# There will be another ice age. True? (Yes, true...but when?) **URL:** \ **Category:** Great Debates\ **Created:** [October 17, 2014, 3:09am UTC](https://boards.straightdope.com/t/there-will-be-another-ice-age-true-yes-true-but-when/701561 "2014-10-17T03:09:49Z")\ **Posts on this page:** 11\ **Page:** 2
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 20, 2014, 3:52am UTC](https://boards.straightdope.com/t/there-will-be-another-ice-age-true-yes-true-but-when/701561/21 "2014-10-20T03:52:10Z")
> [@Martin\_Hyde](#): > > I also find it unlikely carbon is the driver of geological scale climate change. If that were the case we never could have gone to an ice age from the 1800-2200 ppm carbon concentrations we’ve seen in the past. For natural climate change carbon is probably a trailing indicator and likely it is indeed those rare events (which geologically are about as rare as a person having a heart attack) that cause significant changes. Not so. > **[Ice age study delivers blow to global-warming skeptics](https://www.csmonitor.com/Environment/2012/0405/Ice-age-study-delivers-blow-to-global-warming-skeptics)** > > A new study finds that rising levels of carbon dioxide drove rising temperatures at the end of the last ice age. The findings contrast with previous studies, which skeptics of human-triggered global warming said showed that CO2 levels weren't an... > [@](#): > > Ice age study delivers blow to global-warming skeptics > > A new study finds that rising levels of carbon dioxide drove rising temperatures at the end of the last ice age. The findings contrast with previous studies, which skeptics of human-triggered global warming said showed that CO2 levels weren’t an important factor. > > Rising levels of carbon dioxide drove much of the global warming that thawed Earth at the end of the last ice age. > > That’s the conclusion a team of scientists has drawn in a new study examining the factors that closed the door on the last ice age, which ended about 20,000 years ago. > > The result stands in contrast to previous studies that showed temperatures rising ahead of increases in atmospheric CO2 levels. This has led some skeptics of human-triggered global warming to argue that if warming temperatures came first, CO2 wasn’t an important factor then and so can’t be as significant a factor today as most climate scientists calculate it to be. > > The measurements from the previous studies were taken from ice cores extracted from thick glaciers in Antarctica. The new work supplements that data with temperature evidence from 80 locations around the globe. > > The results show that while temperature increases around Antarctica appear to have led increases in atmospheric CO2, the picture globally was the opposite – CO2 increases paved the way for temperature increases. ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [October 20, 2014, 4:27am UTC](https://boards.straightdope.com/t/there-will-be-another-ice-age-true-yes-true-but-when/701561/22 "2014-10-20T04:27:44Z")
> [@Martin\_Hyde](#): > > It’s odd you want to talk of science and Milankovitch cycles but feel the proper definition of an ice age is “too confusing” and thus presumably shouldn’t be used. I see nothing odd about pointing out, in the interest of clarity, that when we speak of “ice ages” we are usually talking about the geologically rapid cycles of glaciation in the Quaternary, which are geologically recent and an important part of the history of modern climate, certainly more relevant to contemporary climate change than something that happened 34 million years ago. You can feel free to use the term to mean whatever you like. > [@Martin\_Hyde](#): > > It’s unlikely that man has altered any climate constant precisely because there is no such thing. You’re talking about the last sliver of geologic time as though it’s representative of anything meaningful geologically. I don’t know what you mean by “climate constant” as that isn’t a scientifically meaningful term. We have certainly altered CO2 very dramatically, and we have taken it out of the narrow range in [which it has existed for a million years](http://upload.wikimedia.org/wikipedia/commons/b/b8/Vostok_Petit_data.svg). Indeed since industrialization we have increased it from the normal post-glacial maximum by a greater margin than its entire excursion from the depths of an ice age to the peak of an inter-glacial. That is a truly monumental change in CO2 forcing with major implications for the future of climate. > [@Martin\_Hyde](#): > > i also find it confusing when you say scientifically stupid things like “ice age cycles of the last million years.” Then educate yourself. Just because you haven’t heard of something doesn’t make it “stupid”. When I say “ice age cycles of the last million years” that is exactly what I mean – [the 100 Ky cycles shown here](http://upload.wikimedia.org/wikipedia/commons/f/f7/Five_Myr_Climate_Change.svg). > [@Martin\_Hyde](#): > > I also find it unlikely carbon is the driver of geological scale climate change. [The laws of physics](http://en.wikipedia.org/wiki/Radiative_forcing#Forcing_due_to_atmospheric_gas) frankly don’t care if you “find it unlikely.” > [@Martin\_Hyde](#): > > If that were the case we never could have gone to an ice age from the 1800-2200 ppm carbon concentrations we’ve seen in the past. For natural climate change carbon is probably a trailing indicator … False. The drop in atmospheric carbon levels occurred over a long period of time (millions and tens and hundreds of millions of years) in response to large-scale geophysical and biophysical changes in the earth’s evolution, like reductions in CO2 outgassing from volcanoes and metamorphic belts and long-term changes in the ecosystem that resulted in increased carbon sequestration. And no, carbon isn’t a “trailing indicator” – it may not always be the initiator, but basic physics dictates that GHGs are major determinants of climate, not just on earth but everywhere. There is a difference – as in the drivers of the 100 Ky ice age cycles of the past million years – between the initiator of a climate transition and its primary sustainer. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [October 20, 2014, 11:01am UTC](https://boards.straightdope.com/t/there-will-be-another-ice-age-true-yes-true-but-when/701561/23 "2014-10-20T11:01:31Z")
> [@Learjeff](#): > > I wonder if we’ll get to the point where one country is trying to push the climate in one direction and another is doing the opposite. Climate wars! Not that it would stop anyone really, but there’s a specific Geneva Convention against using weather as a weapon, [ENMOD](http://en.wikipedia.org/wiki/Environmental_Modification_Convention). Although it looks like we haven’t signed it, so when I’m God-King of [Azania](http://en.wikipedia.org/wiki/Azania#South_Africa), you should all fear my icy wrath! ---
**Author:** ![Martin\_Hyde](https://avatars.discourse-cdn.com/v4/letter/m/47e85d/32.png) [@Martin\_Hyde](https://boards.straightdope.com/u/Martin_Hyde)\ **Post date:** [October 20, 2014, 10:12pm UTC](https://boards.straightdope.com/t/there-will-be-another-ice-age-true-yes-true-but-when/701561/24 "2014-10-20T22:12:30Z")
> [@GIGObuster](#): > > And yes, climate has changed before, but claiming that it is unlikely that man has altered any climate constant is kinda silly because there is no mechanism that one can propose that can tell us that CO2 has reformed from what it did to the earth in the past; currently the content of CO2 in the atmosphere, in large part as a result of what humans have emitted, has been is at 400 ppm. > > [National Geographic](http://news.nationalgeographic.com/news/energy/2013/05/130510-earth-co2-milestone-400-ppm/) There’s no evidence of anything called a climate constant, is my point, to which this post is non-responsive. ---
**Author:** ![Martin\_Hyde](https://avatars.discourse-cdn.com/v4/letter/m/47e85d/32.png) [@Martin\_Hyde](https://boards.straightdope.com/u/Martin_Hyde)\ **Post date:** [October 20, 2014, 10:15pm UTC](https://boards.straightdope.com/t/there-will-be-another-ice-age-true-yes-true-but-when/701561/25 "2014-10-20T22:15:24Z")
> [@GIGObuster](#): > > Not so. > > [Ice age study delivers blow to global-warming skeptics - CSMonitor.com](http://www.csmonitor.com/Environment/2012/0405/Ice-age-study-delivers-blow-to-global-warming-skeptics) Where did the CO2 come from? > [@wolfpup](#): > > I don’t know what you mean by “climate constant” as that isn’t a scientifically meaningful term. We have certainly altered CO2 very dramatically, and we have taken it out of the narrow range in [which it has existed for a million years](http://upload.wikimedia.org/wikipedia/commons/b/b8/Vostok_Petit_data.svg). Indeed since industrialization we have increased it from the normal post-glacial maximum by a greater margin than its entire excursion from the depths of an ice age to the peak of an inter-glacial. That is a truly monumental change in CO2 forcing with major implications for the future of climate. Yes we have, but that’s not us changing a “climate constant.” Humans can change climate, but they can’t change a “climate constant” because there is no climate constant. > [@](#): > > URL=“[Radiative forcing - Wikipedia](http://en.wikipedia.org/wiki/Radiative_forcing#Forcing_due_to_atmospheric_gas)”]The laws of physics frankly don’t care if you “find it unlikely.” So does gravity cause the Earth to revolve around the Sun or is it the Sun’s mass? You’re confusing mechanism and cause. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 21, 2014, 12:08am UTC](https://boards.straightdope.com/t/there-will-be-another-ice-age-true-yes-true-but-when/701561/26 "2014-10-21T00:08:23Z")
> [@Martin\_Hyde](#): > > Where did the CO2 come from? > > [Ordovician Period | Major Events, Extinction, & Facts | Britannica](http://www.britannica.com/EBchecked/topic/431581/Ordovician-Period/258446/Paleoclimate) > > > [@](#): > > > > Numerical climate models as well as carbon isotope measurements from preserved Ordovician soils suggest that atmospheric levels of carbon dioxide during the period were 14–16 times higher than today. These high levels were driven by widespread volcanic activity, which would have released large volumes of carbon dioxide into the atmosphere. > > Yes we have, but that’s not us changing a “climate constant.” Humans can change climate, but they can’t change a “climate constant” because there is no climate constant. Well, in a previous discussion it was mentioned that some scientists thought that cycles like El Nino were not present in the deep past, but there evidence was found that it was, There are hard to miss cycles that are apparent when looking at the past CO2 records. [http://www.southwestclimatechange.org/climate/global/past-present](http://www.southwestclimatechange.org/climate/global/past-present) > [@](#): > > Figure 2. As ice core records from Vostok, Antarctica show, the temperature near the South Pole has varied by more than 20º F during the past 350,000 years in a regular pattern that constitutes the ice age/interglacial cycles. Changes in carbon dioxide concentrations (blue) track closely with changes in temperature (red) during these cycles, but carbon dioxide levels are now higher than at any time during the past 650,000 years . But what is easy to miss is how gradual those changes were, where the “constant” enters the picture is that those cycles took a very long time in prehistoric times, and that is why most climate scientists are worried when in the blink of a geological eye we are seeing a huge rise in the CO2 content and that warming is following it, in a relative short time the record that behaved like a constant is being changed as we speak. > [@Martin\_Hyde](#): > > So does gravity cause the Earth to revolve around the Sun or is it the Sun’s mass? You’re confusing mechanism and cause. As it was shown before, you were wrong about carbon not being a driver of geological scale climate change. It is a bit more complicated, but even in cases where CO2 does not lead at the beginning, CO2 then takes over. > **[CO2 lags temperature - what does it mean?](https://skepticalscience.com/co2-lags-temperature-intermediate.htm)** > > \When the Earth comes out of an ice age, the warming is not initiated by CO2 but by changes in the Earth's orbit. The warming causes the oceans to give up CO2. The CO2 amplifies the warming and mixes through the atmosphere, spreading warming... > [@](#): > > To claim that the CO2 lag disproves the warming effect of CO2 displays a lack of understanding of the processes that drive Milankovitch cycles. A review of the peer reviewed research into past periods of deglaciation tells us several things: > > ``` > Deglaciation is not initiated by CO2 but by orbital cycles > CO2 amplifies the warming which cannot be explained by orbital cycles alone > CO2 spreads warming throughout the planet > > ``` > > Overall, more than 90% of the glacial-interglacial warming occurs after the atmospheric CO2 increase (Figure 3). The cite has a link to a video that should be seen, with cited published science: [![](https://img.youtube.com/vi/8nrvrkVBt24/hqdefault.jpg "The "Temp Leads Carbon" Crock: Updated") ](https://www.youtube.com/watch?v=8nrvrkVBt24) ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 21, 2014, 12:14am UTC](https://boards.straightdope.com/t/there-will-be-another-ice-age-true-yes-true-but-when/701561/27 "2014-10-21T00:14:47Z")
BTW in that video, Rep. Dana Rohrabacher ® shows why he and virtually all republicans in congress should not be part of any science committee. ---
**Author:** ![Martin\_Hyde](https://avatars.discourse-cdn.com/v4/letter/m/47e85d/32.png) [@Martin\_Hyde](https://boards.straightdope.com/u/Martin_Hyde)\ **Post date:** [October 21, 2014, 12:48am UTC](https://boards.straightdope.com/t/there-will-be-another-ice-age-true-yes-true-but-when/701561/28 "2014-10-21T00:48:40Z")
> [@GIGObuster](#): > > Well, in a previous discussion it was mentioned that some scientists thought that cycles like El Nino were not present in the deep past, but there evidence was found that it was, There are hard to miss cycles that are apparent when looking at the past CO2 records. > > [Home | Arizona Environment](http://www.southwestclimatechange.org/climate/global/past-present) > . I agree if we: 1. Overstate what “found” means 2. Overstate what “deep past” actually means > [@](#): > > But what is easy to miss is how gradual those changes were, where the “constant” enters the picture is that those cycles took a very long time in prehistoric times, and that is why most climate scientists are worried when in the blink of a geological eye we are seeing a huge rise in the CO2 content and that warming is following it, in a relative short time the record that behaved like a constant is being changed as we speak. Why wouldn’t we be worried about man made warming? > [@](#): > > As it was shown before, you were wrong about carbon not being a driver of geological scale climate change. It is a bit more complicated, but even in cases where CO2 does not lead at the beginning, CO2 then takes over. And you miss the point, I never said CO2 wasn’t a mechanism that causes climate change. I said it wasn’t the cause. Mars’ atmosphere is like 95% CO2 and it’s very cold there, and has been for billions of years. > [@](#): > > [CO2 lags temperature - what does it mean?](http://www.skepticalscience.com/co2-lags-temperature-intermediate.htm) > > The cite has a link to a video that should be seen, with cited published science: > > [http://www.youtube.com/watch?v=8nrvrkVBt24](http://www.youtube.com/watch?v=8nrvrkVBt24) By what mechanism does CO2 cause itself to magically increase in concentration in the atmosphere. I fail to understand how a chemical compound can, without any actual cause, suddenly concentrate in the atmosphere. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 21, 2014, 1:25am UTC](https://boards.straightdope.com/t/there-will-be-another-ice-age-true-yes-true-but-when/701561/29 "2014-10-21T01:25:44Z")
> [@Martin\_Hyde](#): > > And you miss the point, I never said CO2 wasn’t a mechanism that causes climate change. I said it wasn’t the cause. Mars’ atmosphere is like 95% CO2 and it’s very cold there, and has been for billions of years. This is not clear at all, so people that causes forest fires with reckless behaviour are blameless because the trees caused it? The current cause of the warming observed has a clear human component, as it was pointed many times before is that humans have released Gigatons of the stuff and altered the quantities that nature could deal with in the carbon cycle. > **[About Berkeley Earth - Berkeley Earth](https://berkeleyearth.org/about/)** > > Todays Challenge Global warming is they defining environmental challenge of our time. The need for quality, accessible scientific data about global warming could not be more urgent. Yet there are few independent sources of historic global temperature... > [@](#): > > From 2010-2012, Berkeley Earth systematically addressed the five major concerns that global warming skeptics had identified, and did so in a systematic and objective manner. The first four were potential biases from data selection, data adjustment, poor station quality, and the urban heat island effect. Our analysis showed that these issues did not unduly bias the record. The fifth concern related to the over reliance on large and complex global climate models by the Intergovernmental Panel on Climate Change (IPCC) in the attribution of the recent temperature increase to anthropogenic forcings. We obtained a long and accurate record, spanning 250 years and showed that it could be well-fit with a simple model that included a volcanic term and, as an anthropogenic proxy, CO2 concentration. We concluded that the record could be reproduced by just these two contributions, and that inclusion of direct variations in solar intensity did not contribute to the fit. > [@Martin\_Hyde](#): > > By what mechanism does CO2 cause itself to magically increase in concentration in the atmosphere. I fail to understand how a chemical compound can, without any actual cause, suddenly concentrate in the atmosphere. Well, then there is ignorance that has to be taken care of. The evidence and the causes where found and investigated back in the 50’s. [http://www.aip.org/history/climate/co2.htm](http://www.aip.org/history/climate/co2.htm) > [@](#): > > The amount of fossil carbon that Suess saw added to the atmosphere was barely one percent, a fraction so low that he concluded that the oceans were indeed taking up most of the carbon that came from burning fossil fuels. A decade would pass before he reported more accurate studies, which showed a far higher fraction of fossil carbon. Yet already in 1955 it was evident that Suess’s data were preliminary and insecure. The important thing he had demonstrated was that fossil carbon really was showing up in the atmosphere. More work on carbon-14 should tell just how carbon was circulating in the planetary system.(30) > > =\>Revelle’s result > > Suess took up the problem in collaboration with Roger Revelle at the Scripps Institution of Oceanography in La Jolla, California. (Some other carbon-14 experts attacked the topic independently, all reaching much the same conclusions.) From measurements of how much of the isotope was found in the air and how much in sea water, they calculated the movements of CO2 (link from below). It turned out that the ocean surface waters took up a typical molecule of CO2 from the atmosphere within a decade or so. Measurements of the travels of radioactive carbon from bomb tests meanwhile showed that the oceans turned over completely in several hundred years (an estimate soon confirmed by evidence from other studies).(31) At first sight that seemed fast enough to sweep any extra CO2 into the depths. > > But Revelle had been studying the chemistry of the oceans through his entire career, and he knew that the seas are not just salt water but a complex stew of chemicals. These chemicals create a peculiar buffering mechanism that stabilizes the acidity of sea water. The mechanism had been known for decades, but Revelle now realized that it would prevent the water from retaining all the extra CO2 it took up. A careful look showed that the surface layer could not really absorb much additional gas — barely one-tenth the amount a naïve calculation would have predicted. > > A supplementary essay on Revelle’s Discovery tells this crucial story in full, as a detailed example of the complex interactions often found in geophysical research. > Revelle did not at first recognize the full significance of his work. He made a calculation in which he assumed that industry would emit CO2 at a constant rate (like most people at the time, he scarcely grasped how explosively population and industry were rising). This gave a prediction that the concentration in the air would level off after a few centuries, with an increase of no more than 40%. Revelle did note that greenhouse effect warming “may become significant during future decades if industrial fuel combustion continues to rise exponentially.” He also wrote that “Human beings are now carrying out a large scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future.”(32) > > As sometimes happens with landmark scientific papers, written in haste while understanding just begins to dawn, Revelle’s explanation was hard to grasp. Other scientists failed to see the point that was obscurely buried in the calculations, and continued to deny there was a greenhouse effect problem. In 1958, when Callendar published a paper to insist once again that CO2 observations showed a steady rise from the 19th century, he noted Revelle’s paper but still confessed that he did not understand why “the oceans have not been accepting additional CO2 on anything like the accepted scale.”(33) Finally in 1959 two meteorologists in Sweden, Bert Bolin and Erik Eriksson, caught on. They explained the sea water buffering clearly — so clearly that during the next few years, some scientists cited Bolin and Eriksson’s paper for this decisive insight rather than Revelle and Suess’s (only in later years was Revelle always cited for the discovery).(34) The central insight was that although sea water did rapidly absorb CO2, most of the added gas would promptly evaporate back into the air before the slow oceanic circulation swept it into the abyss. To be sure, the chemistry of air and sea water would eventually reach an equilibrium — but that could take thousands of years. Arrhenius had not concerned himself with timescales shorter than that, but geoscientists in the 1950s did. > > In the late 1950s a few American scientists, starting with Plass, tentatively began to inform the public that greenhouse gases might become a problem within the foreseeable future. Revelle in particular warned journalists and government officials that greenhouse warming deserved serious attention. The stakes were revealed when Bolin and Eriksson pursued the consequences of their calculation to the end. They assumed industrial production would climb exponentially, and figured that atmospheric CO2 would rise some 25% by the year 2000. That was a far swifter rise than anyone before had suggested. As the New York Times reported in a brief note, Bolin suggested that the effect on climate “might be radical.”(34a) In 1962, a still stronger (although also little heeded) warning was sounded by the Russian climate expert Mikhail Budyko. His calculations of the exponential growth of industrial civilization suggested a drastic global warming within the next century or so. Much more in that book on the history of \*The Discovery of Global Warming \* [http://www.aip.org/history/climate/index.htm](http://www.aip.org/history/climate/index.htm) ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [October 21, 2014, 1:27am UTC](https://boards.straightdope.com/t/there-will-be-another-ice-age-true-yes-true-but-when/701561/30 "2014-10-21T01:27:19Z")
> [@Martin\_Hyde](#): > > Where did the CO2 come from? It came from the carbon sinks that take up CO2 in cooler climates and emit it when the climate warms. > [@Martin\_Hyde](#): > > Yes we have, but that’s not us changing a “climate constant.” Humans can change climate, but they can’t change a “climate constant” because there is no climate constant. No, there isn’t, and I never claimed there was, nor do I even know what you mean by that term. You’re the only one who’s used it here, and it seems to be something you made up. > [@Martin\_Hyde](#): > > So does gravity cause the Earth to revolve around the Sun or is it the Sun’s mass? You’re confusing mechanism and cause. Well, you accused me of being “scientifically stupid” when I talked about the contemporary 100 Ky ice age cycles, which are one of the most important phenomena in recent climate history, as I showed you in the graph I linked. Then you invented something about a “climate constant” that I never mentioned. I assure you that I’m not the one who’s “confused” here. The earth’s geological climate changes have been generally driven by a variety of usually long-term factors that alter the atmospheric carbon content, usually taking place over many millions of years. Within that slow-moving tectonic-scale background, the geologically rapid and relatively large-amplitude fluctuations during the latter part of the Quaternary, occurring over roughly 100 Ky intervals, are what dominate the geologically modern climate and constitute what we refer to as “ice ages”, as shown in that graph. These are the cycles that spawned the weird two-legged species that eventually evolved into _homo sapiens_, and the ecosystem that we thrive on. We’ve now hugely disrupted that cycle by injecting massive amounts of permanently sequestered CO2 from fossil fuels into the active carbon cycle, as I showed [in this graph](http://upload.wikimedia.org/wikipedia/commons/1/1c/Carbon_Dioxide_400kyr.png). The question of “primary cause” is now squarely centered on the radiative effects of CO2 and other GHGs. That’s what matters. [Here’s another graph showing what post-industrial CO2 looks like](http://www.yaleclimateconnections.org/pics/1210_ZHfig2.jpg) relative to the last 10,000 years of the current inter-glacial – a spike going straight up, and rising so fast that it’s now off the scale from the graph that was made in 1995. And **that’s** why the radiative effects of CO2 (not to mention other GHGs like CH4 and NOx) is of primary concern in post-industrial climate change. ---
**Author:** ![Kimstu](https://avatars.discourse-cdn.com/v4/letter/k/ecd19e/32.png) [@Kimstu](https://boards.straightdope.com/u/Kimstu)\ **Post date:** [October 21, 2014, 5:40am UTC](https://boards.straightdope.com/t/there-will-be-another-ice-age-true-yes-true-but-when/701561/31 "2014-10-21T05:40:35Z")
**Martin** , in this discussion you are somewhat in the position of a man responding to the question “When’s the next mail pickup?” with a rather fuzzy recap of the history of the Postal Service and speculation about the possibility of its ultimate disappearance as email takes over. All of which may be very interesting but is totally off-target. The OP was very clearly asking about the next recurrence of the same periodic phenomenon that **wolfpup** is referring to by “ice age”. And anthropogenic CO2-driven changes in the present “sliver of geologic time” are definitely crucial for that. [Previous page](https://boards.straightdope.com/t/there-will-be-another-ice-age-true-yes-true-but-when/701561.md?page=1)