Geology and Earth ScienceIce Ages by Joe Leddy
Ice Ages
Hollywood has developed an image of an Ice Age that is catastrophic and in the case of the movie "The Day After Tomorrow" sudden. There are many questions to be studied in order to understand what an Ice Age is. What exactly is an Ice Age? How are they caused? Are there Ice Age Cycles? And can global warming cause an Ice Age?
You can define an Ice Age as a period of a long-term downturn in the temperature of the Earths Climate, resulting in the expansion/growth of continental ice sheets/polar ice sheets, and the growth of mountain glaciers (taken from Wikipedia.com) this is also known as glaciation. It should be noted that you could still be in an Ice Age if the Glaciers are retreating; you are just in the process of coming out of the Ice Age. The term Glacial Periods refers to the colder period of the Ice Age and Interglacial refers to the warmer periods. (We are technically in an interglacial period following a retreat of ice roughly
10,000 years ago)
There are three generally accepted factors that cause
Ice Ages:
- Atmospheric Composition - Carbon Dioxide and Methane
being the chief gases of concern (Decreases in
concentrations within the atmosphere) - Variations in the Earths orbit around the Sun (This
is known as the Milankovitch Theory - The Earth
wobbles as it orbits the Sun and it takes
approximately 41,000 years to complete one wobble.
The wobble is roughly 22 degrees. This tilt of the
Earth is the cause of our seasons. If the tilt
varies, say to 25 degrees, we could in theory have
dramatic shifts in our climate) - The Arrangement of the continents places a part as
well. If there are landmasses near the poles there is
a place for the ice to build.
Ice Ages do appear to come and go in a cycle. They generally occur at 100,000-year frequencies however they have been known to occur every 40,000 years. Geologists know the time line by the scrapes the ice leaves behind in the rock. This pattern has held for the last few million years. Within this time there has been 4 major Ice Ages.
The earliest is theorized to have taken place between 2.7 and 2.3 billion years ago, this would have placed it in the early Proterozoic Age. Next comes the Snowball Earth Ice Age, this took place 800 to 600 million years ago. It is referred to as Snowball Earth because permanent sea ice extended to or quite close to the equator. This Ice Age would have taken place in the Cryogenian period.
Roughly 460 to 430 million years ago, during the Late Ordovician Period, another one occurred. And finally there were quite extensive polar ice caps 350 to 260 million years ago during the Carboniferous and Early Permian Periods.
The last Ice Age began 40 million years ago and intensified during the Pleistocene with ice sheets spreading in the Northern Hemisphere. The last glacial period of this Ice Age ended roughly 10,000 years ago.
As you can see, if Ice Ages occur every 40,000 to 100,000 years, it is the mini ice age that is far more common than the major Day After Tomorrow types we see in the movies.
It is not global warming that causes the Ice Ages, rather the removal of Carbon Dioxide from the atmosphere. Global warming can indirectly affect this however. In theory, if the greenhouse effect melts the Ice caps the ocean currents could be drastically affected. If the currents are changed the blooming of plankton (photosynthetic organisms) can also be affected. If the bloom is too large, the process of photosynthesis (the conversion of Carbon Dioxide into Oxygen) canremove massive levels of CO2 from the atmosphere. It is that removal that has scientists concerned about another Ice Age. (Please keep in mind this is an over simplified explanation of a very complex process)
For more information please see the following:
Discover Magazine September 2002 - A New Ice Age:
The Day After Tomorrow
www.discover.com
www.ncdc.noaa.gov/paleo/glaciation.html
www.wikipedia.com
Or speak with or review Professor Mandias Website
9 Comments:
Global warming does much damage to our planet, and the decrease of o-zone gases is of major concern. We could either freeze, due to an early Ice Age brought on by atmospheric changes, or we could heat up our planet so much because of the lose of our protective o-zone layer that drastic climate changes will either force us to adapt or kill us.
Given that we are creative of change and can adapt when necessary, I’m estimating that a good number of human beings could survive an Ice Age if one came around. Yet at the same time, most human beings seem unwilling to adapt, wishing that our earth could stay the same, and is there a way to change or alter the damage we’ve already done. That, though, is not the biggest worry. Sure we can change our ways, shut down our factories, stop polluting and learn to recycle - but we can’t change the fact that if an Ice Age is meant to happen, it’s going to happen.
Considering it takes time for an Ice Age to become full blown, we could learn to adapt as it happens. If Alaska and much of Canada can survive glaciers and lots and lots of snow, I’m pretty sure the rest of the world can.
What worries me about global warming and the melting of polar ice caps is that they are melting. Wouldn’t this cause the seas to rise, resulting in transgressions over time a long (or short) period of time? Most of the land masses could end up under water, instead of covered in ice, if this was true.
The earth though, does Ice Ages in cycles, and we could be due for one in the coming years. I agree with the author that a major one, like in the movie The Day After Tomorrow, will probably not happen, at least not something that catastrophic or sudden. I do believe that we could bring on an Ice Age at a sooner time, considering how often we take advantage of our planet.
Also, Ice Ages tend to happen when the continents are clustered together, like Pangaea, because the water absorbs sunlight, while land masses reflect it. When the continents are land-locked, they have no way of absorbing that warmth, and so we get Ice Ages, for example, Snow Ball Earth.
With the ridges and trenches that exist on our continent, such as the Mid-Atlantic ridge, it would be possible that in a thousand years or so, the continents could be lined up again in such a way, bringing on an Ice Age. With the added fact of global warming, we could likely see it happen sooner than that, but it’s only a possibility. I do believe that we are building up to another Ice Age, if not now, then sometime soon.
Are you telling me that there were not a bunch of talking animals that saved a Native American baby, does Disney know this!!! It is always interesting to me when I hear people blow off the global warming theory with such disbelief. My friends mother knows nothing about it but rants at the "liberals" (as she calls them) talking such nonsense. Global warming, they are so stupid she says, such nonsense I can't stand it! She says all this while she smokes her cigarettes, that don't cause cancer by the way. All this from a highly intelligent woman. I read Alli's comments and I agree with him that there needs to be change. But how can we propose change when there are people who believe an ice age could appear, our atmosphere is being destroyed, our water is polluted, and all the other things we do to our planet is just propaganda. The problem with science is that sometimes it is to difficult for a novice to understand or even conceive. Katrina is a perfect example of this. We have a whole population of people who are underprivileged in everyway. They have low incomes; they have a lack of education, and lack of resources. How could we expect everyone to come aboard and help with a situation as complex as preventing an ice age when most people cant prepare or escape a hurricane? When alli said that most people could survive an ice age I have to disagree and say most would die. We would be left in chaos. There needs to be a simpler way to explain this to the commoner with less jargon if we want to get anywhere with trying to keep us from natural disasters
I was particularly interested in the last part of this article. I believe that it’s quite possible we might have another ice age if we do not start taking care of out planet. About 20% of the world’s human population, which live in the rich industrialized nations, consume about 80% of its resources. They are also responsible for most of the global pollution and greenhouse warming. While people in these nations are enjoying the fruits of their modern life style, the poorer nations are rushing to develop their share. This will dramatically increase the release of greenhouse gases and other pollutants into the atmosphere and cause global warm temperatures to rise considerably. Such increases in global temperatures would substantially change the face of the planet. We certainly wouldn’t survive.
Ice Ages have dramatically affected the life of Earth almost from the very beginning. It is even possible that life itself significantly changed the climate. All living things pull carbon dioxide out of the atmosphere and eventually store it in sedimentary rocks within the Earth’s crust. If too much carbon dioxide is lost, too much heat escapes out into the atmosphere. This can cause the Earth to cool enough for glacial ice to spread across the land.
In general the reduction of the levels of carbon dioxide in the atmosphere has been equalized by the output of carbon dioxide from such events as large volcanic eruptions. Man, however is upsetting the equation by burning fossil fuels and destroying tropical rain forests, both of which release stored carbon dioxide. This increases the greenhouse effect and causes the earth to warm. If the warming is significant enough, the polar ice caps will eventually melt.
The continued melting of the great icebergs in the polar regions because of higher ocean temperatures and rising sea levels could cause massive amounts of ice to crash into the ocean. This would further raise the sea level and release more ice, which could more than double the area of ice in the sea and increase correspondingly the amount of sunlight reflected back into space. The ice would chill the waters in the ocean and ocean currents would move the cold water all over the world. The drop in ocean temperature could dramatically change the path of ocean currents and disrupt weather patterns significantly. The cycle would then be complete as this could cause global temperatures to drop enough to initiate another ice age. The next ice age is long overdue. Its onset depends on how man alters the climate by adding to the greenhouse effect.
I hear this stuff everyday on some stupid tv commercial ... or so like save the planet type stuff . Before any of this stuff takes place , were gunna be dead . So lets not worry about how big of a problem its going to be . The earth as we have seen has a way of "reseting" it self . I think it will do this when t ozone gets really bad . i know this might sound stupid to alot or you but , you have to take in conisderation that ive taken this class twice ! Well actualy once , the first time i slept threw it ( sorry sean ) , anyway , as for the whole ice age thing . I don think it will be as of a drazitc force like we see in the movie . maybe were entering one right now and dont even know it . Like every geological event in history , its going to take millions of years before we have another snowball earth . An when the contintints come back together like the cyclical change we alway here about , were not going to be able to watch it out of are front window . Who knows what going to happen . Life might reset itself . People like i said before , are worried to death about everytime i use hair spay with aerosals or dont get my car inspected . Sure we do through alot of pollutants into the air . Hears the thing though , if the world can survive a metior the size of mt.everast which killed 60% of everything then im sure it can fix the hole in the atmosphere . Nobodies dying when i start my car ... well that is unless i hit somebody with it . Anyway i dont think we really have anything to worry about . Back in the day the earth suffered way more than what were doing to it . And no were are not going to wake up with half manhatten covered in snow . I will take millions of years and a representive time line for anyone to realize the change that happenes when we embark on this ice age . This is w way of the earth to star over . A it might just lead to a better species of human being . Its in my mind sort of like the world making its own natural selection of everything . Plus the snow mobile market will be awsome !!!!!
We should be worried about the problems we face now , not ones that are going to arize while were taking dirt naps!
Seriously though this cycle has being going on for billions of years at the same time . So why then try to stop it . If we really analye things were only a spec of time in geologic history , so can we reall make that much of a difference in the world ( natural that is ) i honestly dont think so
I am not sure if the article made clear that all three factors were definite causes of ice ages, but if not, I believe that the Milkankovich theory would best fit the cause. Out of the three, it seems to fit with the idea that the ice ages may be cyclical, whereas the Earth’s orbit is cyclical as well. In the article it also states that the Earth’s wobble may take 41,000 years to complete its cycle and that the ice ages each occur anywhere from 40,000-100,000 years. These dates could possibly correspond with each other and that is probably pretty good evidence to look further into, which may support the Milkankovich theory in being the top factor to cause ice ages.
In regards to the cause being global warming, which we, as a planet, are so generously increasing, I don’t believe this will be the main cause. Of course I feel we have certainly aided in the ruination of the O-zone layer, which would have saved us a lot of money on UV protection if left alone, and we have definitely released precious gases like Carbon Dioxide from our atmosphere, but this will not be the downfall. The overuse of Aqua Net and smelly polluting trucks has just speeded up the process. The reality of the problem is just the inevitability of nature itself.
As for a straight opinionated reason why I believe the Milkankovich theory is definitely the cause has to do with my thoughts on cycles in and of themselves. I see this planet as plainly cyclical, excluding biology at times. We are aware that the Earth’s orbit is cyclical yearly, and even daily we watch it happen. As night falls, the Earth gets colder and the same with our tilt throughout the year, this changes our temperature as well. So it seems to me that given large amounts of time the Earth’s position to the sun in our solar system will change such a drastic amount to create an ice age.
I do believe that movies such as The Day After Tomorrow over-dramatize what may occur if this happened during a time of a high human population. They are correct with the idea that there might be mass hysteria, if it had happened to be a speedy catastrophic event, but this would most likely not happen. Most of these huge climatic changes seem to happen very slowly and I would expect something like an ice age to take hundreds of years for temperatures to drop so low and for things to freeze over. Most people probably would die out and I am not so sure that the ones who survived would survive because love is keeping them alive. I think the people who have good instincts and intelligence, and maybe some extra meat on their bones would survive better than the love story.
I actually find it to be amazing that mammals survive at all during periods like this. This makes me wonder why the reptiles and cold blooded species haven’t flourished, instead of man, as a result of the last few ice ages. Wouldn’t they be better off than man would?
The idea of an ice age is something that most people don’t think will happen again. And if they do think it’s going to happen again they have the idea of just a quick freeze over and we’ll never know what happened to us. An ice age will happen again. The records show the cycles of these ice ages. So eventually the cycle will come around again and we will have another ice age on our hands. But as Alli said we are very well adapted. There are also new technologies that come around everyday. If you look at where we are in terms of technology today and then look at where we were fifty years ago you will there are some big changes. So if there were signs showing that we would be having an ice age soon there is no question in my mind that someone would think something up and we would be able to reverse it or at least make a bubble or something over a certain part of the world. Life survived though ice ages before so it will be done again. Global warming is also a problem that I think will happen before we have an ice age. With all the pollution and problems that were having with the ozone layer that is gong to diminish eventually and we will have no protection from the sun. This will cause the world to warm up and the ice caps will melt and the sea levels will rise and there could be a domino effect and it will just be one problem after the other. Now that were on the topic of seas and the oceans we can think back to when we had the ice ages. The continents were one big continent, the ocean was one big ocean. Therefore the land reflected the heat and the oceans absorbed the heat. Because there was no water circulating on the inside of the land it wasn’t bringing heat to the center. Therefore it got colder and colder and when it snowed the ice didn’t melt and created a glacier. If the continents ever slam back into each other the whole thing would start all over again. Then again by the time another ice age happens we may have learned to settle on other planets.
From Anthony Angione
In movies like “The Day After Tomorrow” a sudden ice age occurred. It wiped out half of the planet. Could it happen again. A group of British scientists I was told said it was possible. Could we really be that vulnerable. The Dinosaurs went extinct in a matter of seconds most likely. Could it happen to us in the sudden form of an ice age. People don’t think it could happen ever again. Earth goes in cycles. Like history it repeats itself over and over again. Shocking isn’t it that we could suddenly plunder into another ice age. We could suddenly be living on a place that is 90% ice. However we are the smartest things ever developed on this planet. We can certainly think of ways of survival. Human ingenuity is a strange thing. We don’t use it until we need it. We could need it here. We don’t have to wind up like the dinosaurs. We can use our skills and put them to good use. All the Global warming and pollution assures us that we will make it come faster than we think. The polar ice caps melting will also help wreck out planet. The earth is 75% water. If it becomes frozen we can use it till live on. If signs are showing that the end of what we think of as civilization is coming we should start putting our hands and minds to good use. We need to get down and dirty and stop polluting up world, our planet. If we don’t we may not be ready for this thing coming. Mankind must be careful. We are wrecking our planet and the unthinkable will happen if we do not stop. The unthinkable being we will have to live in igloos. So my friends please be careful get ready because the mother of all blizzards and disasters is coming. Just watch the movie “The Day after Tomorrow” and you will see a glimpse of what is coming.
While reading this article I have found that ice ages are more common then any one would have ever expected. As stated they happen about every 40000 to 100000 years in cycles. Also as long as there are glaciers on earth we are in an ice age, it just might be the later part when they are reseeding. This would be a significant difference in the movie Day After Tomorrow when the world freezes nearly over night. As much as I liked that movie I also find it hard to believe that the weather could change that fast and so violently. Although the world we live in is a hazardous place these things still need time to build up and change. Further more if humans survived the last ice as primitive as they were we surly can survive the next one with greater ease. Maybe we can even find a way to counteract it. But then again this might just cause some other problem that would probably be worst then when we started.
The theory of a snowball earth remains a controversy. What is the snowball earth theory? It states that around 600 to 750 million years ago the earth entered an ice age that affected the planet in such a way that it was completely covered in ice from pole to pole! The reason many scientists have and still disagree with this theory is they feel the tropics can’t freeze not now and not then. The tropics receive the full glare of the sun keeping it warm. During the height of the last ice age 10,000 years ago the tropics remained warm so it had been accepted that the tropics has always remained warm. This all changed when scientists started questioning how drop stones appeared in the rock record of the tropics. Drop stones are boulders that get trapped in glaciers and as the glacier melts the boulders drop hence the name drop stone. Some said it proved the tropics have frozen over in the past, others claim it is the result of plate tectonics. Those who believe the latter state that the land that occupies this region was once located in the polar area and that is how it is able to show signs of glacial evidence in the rock record. This debate remained in the background until the 1960’s. During this time scientists in the Soviet Union were doing research on nuclear winter and a Climatologist named Mikhail Budyko compiled studies on the origins of ice ages. He believed that the tropics could freeze over. Do to the fact that the land and oceans are dark they absorb heat and this is how earth is warmed. During an ice age as more light colored ice forms causing some of the solar heat to be reflected away from earth. Mikhail Budyko believed it is possible to develop a tipping point (he even worked it out mathematically) that could cause about fifty percent of the solar heat to be reflected away from the planet and create a snowball earth. Their was only one problem he also believed that once the planet reaches this state it would stay frozen and should still be today. Once again the debate died down until Professor Joseph Kirchvink entered the debate. He originally believed that during the time in question the poles located all the continents and that snowball earth never happened. Kirchvink dedicated much of his career to the study of magnetism he found out about tests done by scientist in Australia that proved dropstones in the tropics were the result of glaciers being present at the tropics and not do to continental drift. Kirchvink decided to test the rock evidence himself. Using his hypersensitive Magnetometer and computers he did confirm that the dropstones were created at the equator and that snowball earth could and did happen. The problem with all of this is that according to earlier study by Mikhail Budyko if the earth experienced a complete freeze it would remain frozen to this day. Budyko overlooked one important detail volcanic activity. Magma is not affected by ice on the surface and volcanic activity was ongoing then as it is now. Volcanoes produce 10 billion tons of gas each year. A large portion of this gas is carbon dioxide. During snowball earth all the water is locked up in the form of ice so it does not rain this allows carbon dioxide levels to rise. Over millions of years this accumulation of carbon dioxide accounted for ten percent of the earths atmosphere, compared to less than one percent today. This led to large scale global warming and the hottest earth ever, with an average temperature of 110 degrees Fahrenheit hot enough to thaw out the frozen earth. More and more evidence has been tested that deals with how life survived this intense ice age and how Tropical rock formations were affected and it does seem quite possible that snowball earth did occur and more than once!
For more information go to http://www.snowballearth.org/overview.html
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