, more cloud cover reflects solar heat, global temp drops, we have an ice age.
It would only take a few years of 100% cloud cover to drop global temps enough to trigger an ice age. By then most crops would have failed, we would have widespread famine and wars and, oh, yes, no more cheap, easy to find petroleum.
We may survive global warming, I don't think we have what it takes to survive an ice age.

Answer 9

I have heard that some computer models show that. It just goes to show you how unreliable the models are. The result of all this CO2 could be anything from melting all the polar ice to another ice age, depending on which model you use.

Answer 10

This is the great thing about "global warming". It caused the climate to heat up, and cool down. It causes floods and droughts. More snow, less snow, more hurricanes, fewer hurricanes, yep, it's "global warming" that caused it.

We're even blaming volcano's and tsunamis on global warming.

Because of these "facts", we know that global warming is here and we have to deal with it every day. Now it's just asking congress to raise taxes.