Right now the earth is in an ice age. Luckily, we’re in a particularly warm bit known as an interglacial. People talk about long off events and threats often; the once in 10,000,000yr supervolcano/asteroid/whatever, and even to a degree, make plans to avert or alleviate them. During this ice age, the percentage of the earth covered in ice has varied on a cycle, and the ice is due to return pretty (in geological terms) soon. We even have significant sized stone constructions dating back to the end of the last ice age. This is something that happens on a timescale within human scope, and something that would be a major disaster. Let’s talk about how big a disaster.
A significant percentage of the biggest, most historically significant cities in the world would probably be abandoned, then destroyed, ground into dust under miles of ice. Even the large part of the world population that wouldn’t be under ice would cool significantly, bringing seasonal snow and ice to large, relatively poor populations who would likely be unable to afford the needed heat. Global sea levels would drop, altering ocean currents, rendering current major waterways unusable. The amount of land crops could be grown on would drop, and crops that would still exist would be less productive.
So onto the questions.
When is the next glacial period coming?
What can we do that might prevent it?
Will global warming stop it/end the current ice age?
Good point. I’ve wondered this too. When you look at the graphs of the last million years or more, the interglacials are not that long and this one seems to be going on a bit too long.
The other point there in the graphs is that changes can be abrupt and unpredictable. Plus, we haven’t hit the max of the last several ages yet…
(Larry Niven’s Fallen Angels is based on the premise that it’s only human global warming that is holding us back, and thanks to all those Prius cars we’ll have glaciers in North Dakota by 2100AD.)
All the global warming in the world is puny compared to what Mother Nature may decide to throw at us. Not just mile-thick glaciers across the continents, but also warming episodes where quasi-cold-blooded dinosaurs migrated up and down the balmy seashore of Texas, Wyoming, Alberta and Alaska. Whatever the sun decides to do or not, we are helpless.
Sorry, but you are just plain wrong in that regard; according to all accepted theory, the Sun was cooler when dinosaurs roamed the Earth (about 1% per 100 million years into the past) and greenhouse gasses were much higher, that the main reason why it was warmer (otherwise, the Earth would have been frozen for the first billion years or more since the Sun was up to 40% dimmer than today, and actually, that did happen when plants evolved and produced an oxygen-rich atmosphere, and more than once). The current period is cooler than the dinosaur era simply because plate tectonics have reduced the amount of CO2 produced by volcanoes (over millions of years).
That aside, it is highly likely that the current interglacial won’t end anytime soon (some even think that the next Ice Age should have already started but early human agriculture was enough to prevent it from happening); first, we need to see increases in summer snow and ice cover, which is the opposite of what is actually happening. Also, the Earth is already pretty close to an insolation minimum, and it will switch from cooling to warming in the next thousand years or so (absent human contributions of course):
I don’t want to hijack this thread, but could this be a benefit to human induced global warming if it is true. I have never seen a chart of any scenario no matter how bad that didn’t have some positives on one side and negatives on the other even if they aren’t balanced. There has to be some benefits to global warming somewhere. Could this be one and, even not, are there others?
Hmmm… I’ve heard the Malkovich cycle theory, but a quick examination of the graph linked (blue, top is temperature) shows only a minimal correlation if any between temperature variation and 25,000 year cycles. If anything, the cycles seem to be about 100K to 120K and fairly erratic, not astronomically precise. Plus, that does not explain why the glacial interludes come and go over the last billions of years, if the situation is a very regular cyclical change in insolation plus an increasing solar output.
That also does not account for phenomemon like Maunder minimum/little ice age, Sporer minimum, Wolf minimum, Medieval maximum, etc. The graph suggests that in the last half million years at least, the temperature has been all over the map - the only guarantee being that the present balmy interlude will give way to 70,000-plus years of much chillier teperatures; while the dinosaurs definitely roamed the tropical forests of the arctic, 40% less illumination or not.
I suspect, with minimal astronomy background, that the sun is a lot more variable than the professionals would like to believe.
Just a question here as I don’t know the technical answers to the OP…isn’t the sun, as it burns through it’s hydrogen fuel, supposed to get hotter as time goes by? I thought as stars aged they got hotter, and eventually our sun will become a red giant (in a few billion years, before eventually cooling off to become a white dwarf), and will actually expand to eventually engulf the space where the Earth currently resides.
I’m sure that solar variations will still cause ice ages in the future (I doubt AGW will prevent them…if the sun varies by even 1%, from what I understand, we’ll get an ice age again, and that’s something that seems to happen fairly regularly over the course of geological history), but overall I thought the sun was getting hotter. Is that correct?
And just why do you think all of those scientists are wrong? If anything, some think (example) that even recent variation has been a lot less due to changes in reporting sunspot numbers (leaving some clear discontinuities). the Little Ice Age can also be fully explained by volcanoes alone, no need to include the Maunder Minimum (which also started after the LIA did), which, according to the first link, was probably no deeper than the most recent minimum, the lowest in 100 years and following several decades of decreasing activity, yet global temperatures are increasing, never mind the claims of cooling on impossible scales (Skeptical Science also has answers to other questions so you might want to look at that further).
As far as I know, no one knows for sure when there will be a new glacial period. Some theories hold the answer is “never”; that we are heating the Earth to the degree that it will permanently (on a human time scale at least) enter a new, warmer climatological era. Whether that’s good* or bad no one knows since humanity has never experienced such a climate. It could mean anything from just having less land, to the destruction of civilization (in the wort case scenarios like an unstable climate making agriculture impractical, or continent-wide “hypercanes”).
*In the long run; in the short it’s pretty much guaranteed to be bad since the transition period will disrupt agriculture and such
Yes. In fact, barring human/posthuman intervention it’s expected that long before the Sun goes red giant, Earth will heat up to the point where it’ll undergo a runaway greenhouse effect and end up like Venus.
