Was watching a show on the Science Channel tonight and one of the people on the show said something like ‘one thing is true…there will be another ice age sometime in the Earth’s future’. It got me wondering…what affect, if any, will humanity have on future ice ages (the answer to the question of whether we will have an ice age in the title, at least as far as I know, is yeah…it’s true. There will be another ice age on the planet some day). What with global warming, it doesn’t seem likely any time soon, but in geological scales, I know we are really in the interim period between ice ages. Assuming humans keep burning fossil fuels though, will this throw off the cycle, push it back or not affect it at all? That’s the actual question I wanted to ask. Since I suppose it might be controversial or debatable, I figured I’d put this here instead of in GQ.
It’s quite possible there will never be another Ice Age after this one - technically we are in an Ice Age, during an interglacial period. The Earth spends a minority of its time with an Ice Age climate like ours (20% IIRC), and the Sun is slowly warming; once we push the Earth into a new warm period it may never go back to an ice Age climate before the Sun warms enough to cause a runaway greenhouse effect and turn the planet into another Venus.
The sun is getting bigger and brighter, but not much hotter, we probably have plenty of time for another major ice age in the next few hundred million years. Right now, the earth’s wobble is closing the tropics together (thus, shrinking the arctic/antarctic circles) by something close to a second each year – this is a 40Ky cycle, not sure where we are in it, but it seems to me it would ultimately have some measure of a cooling effect.
An informed answer to that question has to distinguish between long, tectonic-scale geophysical changes that take tens of millions to hundreds of millions of years to play out, versus the relatively short-term (geologically speaking) glaciation cycles that have been occurring in the geologically modern era. This is markedly defined by the mid-Pleistocene transition that began about 1.2 million years ago and led to the period of modern glaciation cycles that have been occurring on roughly 100K year intervals ever since. The remarkable thing about this geologically modern period we are in is that it’s characterized by CO2 varying in a narrow band between 180 and about 280 ppm. It’s never been higher than 300 ppm, at the peak of inter-glacial warm periods, and always well below 200 ppm during ice ages.
Now, with that in mind, look at where it is today. And we got there in a mere blink of an eye, geologically speaking, and it’s trending higher every year and every decade.
I suspect that we will not have an ice age as long as humans inhabit the Earth and are sufficiently technologically advanced to avoid it. We’re nearly there now: heck, we seem to be doing our best to make sure it goes the other way.
Is it possible that conditions could exceed the amount of available or producible CO2 or other GHG? Even if so, we could suspend huge mirrors that allow the Earth to gather more sunlight.
I strongly suspect that in the not-too-far future, we will be tinkering quite a bit with the climate. For example, I bet we won’t control GHG sufficiently to avert an enormous crisis, so instead we’ll use stopgap methods like injecting sulfates into the atmosphere. This’ll probably be too little too late to avoid the most serious consequence of climate change: sea level rise. But as long as we can manage to keep civilization going during the ensuing series of crises, I bet we’ll learn enough to keep the needle in the green zone, for the most part. With lots of unintended consequences, and serious political issues.
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! Oh boy! Maybe THAT could lead to an ice age! I hope we’re not that stupid, but at present, the evidence is in favor of stupidity.
Der Trihs is both right and wrong. He’s correct we are still technically in an ice age, which is strictly defined as an age in which there is any polar ice at all. This contrasts with other ages in which there is no polar ice.
Conditions vary dramatically in ice ages, from true “snowball Earths” to the conditions in the Pleistocene that Early Modern humans lived under (large glaciation and difficult life if you go too far north and south, but decent living elsewhere.)
Right now we are technically in an interglacial period, which is a period within an ice age during which glaciers recede and basically things get a lot warmer than during colder parts of the ice age.
Where Der Trihs is wrong is in suggesting we won’t see another ice age. I don’t think that’s an reasonable expectation. The Sun is getting hotter, and we do in fact know that at a certain point in the next 1bn years (thoughts suggest around 500m years from now) it will be hot enough that all water on Earth boils off. By that point of course there will never be another Earth ice age. But 500m is a long time, even 100m is a very, very long time. And the changes that take the Earth from ice age to not-ice age and back tend to happen fast enough relative to that span of time it’s reasonable to assume we’ll see this one end and another one or even two come again before things get so warm we never have an ice age again. Especially since it’s kind of fuzzy as to the timing of the solar warming leading to situations like that, the estimates literally range from 500m-1bn years from now, which is a tremendous range suggesting vast uncertainty.
Ah-HA! So you are admitting that global warming is NOT caused by humans and that Al Gore and his sort are just liberal scare-mongers without a scientific foot to stand on!
d&r
Okay so we’re in an ice age during a temporary warm period. Knew that. Glaciation must return, otherwise we’re not in an ice age. If AGW prevents a return to glaciation, then the ice age is over. What criteria are there for scientists to officially declare our current ice age to be over?
Most climate projections are for a century ahead. Are there longer-range forecasts?
In order to return to Pleistocene climate, greenhouse gases will probably need to return to Pleistocene levels. This webpage is about ocean acidification but happens to have a graph projecting CO2 levels through the year 2500. In an optimistic scenario (CO2 peaks at 500 ppm in 2060), CO2 returns only to today’s already-high level by 2500. Are there other papers with longer-range graphs?
But even if CO2 returns to Pleistocene levels, is it clear glaciation will resume? The albedo of Earth’s ice cover is very important to attaining low temperatures. If the ice cover is substantially diminished during the present warming, how long will it take to recover?
I’ve wondered about the same question as OP; surely there are papers trying to predict at least a few thousand years into the future, but I see no cites in the thread. Help?
For all year-round deposits of ice to vanish is one, I understand. As long as there are polar ice caps, we’re still in an ice age.
Here’s a cite for an exceptionally long interglacial in the future, even disregarding the effects of anthropogenic global warming;
A Berger, M Loutre, An Exeptionally long Interglacial ahead
http://www.climate.unibe.ch/~born/share/papers/eemian_and_lgi/berger_loutre02.sci.pdf
But in th even longer term, the natural trend for carbon dioxide in our atmosphere is downwards, so in a few tens of millions of years we might enter a permanent ice age. This will be compounded by the fact that plant growth will be inhibited, raising the albedo of the land surface slightly.
Our planet could remain cold until the gradually warming Sun (mentioned by Der Trihs) melts the ice and our would becomes permanently hot and desertified. Some life might adapt to this environment, but unless humans or their descendants can ameliorate this somehow, the Earth will be inhospitable to our species.
Another factor in the earth’s albedo may be cloud cover. Clouds tend to be white-ish when viewed from space. Increased global temperatures would almost certainly be accompanied by more water vapor in the air, a lot of which would form into highly reflective clouds. This could mitigate temperature increase, assuming the clouds reflect a lot of the higher-frequency light that carries more energy. But, of course, the non-cloudy water vapor in the air traps the heat that does get through, so how it balances out overall is not exactly clear.
(I know you’re kidding) 
the Sun is getting hotter in the large view of things, but of course we’re talking millions of years. It doesn’t significantly explain any recent phenomena, that I’m aware of.
I don’t believe this to be accurate. For one there are still glaciers, and ice ages are not defined by glaciation or lack of glaciation. My understanding is the definition is simple: if there is presence of (summer?–I think if it’s not year round that means no ice age) polar ice, we are in an ice age. There have been many times in Earth’s history when there was no polar ice at all. So when all the polar ice is gone we would no longer classify our current age as an ice age.
It’s quite possible that if you combine two things: a natural interglacial period and human warming, you could unnaturally push the Earth out of an ice age. I doubt that any amount of human warming could have pushed the Earth out of an ice age back in the Pleistocene, but of course since so much of the earth was covered in glaciers we would have so little land to conduct our activities on that lead to CO2 and other greenhouse gas release that we’d not be emitting near as much. It’s also questionable if the colder glacial period in the Pleistocene never ended whether or not we’d even have modern civilization versus being stuck in longer term HG status.
I’ve often wondered about things like that, and maybe because I’m not a scientist and maybe because I lack access to the right databases of research articles I’ve never found an answer (and I have looked.) But one thing we do know is some “extraordinary” events can cause precipitous / unnatural cooling and there are things like algal blooms which can get out of control and rapidly decrease CO2 in the atmosphere–I believe we’ve known of that to happen before. So I think it’s probably hard to predict. I think unless something extraordinary happens the consensus would be we wouldn’t return to Pleistocene climates for a long, long time.
I suspect if we get our emission under control and say, in the year 3000 Earth starts to naturally drift back to a glacial period we’d probably use all we learn about climate in the intervening 1000 years we could probably try to artificially stop that from happening (maybe intentional ramping up of CO2?)
The so-called “current ice age” is really irrelevant to the present discussion and just confuses the issue – the earth entered a relative cool phase and the Antarctic glaciated about 34 million years ago. The meaningful concept of “ice age” is the geologically rapid fluctuations that have been occurring in the Quaternary period starting 2.58 million years ago, and most particularly the fairly regular ~100 Ky cycles that have characterized most of the past million years – the context in which we are now in an inter-glacial warm period.
These are important because, regardless of what initially triggers them (Milankovitch cycles are the most accepted theory), they are primarily driven by CO2, which moves from the atmosphere into the cooling oceans and terrestrial carbon sinks to amplify cooling and drive ice ages, and the other way triggered by Milankovitch warming to end them. During this period it’s only varied in the narrow band between about 180 and 280 ppm, as I mentioned before. The fact that this primary driver of climate is now at 400 ppm and climbing tells us that the possibility of another ice age under these conditions – barring some unexpected major climate event – is nil. And it’s not just the atmosphere that’s affected, it’s also carbon sinks like the oceans.
The real question isn’t whether we can have an ice age under present conditions – the real question is the extent to which we’ve permanently altered the carbon cycle and precipitated long-term feedbacks like melting polar ice and permafrost, even if we stopped burning all fossil fuels tomorrow. It’s possible that the ice age cycles of the last million years may never be the same again. It’s been suggested that we are now in an entirely new geological era that should be called the Anthropocene – the climate of man.
No, the Sun getting hotter is just solar warming. Totally different issue which Fox News hasn’t caught on to… yet.
Higher temperatures certainly result in more water vapor and therefore a positive feedback, but that doesn’t necessarily translate into higher relative humidity, and any possible link to cloud formation is even further removed.
Indeed when Lindzen argued for his “iris hypothesis” of self-limiting warming, his argument was that tropical warming would reduce cirrus cloud formation, and – because high-altitude clouds actually have a positive effect on warming – that their reduction would create a negative feedback . This hypothesis has been pretty much discredited, though.
Clouds are still a complex and sometimes controversial subject with both positive and negative influences, but the general consensus is that on balance they’re not likely to have much impact on climate in either direction, whereas reduced albedo due to surface ice cover decline is already a huge factor in Arctic amplification.
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. If a large enough comet hit Earth tomorrow man would be gone and I suspect in a few thousand years little to no climatological trace would remain–but some life would. 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 also find it confusing when you say scientifically stupid things like “ice age cycles of the last million years.”
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.
I heard it was Thursday next week…
Seems to me that he was writing like they do in geology texts.
But AFAIK, most of the sources out there do talk about ice ages that took place in the previous 500 million years, if one takes into account the billions of years of the earth then I do not see much of a problem on what wolfpup said.
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.