Good program on the History Channel last night. Helps to put climatic variation and global warming in perspective.
Airing again next Saturday afternoon
Airing again next Saturday afternoon
Little Ice Age
- Thread starter Uncle Bob
- Start date
archhealer
SOC-12
I saw that. I find it interesting how they hint that industrial developement has staved off an ice age for a long time, but it could let go, at any time. Makes for an interesting thought. If people aren't paying attention to it, how bad woudl the ice age that's been held up till TL12 or 13 be?
I didn't quite take that away (although that was the theme of ⌧elle & Niven's Fallen Angels). It may take a few more decades for global warming to shut of the Atlantic Conveyer, and greenhouse gasses may trivially hasten that day. But once the conveyer is broken I doubt we can influence the ice age.
I think it is reasonable to conclude that TL 6-8 human emmissions are a trivial component of climate change, though. By TL 12-13 we can use very large mirrors to influence climate, or build very large fusion power plants, or just move everyone elsewhere.
I think it is reasonable to conclude that TL 6-8 human emmissions are a trivial component of climate change, though. By TL 12-13 we can use very large mirrors to influence climate, or build very large fusion power plants, or just move everyone elsewhere.
archhealer
SOC-12
Like I said, the key would be if people weren't paying attention; or, alternately, if a plantet/nation on a planet were racing to industrialize and 'catch up to' or surpass neighbors, they could really do some damage this way, and bury themselves in ice.
I think one should try to keep ice ages in perspective. Contrary to common sci-fi frozen apocalypse stereotypes, they don't bury anyone unless the person waits patiently in the same spot and has a very long life.
The full temperature change takes a short time for geology but a very long time for humans. The building of an ice sheet after the initial drop takes even longer time and you need the sheet for the feedback. The time it took for the last great ice sheet to reach Berlin is several times longer than the entire human post-ice-age history.
/Pompe ( LiveJournal )
The full temperature change takes a short time for geology but a very long time for humans. The building of an ice sheet after the initial drop takes even longer time and you need the sheet for the feedback. The time it took for the last great ice sheet to reach Berlin is several times longer than the entire human post-ice-age history.
/Pompe ( LiveJournal )
archhealer
SOC-12
I meant bury figuratively; as in, bury the world. Not the people. I'm aware that if you move a couple of feet a year, you're not likely to get buried in ice
Fritz_Brown
Super Moderator
Though I've known a few who certainly wouldn't move further than that if the fridge were close enough to the lounger and the remote never needed new batteries!Originally posted by Archhealer:
I meant bury figuratively; as in, bury the world. Not the people. I'm aware that if you move a couple of feet a year, you're not likely to get buried in ice
GypsyComet
SOC-14 1K
Because Venus is under a "run-away" greenhouse effect. Too much atmosphere of the wrong mix, too close to the Sun.
By comparison, Earth has swung back and forth from hothouse to icebox over and over in it's long life. The exact triggers for a swing towards an extreme are unknown, and what looks like a trigger for one extreme may in fact be a trigger for the other...
By comparison, Earth has swung back and forth from hothouse to icebox over and over in it's long life. The exact triggers for a swing towards an extreme are unknown, and what looks like a trigger for one extreme may in fact be a trigger for the other...
One thing to think about:
If, for example, the current shuts off: Anchorage summer temps will drop from their nice 70°-90° F range down to 50°-70°. Winter temps would drop from 0°-30° down to -20° to +10° F. THe normal january melt off of 2-4" would cease. We'd have snow falling until may. It would start in august or september. This can happen during an el nino, when the current pulls away from the Alaska coast.
The rate of glaciation advance would be fairly slow; the development of persistent ice fields can be FAR faster. At present, Anchorage has snow 8 months of the year, and snow coverage 6 months. 10 degrees cooler, and that could reach 9 and 8, respectively. 20 degrees cooler, and it could easily reach 12 and 9, as the snow fails to melt off before the new snow falls. This radical difference has to do with ground-freezing, and thermal battery effects of topsoils. (Last summer, we still found patches of snow in late may and early june. We had snow in september, but it didn't stick...)
These ice fields would not be glaciers, per se, for the first several years. But, if they start to accumulate, the addition of half an inch of depth per year can make piles grow in surface coverage by feet per year.
If, for example, the current shuts off: Anchorage summer temps will drop from their nice 70°-90° F range down to 50°-70°. Winter temps would drop from 0°-30° down to -20° to +10° F. THe normal january melt off of 2-4" would cease. We'd have snow falling until may. It would start in august or september. This can happen during an el nino, when the current pulls away from the Alaska coast.
The rate of glaciation advance would be fairly slow; the development of persistent ice fields can be FAR faster. At present, Anchorage has snow 8 months of the year, and snow coverage 6 months. 10 degrees cooler, and that could reach 9 and 8, respectively. 20 degrees cooler, and it could easily reach 12 and 9, as the snow fails to melt off before the new snow falls. This radical difference has to do with ground-freezing, and thermal battery effects of topsoils. (Last summer, we still found patches of snow in late may and early june. We had snow in september, but it didn't stick...)
These ice fields would not be glaciers, per se, for the first several years. But, if they start to accumulate, the addition of half an inch of depth per year can make piles grow in surface coverage by feet per year.
In order for a snow field to become a glacier the ice/firn should be several tens of meters thick in order to compress the fallen snow and make the ice move. The exact minimum is a bit debatable and depends on other things too, but lets stick with a low estimate of 30 meters. (For a plateau ice, I'd be more inclined to think 100 meters or so).
So by the half-inch estimate, it would take 2000 years to get a glacier in Anchorage.
So by the half-inch estimate, it would take 2000 years to get a glacier in Anchorage.
GypsyComet
SOC-14 1K
...except that as the climate changes, so do the weather patterns. Anchorage could then be getting more snowfall per year, with no significant melt in between. It could also get less snow per year but get colder, meaning a transition to full-on arctic permafrost desert. It would also have issues with its name at that point, as falling sea levels would render the waterways non-navigable.
Anchorage is likely to remain "wet" even with significant changes; it's the bottom of a pentagonal bowl, of which 3 sides are mountains, the other two coastal and aimed southwest. Maritime air masses are likely to drive right up the funnel.
Also, most of Anchorage is terminal moraines of receeded glaciers. It once was covered by glaciers, about 8-10KYA, according to the USGS. Judging from the strata revealed, it's likely they were exceptionally fast moving. ANd there are many glaciers in the anchorage bowl currently... literally several dozen small ones. (Many have vanished in the last 10 years...)
At the moment, snow accumulation is about 3"; another 1/2" of hoar-frost, in downtown Eagle River (About 5m from the river delta, and 0.1mi from the highway); frost accumulation is jagged planes of up to 1cm².
Also, most of Anchorage is terminal moraines of receeded glaciers. It once was covered by glaciers, about 8-10KYA, according to the USGS. Judging from the strata revealed, it's likely they were exceptionally fast moving. ANd there are many glaciers in the anchorage bowl currently... literally several dozen small ones. (Many have vanished in the last 10 years...)
At the moment, snow accumulation is about 3"; another 1/2" of hoar-frost, in downtown Eagle River (About 5m from the river delta, and 0.1mi from the highway); frost accumulation is jagged planes of up to 1cm².
archhealer
SOC-12
You know, just to keep in mind, weather is very hard to accurately predict. The Farmer's Almanac is usually pretty good, but this winter it was totally off. The Weather Channel is right about 65% of the time. And that's way up from where weather predictions used to be.
That being said, I've had it snow, In MA, USA, on my birthday party. In June. Granted, only once, but it was funny. I've also seen it snow as much as two meters accumulation in three days, in both MA and NH on two seperate occasions.
So, if the weather tweaked just a little bit, we could easily wind up seeing that kind of weather more often, and as already stated, in parts of the world where it may not melt significantly. So 100 meters of snow may only take 20 or 30 years to accumulate. Of course, the other thing to remember is once glaciers start forming/moving around more than they already do/are, they themselves will dramatically change the weather patterns. Large masses of water, be it solid, liquid, or vapor, are a major driving force for weather in general.
That being said, I've had it snow, In MA, USA, on my birthday party. In June. Granted, only once, but it was funny. I've also seen it snow as much as two meters accumulation in three days, in both MA and NH on two seperate occasions.
So, if the weather tweaked just a little bit, we could easily wind up seeing that kind of weather more often, and as already stated, in parts of the world where it may not melt significantly. So 100 meters of snow may only take 20 or 30 years to accumulate. Of course, the other thing to remember is once glaciers start forming/moving around more than they already do/are, they themselves will dramatically change the weather patterns. Large masses of water, be it solid, liquid, or vapor, are a major driving force for weather in general.
P
Pickles
Guest
Pompe,
They can advance or recede far faster than that. During the last ice age, Britain went from a climate essentially the same as the one it has now to an ice sheet about a kilometer thick in ~100 years.
May I suggest the many recent geology books written John McPhee? He's a fine author who can keep your interest no matter what the subject matter.
Have fun,
Bill
Those are all amazing concepts, but I think you're "right", at least in the Traveller sense.
I've assumed that the Imperium has some sort of terraforming ability, and can warm up, cool down, or hydrate worlds (in the habitable zone I suppose) as needed. That could help explain why many worlds seem rather pleasant but have horrible primaries (luckily my disbelief suspenders are very loose and don't snap well).
And I've also assumed that TL12 has the ability to move hundreds of thousands of people over a short period of time (for some definition of 'short') if need be -- though I suspect that kind of action is rare and expensive.
Well, the magnetic North Pole has been wandering around a lot in the last couple of decades. Enough that many military maps can't be used with precision without corrections. If the poles flip we lose the Van Allen belts temporarily. The Solar Wind won't peal off the atmosphere very fast, but it will fry all the commo/GPS satellites and make cave living popular.
It has happened before.
It has happened before.
It all seems like a real good reason for a ghost world; lots of abandoned buildings and mummified bodies, with no apparent reason for death ... a hard lesson in the risks of frontier living.
