It’s the strangest thing. First, the summers seem to be getting hotter and hotter. This is supposedly due to the infamous Greenhouse Effect–a theory I heartedly endorse, BTW.
Then, about 5 yrs. ago I believe, the summers started being unusually mild and pleasant–in the non-South part of the U.S., in any event.
My question, then, is a two-parter. Are we going thru another Ice Age? I know we are certainly between them in any event. And when will the next ice age be? And I guess I could add to that, for good measure, what causes them in the first place? Is it due to sun activity, like they used to say?
Going through a Wet Age here. Rained every day this week. Going to start to think its Seatle pretty soon.
All kidding aside I would venture to guess that nothing is amiss with the weather. It does not follow any set pattern, and when It seems that it is, its temporary. Alot of factors determine the climate of the seasons. It may seem that the summers are more mild, but in reality it falls within the average yearly temparature spectrum. (In the last 100 years it was a High of 80 deg with a Low of 65 degrees in June 8 different years…etc)
Hope that makes sense.
IMHO you are not going to have a new ice age if we are in a period of global warming (see causes of ice caps). I’m not that sure that we know everything we need to know simply because we have not been keeping accurate records very lone. Scientists are now investigating tree rings, ice cores and other means of looking into the past, but those aren’t the same. Some scientists think that for the last 100 years or so we have been living in a period of stable weather and that possibly we are going out of that period. Who know?
As to possible causes of an ice age, there are four:
[ul][li] changing continental positions [/li][li] uplift of continental blocks [/li][li] reduction of CO2 in the atmosphere [/li][li] changes in the Earth’s orbit[/ul][/li]
But don’t give up hope there is still a chance for a new ice age. Probably not in our lifetime, though.
I had read once (I think it was an Isaac Asimov book) that the early symptons of an Ice Age are NOT a lowering of overall temperature, but the combination of warm, moist winters (more snowfall on the ice packs) and cooler, cloudier summers (less melting of the ice packs).
Actually that isn’t totally true… Global warming could end up shutting down the Gulf Stream, which would lead to a much colder age, especially in Europe. This would lead to catastrophic effects on the world, and would be deemed an Ice Age, even if really wouldn’t fit.
From: Neil Roberts (1989) The Holocene: An Environmental History. Oxford: Basil Blackwell Ltd. p. 42-43.
In short, we are and have been in an “Ice Age”: in terms of geologic history (especially just since the Cretaceous), it’s about as cold now as it’s ever been (the late Precambrian “showball Earth” hypothesis notwithstanding). However, for the past 10,000 years (the Holocene), we’ve been in an interglacial cycle rather than a glacial cycle. During the Pleistocene (~2 million years to 10,000 years ago), there were three or four interglacials; the Holocene simply represents the most recent (which would make it the fourth or fifth overall).
Interglacials are warmer periods that last(ed) 10,000 years or more–and perhaps as many as 20,000 years. Shorter intervals (<1000 years) of cold (e.g., the “Mini Ice-Age”) or warmth that occur during glacial or interglacial cycles are called stadials and interstadials, respectively.
I’m behind the “still in an ice age” argument. Technically, according to a geodicist (sp) I saw speak at my school, an “ice age” is anytime during the Earth’s history that Glaciers exist on the surface. We go back and forth between these periods, so this one is still on going. As long as have polar ice caps, we’re in an ice age.