ice age?

[vanilla]

Just read this book written a few years ago.
The author says a sudden ice age is coming; thats what killed the dinosaurs.
They come every 11,500 years, and the last one happened 11,500 years ago.
I thought we were having global Warming?

[Enola_Straight]

Ice requires snow…
Snow requires precipitation…
Precipitation requires moisture…
Moisture requires evaporation…

And evaporation requires heat.

This may be simplistic, or even absolutely wrong, but
its something to think about.

[Mirage]

IANA Earth Scientist, but that claim sound a little kooky. Next I would expect to hear that when all of the ice melted, it flooded the earth and Noah was the only one to ride it out. Also, I thought that the last ice age was more like 30,000 years ago…

I can’t find the cite, but I remember seeing a graph of the average global temperature over the last million years or so (gathered from geological data). It shoots up and down between ice ages and warming periods. The funny thing is that the last 10 or so thousand years have been remarkably level, which people think is due to the major ocean currents like the Gulf Stream.

I’ll see if I can find the cite…

[Phobos]

vanilla - I’d say that the author does not share the view of the majority of the scientific community. First off, it is believed that an asteroid/comet killed the dinosaurs. Ice ages do come and go, but I don’t think we can predict the next one. I think the last big ice age was something like 40,000 years ago, wasn’t it? Over the past century, the Earth’s average surface air temperature has increased by 0.5 C (source: National Geographic, May 98)

Enola - Ice requires snow? Does it snow in your freezer? Snow requires precipitation? Snow IS precipitation. Anyway, I’m not sure what your overall point is…are you saying that warming may cause ice ages?

[Phobos]

NOVA says this…

Ever since the Pre-Cambrian (600 million years ago), ice ages have occurred at widely spaced intervals of geologic time - approximately 200 million years - lasting for millions, or even tens of millions of years.

Hmm…perhaps the OP refers to The Milankovitch Theory about global temperature variations due to the wobble of the Earth’s axis of rotation?

Maybe we need to define “ice age” (short term cooling like the mini ice age a few hundred years ago or long term cold climate like the NOVA link is talking about).

[Mirage]

Here’s a NOVA Online link that does some good explaining…

During the present ice age, glaciers have advanced and retreated over 20 times, often blanketing North America with ice. Our climate today is actually a warm interval between these many periods of glaciation. The most recent period of glaciation, which many people think of as the “Ice Age”, was at its height approximately 20,000 years ago.

It even hints that the ice age drove the deforestation of Africa which drove our ancesters out into the plains to learn to throw rocks and spears instead of their own kaka.

[DrFidelius]

Who says that the last glaciation has ended? Huge areas of the Earth are still under ice and permafrost. Just because the parts most of us live in are warm enough for enough of the year to allow agriculture doesn’t mean that an Ice Age has ended.

We have a long way to go before average global temperatures get back up to the normal levels of the Tertiary. And even further to go to get back to Mesozoic norms.

[jack_ss]

I saw a program on…I think it was the Discovery Channel, or it could have been TLC or PBS a few months ago. In this program more than one climatologists (is that even the word?) stated that global warming will melt significant amounts of the global ice caps, resulting in changes to the ocean temperature, resulting in disruption of deep ocean currents, which could eventually result in another ice age in 500-1,000 years. That’s the gist as I remember it, I’ll have to do some research to find an article, name some of the scientists.

[jack_ss]

Discover Magazine’s website
had this to say:

According to a theory worked out by climatologist James Walker of the University of Michigan and other researchers, chemical weathering could have acted as a planetary thermostat to keep Earth from boiling over. As Earth warmed under its CO2 blanket, the evaporation of water from oceans increased, thereby increasing rainfall. The more rainfall, the more chemical weathering. The more weathering, the greater the pace of CO2 distillation out of the atmosphere and into the ocean floor. The less CO2 in the atmosphere, the cooler the planet’s temperature. This weathering cycle, say Walker and company, saved the globe from cooking in its own greenhouse.

which pretty much agrees with Enola Straight.