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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Are we heading into a new Ice Age?

What the science says...

Select a level... Basic Intermediate

Worry about global warming impacts in the next 100 years, not an ice age in over 10,000 years.

Climate Myth...

We're heading into an ice age

"One day you'll wake up - or you won't wake up, rather - buried beneath nine stories of snow. It's all part of a dependable, predictable cycle, a natural cycle that returns like clockwork every 11,500 years.  And since the last ice age ended almost exactly 11,500 years ago…" (Ice Age Now)

At a glance

In something like a Day after Tomorrow scenario, the idea that a new ice-age was just around the corner was the subject of a book, a DVD and a website created in 2002. The author was a retired architect, by the way. Fortunately for us, both the movie and the quote above are figments of someone's fertile imagination. But let's have a quick look at ice-ages and what makes them tick, after which we hope you will agree that the notion that another ice-age is just around the corner is nonsensical.

Ice-ages, also known as glacials, are cold periods that occur in a cyclic fashion within an Icehouse climate state. Earth's climate has been mostly of the Hothouse type (no Polar ice-sheets). However, on occasion it has cooled down into Icehouse, as has been the case in the last few million years. There are regular variations in Earth's orbit around the Sun, taking place over tens of thousands of years. These affect the amount of Solar radiation reaching our planet. During the Icehouse state, such variations can lower and raise planetary temperature sufficiently to trigger swings between cold glacials – when ice-sheets expand towards the Equator – and mild interglacials – when the ice retreats back polewards.

To give an idea of the time-scales involved, Europe and North America have seen glacials and interglacials come and go repeatedly over the last 2.5 million years, this being known as the Quaternary Period of geological time. The last glacial period started 115,000 years ago and the Last Glacial Maximum (LGM), when the greatest ice extent was reached, was around 22,000 years ago. The current interglacial – also known as the Holocene, commenced 11,700 years ago.

A general pattern may be seen here with a long cooling down towards Glacial Maximum but a relatively quick warming into an interglacial. The speed of the warming-up part of the cycle is due to climate feedbacks. Removal of pale, reflective snow and ice cover revealing the darker ground beneath allows more solar heat energy to be soaked up. Melting of permafrost releases carbon dioxide and methane. These and other feedbacks serve to amplify the warming effect, speeding it up.

However, our burning of fossil fuels has happened on such a vast scale that we have blown such factors apart. The atmospheric concentration of CO2 has risen well above the 180-280 ppm range typical of recent glacial-interglacial cycles. The current level, getting on for 420 ppm, is more typical of the mid-Pliocene. That was a geological epoch that happened around a million years before the start of the Quaternary. Mid-Pliocene ice-sheets were much smaller than those of the present day. Rather than being due another glaciation, we can expect a continued transition towards mid-Pliocene conditions.

Please use this form to provide feedback about this new "At a glance" section, which was updated on May 27, 2023 to improve its readability. Read a more technical version below or dig deeper via the tabs above!


Further details

Because our current interglacial (the Holocene) has already lasted approximately 12,000 years, it has led some to claim that a new ice age is imminent. Is this a valid claim? No.

To explore this topic further, it is necessary to understand what has caused the cyclic shifts between ice ages and interglacials during the Quaternary period (fig. 1). Such shifts are in part a response to regular changes in the Earth’s orbit and tilt, which affect the amount of summer sunlight reaching high northern latitudes and were described by the Milankovitch Cycles, first proposed in the early 20th Century by Serbian mathematician Milutin Milankovi? (1879-1958). For more about Milankovitch cycles this NASA page offers lots of graphics and explanations.

Figure 1: Temperature change through the late Quaternary from the Vostok ice-core, Antarctica (Petit et al. 2000). The timing of warmer interglacials is highlighted in green; our current interglacial, the Holocene, is the one on the far right of the graph.

When incoming sunlight declines in the high north, the rate of summer snow and ice-melt declines and the ice sheets begin to grow. When incoming sunlight increases, the opposite happens. So where are we in these cycles today? Changes in both the orbit and tilt of the Earth do indeed indicate that – were they singularly responsible for climate shifts - the Earth should be slowly cooling. However, recent research shows that is too simple. That's because we now have analyses of ice-cores going back 800,000 years or more. We have devised ways to use stable isotope ratios of various elements in things like fossils and we have developed many other proxy methods for telling us more about conditions in the relatively recent past that the Quaternary represents.

A number of irregularities in glacial-interglacial cycles have been determined, for example times when interglacials were skipped when orbital patterns suggest they should have happened. (Koehler and Van de Wal 2021). Such research has also been aimed at resolving the question of why Earth's 41,000 year obliquity cycle was a strong driver of glacial-interglacial transitions up until around one million years ago. Since then, glacials have instead typically lasted for much longer - around 100,000 years.

The importance of feedbacks within Earth's climate system has been increasingly recognised as the decades have gone by. A good example is the speed of transition from glacial to interglacial, which is relatively rapid because certain very effective climate feedbacks are involved. One such feedback involves albedo, defined as the ability of different bodies to absorb or reflect sunlight (e,g, Thackeray and Fletcher 2016).

Albedo is expressed on a scale of 0 (black body, absorbs everything) to 1 (white body, reflects everything. Fresh snow has a high albedo of as much as 0.9, whereas the muck revealed when old snow and ice cover melts has a much lower one in the range 0.2 to 0.4 – it can absorb lots more solar energy. So melting snow and ice leads to more heat energy retention, amplifying the warming (Fig. 2). 

Albedo Explainer (John Mason)

Fig. 2: Albedo feedback explained. Freshly-fallen snow is highly reflective of incoming sunshine, so that most of the solar energy is simply bounced back towards space. Bare sea ice can potentially absorb about half of the incoming energy, so if conditions become warmer, causing the snow to melt, there’s more energy retained on Earth. If the sea ice melts too, then almost all of the incoming solar energy is absorbed by the much darker surface of the sea. So an initial warming directly results in further warming. Graphic: John Mason.

Another feedback happens when permafrost gets thawed out, since the ground is then able to release previously trapped CO2 and methane. During a glacial, the extent of permafrost is vast, so as it thaws, the release of such gases occurs on an enormous scale – again, amplifying the warming.

Researchers have also modelled ice-sheet dynamics, investigating how the sheets behaved as they melted, for example. It has been found that the shorter-lived, lower latitude Northern Hemisphere ice-sheets that existed prior to one million years ago were much thinner and therefore easier to melt. So ice-sheet dynamics looks to have a role in the much longer freeze-ups of the past million years. This all goes to show that glacial periods arise through a whole lot of factors interacting with one another, of which orbital cycles are but one, albeit important, cog in the gearbox and are not necessarily able to drive the climate system from one state (glacial) to another (interglacial) in total isolation (e.g. Bintanja and Van de Wal 2008; Berends et al. 2021).

Talking of cogs in the gearbox, we are another – and a big one. Our intentional disturbance of carbon reservoir rocks – what we do when we seek, extract and burn the fossil fuels – is unique in the geological record. It's a one-off in the planet's 4.56 billion year long history and while the consequent overloading of atmospheric CO2 levels is still insufficient to take Earth back into a Hothouse state yet, it is perfectly adequate to prevent another glaciation any time soon.

Last updated on 27 May 2023 by John Mason. View Archives

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Argument Feedback

Please use this form to let us know about suggested updates to this rebuttal.

Further reading

Tamino discusses predictions of future solar activity in Solar Cycle 24.

Acknowledgements

Many thanks to Sami Solanki for his invaluable advice and feedback as well as John Cross for his very helpful comments.

Further viewing

potholer54 published a video tackling this myth on June 27, 2020

 

Dave Borlace explains why we are not headed towards an ice age in this "Just have a think" video published in December 2019:

 

Denial101x video

Comments

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Comments 201 to 225 out of 411:

  1. Henry Justice @198 - "Also, I checked the worlds annual mean temperature charts. Not much of a visual upward slant in temperatures everywhere I looked world wide for the last 50 years. The urban site temps were not used as they are unreliable. So upward and downward wiggles appear all but natural variations. Look for yourself and you be the judge!" Okay. Comparing all the temperature records Henry, the three surface temperature records and both satellite records all show warming. Where have you been looking?.
  2. Henry Justice - " In Greenland, eight WW2 bombers from the "lost squadron" were found in 1986 under 267 feet of ice. How's that for melting glaciers? I didn't take the rest of the article seriously." Yeah, heard that one before. And the one about the research station being buried under many feet of snow, and having to be dug out. Please note that the center of the Greenland Ice sheet is at high elevation, is very cold and is still accumulating ice. The coastal regions where the glaciers meet the sea, are not, and are rapidly melting. The loss of ice at the coast far exceeds the gain from snowfall at high elevation, this is why the Greenland ice sheet is losing many billion of tonnes of ice every year.
  3. Henry @198, I'm afraid you have been hoodwinked by some folks who, on the surface, seem to make a compelling case. Research has shown that even if we do enter another Maunder-like minimum, or even a grand minimum, the radiative forcing from elevated GHGs will easily overpower the reduced incoming solar radiation. See this thread for details.
  4. #195 . WRONG !!! the satelites together with earth should form one system that it should be moved together in the apply of gravitational forces due to planetary realligment , yet the sun stays steady ....
    Response: [Daniel Bailey] Again, please provide linked references for those claims (published, peer-reviewed sources have the most credibility). Extraordinary claims must of necessity be accompanied by an extraordinary evidenciary chain. Unsupported comments such as yours will be simply deleted in the future. Thanks!
  5. @kfdv #190 Are you aware this is all written, aren't you? What do you suppose students will think about when they analyze your answer to #188 ?
  6. Have any of those individuals pointing to the “Petit 2000” graph actually bothered to look at it and study what it means? According to the graph if you move backward through time to "now" you see a rapid increase in temperature - consistent with other ice ages - but the highest temperature reached, during the present temperature increase period, never reaches the same high it reached in previous ice ages. The high in previous periods is over 3 deg above the baseline whereas it is less than 2 deg above the baseline for the present. How can anybody interpret this as a temperature rise that’s out of control? If we’re in the middle of a glacial warming period it stands to reason that each year will be warmer than the next until the warming trend ends. BTW: The most efficient way to transfer thermal energy is by convection. If you remember your physics there are three ways to transfer thermal energy – radiation, conduction and convection. Why does the GW model only consider the meager role of radiation heat transfer when convection heat transfer is far more efficient?
  7. Dorianmc, Firstly, who said we were undergoing runaway temperature increases? So far warming has been very tightly controlled, doing pretty much what climatologists said it would do in reaction to increasing CO2 levels. Secondly, we're in the middle of an interglacial period that should be cooling according to natural forcings, but it isn't. Temperature is spiking rapidly on a geological timescale. Thirdly, exactly how do you know that radiative transfer is "meager"? And what gives you the bizarre idea that convection isn't taken into account? Which model states that only radiative effects are taken into consideration? Your previous post is a rambling mess of assertion.
  8. Dorianmc forgets (or is unaware) of the multiple layers of the atmosphere and that at the level of the TOA, convection is largely non-existent and radiative transfer rules. And that at no point in the last several interglacials did CO2 concentrations ever approach what they are today, heightening the importance of back radiation. Also remember that the zero baseline of Petit 2000 was 1950. Let's take a look at that whole timeframe, extending it to today's CO2 levels: A re-watching of Alley's talk would be instructive here. The Yooper
  9. #206: "it stands to reason that each year will be warmer than the next until the warming trend ends." That would be nice, if we lived in some kind of cartoon-world, where the requisite laws of cartoon physics apply. However, you may be aware we had a 'Little Ice Age' and have fully recovered from that. So your idea that there's any possibility of monotonically increasing temperatures is not even lukewarm.
  10. Perhaps I'm missing something,but several things jump out of this graph: 1) The data only goes back about 430,000 years, yet the axis goes back 450,000 years. Why? To me it looks as though someone has removed the first part of the line. I'm not saying they did, but such things do happen from time to time. In this instance it's a fairly critical question because the interglacial that occurs at the left of this graph is allegedly the closest fit to the one we have now in terms of the alignment of the planet. 2) It is apparent that the later data is at a high level of granularity than the more recent data, you can see this by the spikiness (thickness) of the line. This is not surprising because the closer we get to the present the more data we have. However it does somewhat skew one's perception of the graph because when we look at 430,000 years ago compared with now, we are not - in graph terms - comparing apples with apples, due to the granularity difference. I strongly suspect that if the graph was drawn with uniform granularity then the temp change 430,000 years ago would appear more similar to the present temp change. 3) The temp peak in this current interglacial is presently a very thin one at 2C. Other than that the temp appears to be hovering somewhere between 0-1C, this is actually lower than in pervious interglacials, all of which peak between 2-4C. 4) There are only really 5 samples of interglacials represented here and that really isn't much of a data set. Now I fully appreciate that this can;t be help given the time periods in question, but it doesn't change the fact that there are only 5 samples for comparison. Humans are as yet hopeless at predicting localised weather let alone the climate. This doesn't mean people shouldn't try but perhaps they should hold back predicting catastrophes until we have a better understanding. For all we know the super volcano in Yellowstone National Park could go off in a few decades and that would really throw a spanner into the works. The Earth is a living planet, and nature takes no prisoners. Personally I am glad of all this hoo-har over climate change because if nothing else it is teaching people not to mess around with nature. Unfortunately that doesn't mean that won't mess around with us and everything else on this planet. If nature chooses to make some changes then - take note kids - human beings are powerless to do anything about that. Get used to it. In LVX
  11. Here is the full graph. Shows a more similar curve between 430,000 years ago and now: http://commons.wikimedia.org/wiki/File:Ice_Age_Temperature.png
    Response: [Daniel Bailey] Not so similar. Remember that ice core temperature reconstructions use 1950 as year zero. Here's what that would look like if CO2 were extended to today's levels (I do seem to be having to show this illustration a lot lately!):
  12. #210: "if the graph was drawn with uniform granularity..." If the graph was drawn uniformly, it would be a misrepresentation of the data. The time resolution of an ice core (and many conventional cores) decreases as you move downhole (older). Petit et al 1999 is the classic description of how these data are obtained. The mean resolution of the CO2 (CH4) profile is about 1,500 (950) years. It goes up to about 6,000 years for CO2 in the fractured zones and in the bottom part of the record "... only really 5 samples of interglacials represented here and that really isn't much of a data set." Why is this a concern? This isn't a pattern matching exercise.
  13. Re: Blueflash (210) 1. Read the study (petit et al 1999) 2. IBID. Then read this. 3. You expect all glacial epochs to be Xerox copies? 4. 450,000 years of data, multiple cores. Say what you want, but it doesn't change the fact that that's an awful lot of years and even more snowflakes. Humans do a pretty good job at understanding past and present ongoing climate change and predicting future climate changes. Strawmen distractions about off-topic supervolcano's aside (we are overdue for a Yellowstone blow, tho), human beings are pretty capable of screwing the planet up. Get used to it. The Yooper
  14. Daniel, 1) The graph I was referring to was a temperature graph. The one you have responded with is a CO2 graph. 2) "For 650,000 years, atmospheric CO2 has never been above this line... until now" uses misleading grammar. The word "never" has strong implications. And 650,000 years is not a long time in the grand scheme of earth. The correct phrasing would be "CO2 has not been above this line in the past 650,000 years."
    Response: [Daniel Bailey] Sigh. In reverse order (feeling contrarian myself today), 650K years is an immense time in the history of our species; the Earth will abide long after we are gone (unless we get too many handwaving comments). CO2's peak in the Vostok core was 298.3 PPM. The line was to represent 300 PPM. Grammar concerns notwithstanding, the point is unequivocal. And for those who refuse to acknowledge any relationship between CO2 and temps:
  15. Please excuse my ignorance, but are you saying that the increased CO2 levels responsible for global warming have kept us from entering into an Ice Age? Shouldn't we be glad of that? Or is it the case that this global cooling period/Ice Age wouldn't have affected us in our lifetime, or the lifetimes of future generations and as such wouldn't have been of concern anyway? I'm just a little confused now.
  16. The current interglacial would have ended in about 10 thousand years based on the natural cycles. Hence, not really a concern for humanity.
  17. Re: Mr_Pants (215) Welcome to Skeptical Science!
    "Please excuse my ignorance, but are you saying that the increased CO2 levels responsible for global warming have kept us from entering into an Ice Age?"
    I'm not saying it is or isn't in the definitive sense, but the emerging evidence would seem to indicate that.
    "Shouldn't we be glad of that?"
    Dunno. Personally, I'm glad to have a job and a family that loves me.
    "Or is it the case that this global cooling period/Ice Age wouldn't have affected us in our lifetime, or the lifetimes of future generations and as such wouldn't have been of concern anyway?"
    Absent the warming effects of the CO2 bolus we've injected into the air, then the understanding is that the Earth would've continued its gradual cooling trend from the Holocene Optimum for at least the next several thousand years before any onset of an ice age would've become worrysome. But that's neither here nor there. Of bigger and more immediate concern is what damage the warming still in the pipeline will do to our climate and crop production:
    "I'm just a little confused now."
    Been there, done that. The Search function in the upper left corner of every page is your friend here. If you have questions, type in a few keywords & search away. Odds are there's a thread or three here covering that topic. For some good background on Skeptical Science and climate science in general, go here and here. Enjoy! The Yooper
  18. Even if there was eminent danger of mile-high sheets of ice sitting on Minnesota, such as in 'Fallen Angels' by Larry Niven, we have already drastically overshot the mark.
  19. #218: Biblio, Maybe we could build a Ringworld. It would be cooler (from a scifi point of view).
  20. @ 219 I hear General Products was founded by Koch Industries... The "Louis Wu" Yooper
  21. #220: Ha! Even the Puppeteers were done in by what could only be called PGW The Puppeteers had to make some drastic alterations to their home system, during their history, as waste heat due to overindustrialisation was rapidly making their planet uninhabitable. They moved their planet further from their sun, to lessen the effects of global warming ...
  22. @ 221 You mean...they had their own waste heat thread? One is enough to do in any civilization, apparently.
  23. There seems to have been several comments in this thread regarding the shifting of the axis of the planet. I don't know whether those who propose such things simply do not understand how the planet moves in space and interacts with it's environment, or are simply misunderstanding some real events and relationships. For the record. The axial tilt of the planet moves. Over a period of about 41,000 years it gradually "wobbles" from 21.2° to 24.1°. On it's own the effect on climate will not be that great as it accounts for something in the region of a variance of about 0.021 W/m² of solar radiance, hardly enough to have a drastic input on it's own. This wobble has a wobble imposed upon, that also has a wobble..you could say that the wobble has a wobbling wobble!! However, joking aside, these are minor and do not have any real effect. There is no evidence that I am aware of showing the axis of the planet has ever exceeded the extremes of the wobble I mention in the last 4Gy, thus I think it unlikely too now. Where I feel many laymen get confused is between the axial pole and the magnetic pole, which are wholly separate. The Magnetic pole wanders about like a drunk, all over the place and up to 40km per year, currently it holds a Canadian Passport! Further, it is a proven fact that the magnetic pole does "flip" and also disappears for short periods, perhaps up to 10,000 years, and this process is not understood really, although theories abound as to the cause. Whether there is an interaction between these magnetic reversals and the climate I do not know, I don't think any research has been done in this respect, but I stand to be corrected on this. Any sceptic who claims that the axis of the planet changes drastically and this causes Ice Ages, Warm periods, sea level changes or even the death of species is talking out of their hat and they do not do the debate any favours at all as they simply make those who question the climate research conclusions seem like crack pots. Now perhaps we can avoid discussion of the planets axis moving and stay on track?
    Response: I'm unsure whether you are arguing against the existence of Milankovitch cycles, but if you are, you are wrong. You can see Richard Alley explain it in 30 seconds. Doing an internet search for "Milankovitch cycles" will get you a bunch of diagrams, animations, and explanations. That will help you understand when you reread the original post at the top of this page.
  24. @ Response...surely you have a name :) I am unsure why you feel I was arguing about Milankovic cycles, and I wonder if you read my post correctly? I am not arguing against Milankovic cycles in the slightest, on the contrary, I am a firm believer that these cycles can and have played a part in the varying climate here on Earth, but I think this is only when they coincide with other effects that are "home grown" on Earth and simply add to it. My comments are self explanatory, the axis of the planet does not shift beyond the natural variance I noted and firmly believe that many get this mixed up with magnetic pole displacement, which is a proven scientific event in Earth history. Many seem to misunderstand the motion of the planet in space, and seem to think these changes have a greater impact on Earth than they do. Combined they may well have a big effect, but as far as I am aware, no-one has created a model of the solar system accurate enough to models our planet's motion in space over the last 4 billion years to see whether, at any time, the disparate cycles have ever coincided enough to have anything more than an arbitrary effect. That is why the last paragraph of my post was worded the way it was. I am not convinced by AGW, but if one is to argue against something, then one must do it with credible arguments that at least are worth research time, and polar shift of the planet is not one of them
    Response: You just now did argue against the dominant role of Milankovich cycles in triggering ice ages. Make up your mind.
  25. #224: "models our planet's motion in space over the last 4 billion years ... " A complete and utter red herring strawman. There is more than enough understanding of the current orbital dynamic to fully describe the orbit's control over solar insolation. There is more than enough measurement of insolation to fully describe its input to earth climate. "... to see whether, at any time, the disparate cycles have ever coincided enough to have anything more than an arbitrary effect." What does that even mean? What is an 'arbitrary effect'? "I am not convinced by AGW" Let's try to establish credibility rather than make declarations. Have you read each of the SkS threads relevant to whatever aspects of AGW you disagree with? Have you weighed the arguments of actual scientific research against 'I am not convinced'? What specifically do you disagree with? Can you mount credible cases against the points made in the relevant SkS threads to qualify as scientific arguments? Those who arrive at SkS already in a confirmed state of denial usually wind up with little more to do than pose red herrings and make blanket 'no its not' statements. Nobody said understanding AGW was easy; being a competent skeptic certainly isn't easy either.

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