Ocean cooling contributed to mid-20th century global warming hiatus

Sep 22, 2010
David W.J. Thompson, professor of atmospheric science at Colorado State University, is the lead author of a Nature paper that shows sudden ocean cooling contributed to a global warming hiatus in the middle 20th century in the Northern Hemisphere. Credit: Colorado State University

The hiatus of global warming in the Northern Hemisphere during the mid-20th century may have been due to an abrupt cooling event centered over the North Atlantic around 1970, rather than the cooling effects of tropospheric pollution, according to a new paper appearing today in Nature.

David W. J. Thompson, an professor at Colorado State University, is the lead author on the paper. Other authors are John M. Wallace at the University of Washington, and John J. Kennedy at the Met Office and Phil D. Jones of the University of East Anglia, both in the United Kingdom.

The international team of scientists discovered an unexpectedly abrupt cooling event that occurred between roughly 1968 and 1972 in Northern Hemisphere . The research indicates that the cooling played a key role in the different rates of warming seen in the Northern and Southern Hemispheres in the middle 20th century.

"We knew that the Northern Hemisphere oceans cooled during the mid-20th century, but the sudden nature of that cooling surprised us," Thompson said.

While the temperature drop was evident in data from all Northern Hemisphere oceans, it was most pronounced in the northern North Atlantic, a region of the world ocean thought to be climatically dynamic.

"Accounting for the effects of some forms of natural variability - such as and - helped us to identify the suddenness of the event," Jones said.

The different rates of warming in the Northern and Southern Hemispheres in the middle 20th century are frequently attributed to the larger buildup of tropospheric aerosol pollution in the rapidly industrializing Northern Hemisphere. Aerosol pollution contributes to cooling of the Earth's surface and thus can attenuate the warming due to increasing .

But the new paper offers an alternative interpretation of the difference in mid-century temperature trends.

"The suddenness of the drop in Northern Hemisphere ocean temperatures relative to the Southern Hemisphere is difficult to reconcile with the relatively slow buildup of tropospheric aerosols," Thompson said.

"We don't know why the ocean areas cooled so rapidly around 1970. But the cooling appears to be largest in a climatically important region of the ocean," Wallace said.

Explore further: Warm ocean melting East Antarctica's largest glacier

Provided by Colorado State University

4.5 /5 (12 votes)

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3.1 / 5 (16) Sep 22, 2010
So the reason why global-scale warming is so hard to detect in the 20th Century is that its effects were mitigated by concurrent global-scale cooling?


I left adolescence behind me a couple of decades ago, but every time my mother sees me she swears I have grown. Obviously, the only reason I'm not nineteen feet tall is that my runaway post-adolescent growth (confirmed by a consensus of female relatives) is mitigated by the fact that--for some unknown reason--I am also shrinking at exactly the same rate!
2.8 / 5 (12) Sep 22, 2010

It doesn't matter if we are cooling or warming - Global Warming is to blame. You will be assimilated.
4.7 / 5 (12) Sep 22, 2010
As usual, these reports are poorly written. What they are talking about is a change in surface temperature. That can be caused by upwelling or other mechanisms. There is a tremendous amount of heat stored in the oceans. When a current changes the heat moves around. Do you think the ocean actually gets warmer during an el nino? NO. The surface of the ocean gets warmer. In this case the surface of the ocean got colder and they don't know why. In the mean time the GHGs were still trapping heat but it was overridden by the movement of stored heat within the ocean. Anyone who thinks the ocean changes a significant amount of stored energy on an annual time scale is not able to do the math.
4.1 / 5 (8) Sep 22, 2010
What this study does show is that we don't understand as much as we thought we did and much more research is needed. That's not to say that AGW is false, nor is to say it is real. It just means we need a lot more research to fully understand what is going on.
2.2 / 5 (6) Sep 23, 2010
Possibly there was a reduction in volcanic activity along the mid-Atlantic rift during the period?
3 / 5 (4) Sep 23, 2010
Well, this is from SkepticalScience.com, a pro-AGW web site:

"As a final point, it should be noted that in 1945, the way in which sea temperatures were measured changed, leading to a substantial drop in apparent temperatures. Once the data are corrected, it is expected that the cooling trend in the middle of the century will be less pronounced."


Interesting contrast to what is written here. I have not looked for independent verification of what they claim.
1.1 / 5 (7) Sep 23, 2010
Anyone have an estimate for the median ocean temperature? My guess is that it is not much higher than 4 C.
1.7 / 5 (11) Sep 23, 2010
The bottom line with AGW regardless of which side you are on is that the PRO side, at least the scientists approach those who don;t believe in pro-AGW as being too stupid or dumb to know whats good for them and that's NOT how you go about winning folks over to your side of an argument.

Its hard for the pro-AGW crowd to convince most of us that pro-AGW is real because the proposed basis for making this case is a science that is unable to accurately predict weather beyond a few days. When you add to the fact that the solution being put forth is one that will bring about death and economic depression on a Global scale for all but the elite and powerful is it a wonder the masses say BS to pro-AGW?

If you want to convince those of us who don't believe in pro-AWG that it is real then don't call us us weather deniers or too dumb to know whats good for us.
4.6 / 5 (10) Sep 23, 2010
YSLGuru: First, let me point out that your complaint about those of us who have studied AGW and have come to the conclusion it is real face constant derision by a number of the posters here (marjon leads the pack). Specifically, we have been addressed as pinkos, socialists, idiots, stupid, uneducated, Nazis, and other terms of endearment that don't come immediately to mind. In reality, many of us are professional scientists who study specific disciples related to AGW. Multiple times our studious explanations have been answered with a series of repeating questions clearly designed to bait us. We have become fed up with that response and to multiple participants (such as marjon) we just answer his questions and don't respond to his vitriol.
5 / 5 (9) Sep 23, 2010
YSLGuru (continued): However, I would expect some level of self education before someone posts something like you just did. Specifically, you are making the classic error of confusing weather with climate. As you said: "then don't call us us weather deniers." We don't. In fact we wouldn't call you anything if you had an open mind. If you have been watching this blog it would be clear to you that weather modeling and climate modeling are very different tasks. You further say: "because the proposed basis for making this case is a science that is unable to accurately predict weather beyond a few days." Again, hopelessly confusing weather modeling with climate modeling.

On top of that you make the claim: "When you add to the fact that the solution being put forth is one that will bring about death and economic depression on a Global scale for all but the elite and powerful is it a wonder the masses say BS to pro-AGW?" It is clear that you have an agenda based on money. (continued)
1.7 / 5 (12) Sep 23, 2010
One last thought for the pro-AGM crowd especially if you are part of the group that thinks the rest of us are just too dumb to realize pro-AGW is gospel.

My grandfather dropped out of school in the 8th grade and even though he was not an educated man he still had basic common sense. If you tried to convince him that the sky is supposed to be pink with purple clouds and that its not because of man-made pollution he'd still be able to see through your BS.
5 / 5 (9) Sep 23, 2010
YSLGuru: (continued) Your premise that any solution to global warming has to result in economic depression and death is amazingly hysterical. There are many proposed approaches to minimize AGW that save lives and build new industries. Your view that some, unnamed, "elite and powerful" group is going to profit while the rest die in poverty can't even sound reasonable to you, in retrospect. Talk about calling names, you are implying that anyone understanding the potential effects of continued "business as usual" and interested in mitigating the effects is out to kill and bankrupt the middle class. Read your post again. You don't want to be called a denier but it is OK to call those who disagree with you killers and greedy self-interested elite.

If you want to have a scientific discussion of specific issues you have with the AGW evidence, please ask your questions and you will get knowledgeable answers. Spit out vitriol and you will get the same back.
5 / 5 (7) Sep 23, 2010
GSwift7: The poster was correct about the difference in temperature measurement methods in the ocean from the time of the war and the time after it. However, is it my understanding that most of those corrections have been applied to the data. I expect the article here is discussing the corrected data. I cannot say for sure they are using the corrected data but the sampling problem has been recognized for a number of years and they were working on the corrections a couple of years back.

This link indicates that they are working with corrected data for their paper:


I have to assume that everyone else would also be using the corrected data by now.
1.4 / 5 (11) Sep 23, 2010

Skipping the nasty comments in your last reply and preventing the further lowering of this debate let me ask you this.

Lets say for arguments sake I have bought into pro-AGW and am now in agreement with you. How then is the proposed Carbon Credits trading system which is already in place and being managed by the rich and powerful like AL Gore who would make Billions from its forced use upon the public, how is that going to fix this pro-AGW problem?

If you can logically make the case for this solution then you will have done more for your cause then anyone else.
5 / 5 (8) Sep 23, 2010
YSLGuru: Isn't this sort of asking me if I still beat my wife (with no answer that doesn't make me look like a wife beater)? You add to your question the assumption that rich and powerful Al Gore would be running the operation that is fleecing you of your hard earned money. I specifically reject that view. Since it has not been decided how a cap-and-trade will be managed, I am not buying into your view it will be corrupt and profitable. Secondly, I do not think cap-and-trade is the best approach to significant reductions in CO2. However, with those caveats I will bite. Cap-and-trade is supposed to start by giving away a specific number of credits for the carbon that is being emitted. Each year the number of credits is decreased. The fine for emitting more than the amount of credits you have is a number (yet to be decided) that is more expensive than the credits. The result is that business must exchange credits and money while reducing CO2 to avoid penalties. (continued)
5 / 5 (8) Sep 23, 2010
YSLguru: (Continued) There is no firm rule established yet since there is no bill for any carbon regulation. However, the proposed approach is for there to be no cost for the original credits. As they are reduced in succeeding years industry must either reduce their emissions, purchase credits from others who have reduced their emissions, or pay penalties. The idea is to reduce the issued credits to some (yet to be decided) number over some (yet to be decided) time. In that way the amount of carbon/carbon dioxide emitted will be reduced. The same thing has succeeded for sulfur dioxide. Why do you think it would fail for CO2?

As for the billions made by Al Gore, please explain to me how he will profit now that I have explained how cap and trade will lower emissions over time. Also, let me know where I was not clear enough or where I have insulted you so I can clarify and apologize.
1 / 5 (6) Sep 23, 2010
@ Thermodynamics
Per YSLGuru's comments above, it would be foolhardy to say categorically that ALL AGW solutions "result in economic depression and death", just that all the ones being pursued are.

Economies and standards of living are built in part on relatively inexpensive and plentiful sources of energy. Proposed solutions and those being implemented benefit the few at the expense of the many. Superficially it's easy to be attracted to the promise of wind power and PV solar. But look a little deeper at the overall practicality and one can't help balk at the price (and the relatively poor reliability, short and long term).

Another note, as an American, I cherish freedom of choice and open markets. They have planted the seeds or outright taken control of money, banks and can look into all our bank accounts, much of industry, health care, soon food, and now attempting central control and taxation of energy. The excuse is always some "crisis".

How do you not feel stifled?
2.4 / 5 (7) Sep 23, 2010
Thanks Thermo. Once again, you are a fountain of good information (even if your opinion doesn't agree with mine SOMETIMES).

So, what could be the cause of this apparent sudden drop in ocean temp then? Salinity inversion caused by massive fresh water melt? Airborn aerosols seem to be a wrong answer from what I have read, based on timing and degree. Good science always creates more questions than answers, doesn't it? Oh, I love a mystery.

Actually, Theremo, Al Gore and friends will make a good profit from the carbon credit market, if it comes to pass here in the US. The people doing it in the EU and in NZ are making a fortune. The dimishing returns are only theoretical, and increasing energy demand may offset any decreases in carbon output in the long run. It's a net gain for the environment though, even if people do get rich, but probably still not the best way to do it. That's just my opinion though. I'm not an expert.
5 / 5 (6) Sep 23, 2010
GSwift7: I completely agree with you on the point of this being a good mystery. I also agree that there is a lot we don't know about the oceans, atmosphere, sun, and the complex interactions of all of the variables. We don't know a lot and that is the reason I love science. However, we do know some things and that is why I love engineering (note science versus engineering). As an example, we don't fully understand how concrete sticks together. However, we know enough to build a bridge. We know enough to say some things about climate, oceans, and atmospheres. Is it incomplete? Yes it is. Does that mean we cannot say anything useful about it? No it does not.

As for the question of why the cooling, that is one of those big question marks. If you look at the thermal profile of the ocean there is a tremendous heat sink there. If it changes position it can go from a warm surface to a cold surface with an, almost unmeasurable change in the temperature of the depths. Cont
5 / 5 (4) Sep 23, 2010
Continued: I hate the 1000 character limit.

Local changes can happen very quickly and unpredictably due to the stored energy in land, atmosphere, and water. However, that huge heat sink can also change gradually in a general direction and that is where we get glacial periods and interglacials. We are presently warming and that is expected after then end of the last glacial period. Even the huge sink of the ocean is gradually warming. It is the effort of trying to isolate a signal for the influence of human produced CO2 that is extremely difficult and there have been mistakes made by arrogant scientists who don't think they can make mistakes. However, there is also a cadre of real scientists and engineers who have done a yeoman's job of teasing a signal out of the noise. Scientists like those do the difficult work of correcting measurements from decades of samples to correspond with better sampling methods. Continued
5 / 5 (4) Sep 23, 2010
Continued: The scientists who correct those signals do not guess at new results, they go back to heat transfer fundamentals and do the hard work of accounting for the changes in sampling methods, evaporation, and time spent in the air. They used to use a bucket, sling it over the side, bring it up and measure its temperature. The new method has a thermocouple in the water intake for the ship's cooling system and does not expose the water to the atmosphere when sampling. The uncertainty in the measurements has been greatly reduced in this way. That makes this a real mystery of some change in the circulation that has not repeated. As you note, there are things we don't know about the oceans. We are in complete agreement on that. However, we also know enough to be able to say that the water column is gaining temperature slowly.
5 / 5 (4) Sep 23, 2010
Continued: Different subject. How are Al Gore and friends going to make a killing on carbon credits? I decided to take a look at what carbon credits are doing now. It looks like they are not exactly a booming business. It is easy to point fingers and say that Al Gore is going to make a killing - but I am really curious about how that is going to happen.



If it is like a stock exchange we should be able to trade in the credits. However, if Europe is any example it is a very risky business.

Let me give you an example. What if someone comes up with a way to retrofit coal fired power plants so that they can capture their CO2 at a lesser cost than that of carbon credits. What that leads to is those utilities making the investment and then dumping their existing credits on the market - where other utilities are making the same investments. (Continued)
5 / 5 (5) Sep 23, 2010
Continued: The idea that coal fired power plants can be retrofitted to collect and sequester CO2 is not hard to imagine at all. There are at least three ways to capture CO2 from a power plant. The methods are known as Post Combustion Capture (use of amines or other reagents to absorb the CO2 from stack gas), Pre-combustion capture (IGCC), and oxy-fuel combustion. Presently oxy-fuel combustion seems to have a cost lead on the other two approaches. All it needs is a carbon incentive to drive utilities to make the investment. Then, if you have cap-and-trade it leads to the collapse of the carbon credit market. That is the scenario I see for the short term. No killing to be made there unless you are the patent holder for the capture mechanisms (which even though he invented the Internet I don't think Al has). ;-) Let me hear your view of how he will make the money. I don't care if he does, I just want to get in on it.
5 / 5 (6) Sep 23, 2010
ricarguy: I don't feel stifled at all. I feel invigorated. I see a transition from the old energy sources to new ones and I see jobs, American ingenuity, and new types of freedom coming out of our progress. We have changed energy sources for ages. Why would we stop now. As for economic disaster, that does not have to happen at all. Not if we are as clever as I think we are. I am looking forward to the coming new energy fields. Looking at old photovoltaics and acknowledging that they are not cost effective I,actually agree with you. That does not mean we can't do better. It also does not mean we cannot use "clean coal" in the advanced sense of that term (as I mentioned above). I don't see defeat and doom in this challenge, I see opportunities.
1 / 5 (4) Sep 24, 2010
How Al Gore plans to make money from carbon credit brokering:


The people who run the exchanges will make millions from the exchange fees if cap and trade becomes law in the US. The system can be adjusted to assure that the exchanges make money, no matter what happens to actual carbon emissions. The coal companies can choose to buy carbon credits in stead of installing carbon sequestration equipment, depending on which is cheaper in the long term. If it looks like carbon credits are going to be cheap in a few years, then why bother installing multimillion dollar scrubbing equipment? You see, there's a limit built into the cap and trade system that makes sure the credits won't become too cheap. Companies will do whatever is the cheapest solution, not the enviromentally best solution. If anyone is selling credits cheaply, the power companies will just buy those credits in stead of installing clean equipment. Of course, other ...cont.
1 / 5 (2) Sep 24, 2010
continued... Of course other companies will be bidding for those cheap credits too, so the eventual selling price will be higher than the credits were sold to the broker for. The difference in price is profit for the broker and then there's also the futures market, which is like free money for the brokers. They make money even if the price goes down in the futures.
1.6 / 5 (5) Sep 24, 2010
The other problem is that you won't end up seeing the worst sources of CO2 get fixed. Here's an example to demonstrate why: If I'm making 1 ton of CO2 per day more than I'm allowed then I have three options. First, I can install a system to reduce my CO2 by 1 ton per day. Let's say that will cost me 100 dollars (sticking to a one-time cost for simplicity). My second option is to buy carbon credits from someone who has is producing less CO2 than the cap allows them. Let's say Skeptic Petroleum Inc. put a credit up for sale at a brokerage and the current bid on that credit is $90. That sounds good to me, but there's a third option. I can fund a carbon reduction project that the UNFCCC has approved and granted them some carbon credits that they can sell. So let's say Thermodynamics Solar Inc is going to put solar panels on the backs of cows to power electric methane traps and the UNFCCC gave him a credit for the idea, then he may sell me his credit for $80.
1 / 5 (4) Sep 24, 2010
Artificial Markets created by the state fail to meet their stated objectives, but do enable those with an inside track to gain advantage. Enron supported Kyoto as did/does BP, and they promote politicians who do as well.
not rated yet Sep 26, 2010
So the reason why global-scale warming is so hard to detect in the 20th Century is that its effects were mitigated by concurrent global-scale cooling?


I left adolescence behind me a couple of decades ago, but every time my mother sees me she swears I have grown. Obviously, the only reason I'm not nineteen feet tall is that my runaway post-adolescent growth (confirmed by a consensus of female relatives) is mitigated by the fact that--for some unknown reason--I am also shrinking at exactly the same rate!

LOL, Funny.

And something else puzzles me. The ocean has to be around 28f to freeze, right? Well, if the southern ocean is warming, why has the Antarctic ocean ice pack been expanding the past 30 years?

Source: http://www.uwgb.e...aIce.HTM

Seems odd, don't you think? LOL
1 / 5 (2) Sep 26, 2010

Why do the climate scientists think global warming is a problem that must necessarily be mitigated? Many benefits to warming are evident in the climate fossil record, and in apparent fact today.
5 / 5 (3) Sep 26, 2010
ubavontuba: You asked a good question. Think in terms of what actually happens when climate changes permanently. Take a look at maps and see how areas are used for agriculture, manufacturing, fishing, etc... There are two things that will happen. First, the wild animals that cannot adapt will die. I suspect you don't worry much about that. Second, the human population centers, cities, transportation, etc, are based on thousands of years of adaption to a slowly changing climate. Now,if things change quickly, wildlife will be in deep trouble. Areas where food was produced may not be able to now. Coastal cities shall be subjected to weather in conjunction with climate that most people don't think will be good. Floods, drought, changes in land use, changes in the oceans, requirements for more energy to control the temperatures where people stay. Just what part of that do you see as good?
2.3 / 5 (3) Sep 26, 2010

That seems to be a rather pessimistic point of view.

I wouldn't worry too much about human cities. Humanity has long been able to manage extreme environments (Have you ever been to Phoenix in the summer, or Bismarck in the winter?).

Regional flooding is a concern, but historically has been mitigated, as needed.


Wildlife stress is also a concern, but most wildlife is surprisingly adaptable. In fact, persistent stresses bring about evolutionary change.

However, (generallly speaking) as GW increasses worldwide precipitation, the main effect on wildlife (it seems) would be to provide more green environs in which to thrive (supported by the fossil climate record, and current trends).

And as farms go, agriculture itself has long been adaptable to migration and change. Did you know that Greenland farmers are bringing in record harvests?

2.3 / 5 (3) Sep 26, 2010
Think in terms of what actually happens when climate changes permanently.

When has there been a permanent change in climate?
2 / 5 (1) Sep 26, 2010

Animals would be perfectly capable of adapting if were not for the land confiscation of humans (i.e. fences, dams, reclaimed marsh land, etc). Ice age climate models take up roughly 90% of the past 5 million or so years of Earth's climate.

Personally, I think this is 95% related to the Sun's output and Earth's own orbital relationship to it. What little anthropogenic effect is occurring, pails by comparison.

Do I think humanity is severely altering the ecosystems on Earth, absolutely. But the larger and long term effects of the climate should be placed where it belongs - the Sun and its varying cycles - known and unknown alike. I'm pretty sure there are solar cycles that are on time scales that are beyond our current scope of perception, let alone accurately measuring them.

Anyway, that's my 2 cents on this topic.
3.5 / 5 (2) Sep 27, 2010
House of cards built on a stack of premises, Do we have sound science to say without a reasonable doubt- we understand the consequences of carbon dioxide and its effect long term on the environment? no-stop, yes-next question: Is global warming real? no-stop. yes-> next question: Is global warming caused by man's emission of carbon dioxide? no-stop. yes-> next question: Is global warming inevitable? yes-stop. no-> next question: Is global warming economical to prevent? no-stop. yes-next question: is there global political will to fairly distribute the responsibility for carbon mitigation? no-stop. yes-next question: will the worlds political powers maintain their economic commitment to control the emissions of carbon indefinitely? no-stop. yes-continue.
So, excuse me if I am not rushing to concur with the hype. There's a lot of assumptions being peddled here without a lot of realistic solutions to ease my apprehensions. A prius and water bottle isnt going to cut it you know..
1 / 5 (1) Sep 27, 2010
With due respect Thermo:

"Think in terms of what actually happens when climate changes permanently"

Are you presenting an example from history? Can you please point to which specific period of climate change you are using for your example? It looks like you are kinda combining all the worst effects of many different kinds of changes in many different regions over many different time periods. Please clarify what period/region you are using for your examples here.

"First, the wild animals that cannot adapt will die."

Can you give an historical example of what you're talking about here? If you are talking about ice ages, then that's hardly a fair comparison to anything happening in our near geological future. If you're talking about warming periods, then the geological record shows increased biological diversity, despite extinctions in some species adapted to colder climates. Warming also leads to expanded areas of temperate climate, speaking strictly from geological evidence.
1 / 5 (2) Sep 27, 2010
"Second, the human population centers, cities, transportation, etc, are based on thousands of years of adaption to a slowly changing climate"

Can you please list the modern population centers that have been around for longer than 2000 years in thier current locations? I don't think there are very many compared to the total number of modern population centers. I'd be surprised if one in a hundred have been around for longer than 500 years, much less the "thousands" you are suggesting.

"Now,if things change quickly,"

Define "quickly" and "things change" in terms of time scales and magnitude of change. What is realistic versus Hollywood fantasy?

The most extreme model results aren't looking very accurate right now, so I'd like to know what you are using as evidence that the calamity you propose is likely.
1 / 5 (2) Sep 27, 2010
"Just what part of that do you see as good?"

None of it, but what percentage of that junk you just said do see as real? Almost all of the preceding few sentences is speculation and only the most extreme liberal environmental fearmongers believe any more than a small portion of it. You'll have far more success keeping someone like me engaged in the conversation if you stick to more believable reasons to change our social habits. There are plenty of GOOD reasons to adopt more responsible ways of living. Why go off the deep end when you don't have to? What you say is like saying that we need space exploration so that we're ready to defend ourselves when the aliens attack. Just think of the urban devastation, loss of life and freedom, global death-ray damage. What part of alien invasion do you see as good? Just like space exploration, there are many great reasons for environmental progress. Keep it real. You aren't going to convert anyone who doesn't already believe that the alarmism.
3 / 5 (2) Sep 27, 2010
House of cards built on a stack of premises, Do we have sound science to say without a reasonable doubt- we understand the consequences of carbon dioxide and its effect long term on the environment? no-stop, yes

So how do you explain the rapid changes in climate during the past 10 ice ages? Where humans around during these times? If anyone is laying an assumption, its you.

When the climate warms up, after any given ice age epoch, life probably tends to explode on a global scale, hence the increase in over gases of all types until it reaches equilibrium.

I'm not saying what humans are doing to the Earth, from an ecological stand point, is a great thing. But 90% of the time, Earth resides in ice age conditions, this is pretty much scientifically established.

Explain why the Earth warms up after a 100,000 glacial epoch? Not just once, but time and time again. I'd say the source is the SUN and the Earth's relation to it - the orbital patterns.
1 / 5 (2) Sep 27, 2010
"Explain why the Earth warms up after a 100,000 glacial epoch? Not just once, but time and time again. I'd say the source is the SUN and the Earth's relation to it - the orbital patterns"

Don't forget about changes in ocean currents due to changes in the positions of continents. North and South America haven't been connected for very long, for example. The mild winters and summers of our Southern Hemisphere are due to the present circumstance of the oceans.

"When has there been a permanent change in climate?"

exactly what i was thinking. lol
not rated yet Sep 27, 2010
Don't forget about changes in ocean currents due to changes in the positions of continents. (abbreviated for character length)

And what heats the oceans? The moon or some yet undiscovered heat source? No, it's the Sun. The cycles are well established, 90% ice-age climate, 10% inter-glacial climate.

Even super volcanic events (which by the way put the Earth's climate into a no man's land) do not significantly alter the general trend of these climatic patterns.

Technically, we are still in a ice-age and concurrently in a inter-glacial epoch.

Long Term: (500+ million years) http://en.wikiped...aciation

Short Term: (5 million years) There has been a general cooling trend, culminating in at least 10 glacial epochs - each of which - lasting around 100,000 years.


It should be noted, the previous inter-glacial epoch was actually warmer than today, which was roughly 120,000 years ago. It's the Sun/Earth relationship.

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