A New Ice Age?

barakn writes "Scientists have savaged the new movie The Day After Tomorrow, which depicts global warming causing a new ice age and freezing New York solid. The movie follows on the heels of a report to the Department of Defense in February, written by two guys who are not climatologists, about the implications of global warming triggering the growth of ice sheets in the northern hemisphere. There is a plausible theory which suggests that melting ice may release enough fresh water to halt circulation of warm water from the Gulf Stream, thus significantly cooling Europe and the east coast of North America. Note that this theory depends on melting ice, not growing ice, which may be one reason scientists find the ice age scenario so hard to swallow. New satellite evidence suggests a part of this circulation may already be slowing down. Those on the North American west coast will not have to worry about ice sheets, but changes in Arctic ice could mean the western drought will be permanent. For those of you who would rather do something before it's too late, iron seems to work, but the long-term ecological implications are still unknown."

Comments

Re:Wait... so you're telling me...

[Teppy]

Scientists are up in arms because this movie was written by paranormal talk show host Art Bell and alien abductee Whitley Strieber.

Aren't we still in an Ice Age?

[Anonymous Coward]

IIRC, the historic/geologic average temperature of the Earth over it's 5-billion or so years had been something like 72 degrees F.

Today, it's like 59 degreees F.

If that recollection is true, then we're still in an "Ice Age" and should expect the world to be getting warmer if the "Ice Age" is in fact coming to an end.

Sorry if this doesn't fit into the "human == BAD, all_natural == GOOD" paradigm, but getting struck by lightning or eaten by a lion does fall into the "all_natural" category too...

Re:Aren't we still in an Ice Age?

[sparks]

Absolutely correct, we are at present still in an ice age which has lasted for about four million years, with (geologically) brief "interglacials" of around 10,000 - 20,000 years every 140,000 years or so.

We are in one of one of those interglacials now, and in fact it has lasted 18,000 years so far - so it's not at all crazy to start looking for signs of the end of it.

This is not the first ice age; there one approx 600 million years ago; another 450 mya; another 300 mya. They each lasted at least a few tens of millions of years. This ice age is young and will likely exist for many millions more years. During this whole time, we can expect the glacial and interglacial cycle to continue.

There are some important points everyone who discusses climate should be aware of:

For most of the history of the Earth, it has been very much warmer than it is now.

For the last four million years, it has, on average, been very much colder than it is now.

A thousand years ago, there was a "medieval warm period" during which global temperatures were significantly warmer than today; to the extent that wine grapes were grown in Southern Scotland.

Five hundred years ago temperatures were significantly colder than today; "the little ice age". Opinions vary as to when the LIA ended; some say aruond 1900, others say it hasn't totally ended yet.

Note that both the MWP and the LIA occurred before the industrial revolution; they were not caused by man.

There is no "normal" temperature.

The current climate has not existed very long, and will not stay the same for very long (and this would be true even if there were no humans).

Re:Aren't we still in an Ice Age?

[protolith]

"There has never been a greater amount of CO2 in the enviroment than right at this point of time."

This is complete bullshit! The current CO2 concentrations in the atmosphere are on the order of 12%. Global climate predictive models (calibrated with painfully short term datasets) deal with CO2 or "double CO2" concentrations. An examination of geologic evidence indicates that CO2 concentrations have been historically as high as 60% during the Cambrian (ended 540 mya) and CO2 concentrations were this high until the carboniferous (Mississippian and Pennsylvanian) when land plants began to cover the globe.

"This outpouring of uncontrolled CO2 started with the industrial revolution and hasn't slowed since."

An enormous amount of CO2 was sequestered in the Proterozoic and Paleozoic in the form of marine deposited carbonate rocks (limestone CaCO3) and most of the worlds coal was deposited in the Mississippian and Pennsylvanian. The burning of fossil fuels is only circumvention of the carbon cycle, where these carbon sinks would otherwise be subducted and released through volcanic activity this process of recycling has been going on for millions of years. The sum total of ALL INDUSTRIAL ACTIVITY is akin to a few more active volcanoes on the world.
The CO2 emissions according to this site http://www.ucsusa.org/global_environment/global_wa rming/page.cfm?pageID=965 For the last 245 years for the top 20 industrialized countries are roughly half of the CO2 emissions of the 12 most currently active volcanoes
9581925304 M tons in 245 years - volcanoes 4960020000-M tons in 245 years -Industrial Countries
http://www.ees.nmt.edu/Geop/mevo/geochem/co2.html

As it can be seen Baseline volcanic activity exceeds Industrial activity this is without consideration of all of the large volcanic eruptions in the last 245 years.
According to geologic record in reference to glaciation and ice ages, before the most recent 3.5 million years of ICE ages the earths average temperature was estimated to be warmer than it is now (Based on fossil locations that point to climatic conditions for given locations) there were also interglacial periods where the average temperature of the earth was warmer than it is now. There is every bit of geologic indication that the earth should be warming as it is. Even fluctuations in solar intensity (released from the sun) coincide with warming and cooling periods.

The real problem is that in the case of climate research there is far less funding for the people that are pointing out that ITS ALL PART OF THE RIDE, than the people that want to scream that we are all going to die!

No it's not.

[Hittite Creosote]

All human activity since the industrial revolution is less than one small to moderate eruption

Uh... do you actually have a cite for that?

Because, for example, the eruption of Mount St Helens put 1 Million tonnes of sulfur aerosols into the stratosphere - these are the things that have the most effect on the worldwide climate, the ash from volcanos is local effect only.

Now, a million tonnes sounds absolutely huge. But it is still only just over five times what, say, the State of Louisiana emits as sulfur dioxide every year.

So in other words - the US easily produces as much sulfur dioxide, and more, every year than the explosion of Mount St Helens.

Or put it this way - you get sulfur dioxide from burning fossil fuels. We mine, worldwide, billions of tonnes of coal every year (the US alone produces just under a billion). How much sulfur dioxide do you think all that lot produces? The answer is that a typical small coal-fired power station (100 MW) may produce from 20 000 up to 30 000 tons of sulphur dioxide a year. In other words, Mt St Helens is worth a measly 40 small coal-fired power stations. How many of them are there in the US alone?

Re:No it's not.

[clifgriffin]

Mt. St Helens was a relatively small eruption.

I believe the poster you were responding to was citing the eruption of Mt. Pinatubo. This particular eruption in 1991 was at least 10 times as violent as Mt St. Helens.

It created an "aerosol cloud" that spanned the continents and even affected global weather.

Scientists estimated a 4 to 6 percent loss in ozone at the time. It was also said that the toxic output of this blast contained nearly a thousand times the ozone depleting chemicals that humans have created since the Industrial Revolution.

And here's the kicker: This was only the 2nd largest eruption of the 20th century!

Sometimes I think it is human pride that makes us want to be the most influential, and thus devestating, force on this planet.

Re:An ice age depending on melting ice?

[back_pages]

The History Channel or The Discovery Channel has a very revealing documentary on this topic exactly. It hardly even touches the topic of global warming. It carefully explains the deep ocean currents that run from the Atlantic NE around Africa to the Indian Ocean and around Australia to the S Pacific, and how this current circulates the Earth's water supply and regulates climates. It goes on to point out that these deep ocean currents travel at something like six inches per hour, and a water sample pulled from the bottom of the S Pacific can be dated to roughly 2000 years ago (based on atmospheric conditions and contaminants in the water.)

This is a pretty strong argument that the higher lattitudes are temperate because of the regulating effects of the currents. Siberia is a frozen waste because it benefits from no nearby warm current, and the Sahara bakes while the Amazon is merely tropical because of the proximity to a regulating surface current. If the deep ocean current were disrupted, there is reasonable and significant doubt that a different suitable global ocean current system would develop to prevent the low lattitudes from turning into a planet-wide desert while the high lattitudes make Siberia look like a warm vacation spot.

Then it demonstrates in a fish tank how cold water currents cannot descend in fresh water as well as in salt water. This is exactly what happens near Iceland, where the warm Atlantic surface current hits Arctic waters and drops to the ocean floor to fuel the deep ocean current. Already they have scientific measurements to suggest that the deep ocean current is being fueled less now than it was 30 years ago, before which nobody understood the importance of salinity in the oceans and the deep ocean currents. This correlates to the alarming increase in icebergs which have broken away from the polar ice caps over the last few decades (something like a 500% increase, by the way.)

And the documentary takes only 60 minutes, including commercials.

Re:Wait... so you're telling me...

[Dirtside]

More accurately, the books the movie is based on were written by Bell and Strieber. They didn't write the screenplay (or at least they're not credited with it; Roland Emmerich and Jeffrey Nachmanoff are).

A brief Synopsis - How Global Warming = Ice Age

[RevMike]

The Gulf of Mexico is a large tropical sea with very warm water. A major ocean current, called the Gulf Stream, carries warm water from the Gulf up the east coast of the United States, starts to curve to the east as it passes Virginia, makes a sharper turn east near Cape Cod, heads straight for Ireland and Britain, turns south and heads down the French coast to Spain. The heat from the Gulf Stream warms northwestern Europe, and is the reason why London is as far north as Quebec and Moscow, but doesn't get 4 meters of snow every winter.

The mechanism that causes the Gulf Stream to flow is that cold water is denser than warm water. The arctic water up near Greenland and Iceland sinks and the warmer, less dense water from the Gulf of Mexico flows up to take its place.

However, salinity also affects water density. If enough fresh water from the ice cap melts and flows into the area around Newfoundland-Greenland-Iceland-Scotland, the water won't be dense enough to sink. Therefore the warm water will stop flowing north from the Gulf of Mexico.

Now London gets 4 meters of snow. Scandanavians laugh at them.

Of course, this will also cause the ice cap to stop melting in this area, but it will take quite a long time to "prime the pump", perhaps several thousand years. In the meantime, the northeastern United States and Northwestern Europe experience an "Ice Age" where their climate more closely resembles the climate of Russia at similar lattitudes.

Re:The Cassandra effect and Public discourse (long

[uncadonna]

Is it even legitimate from a mathematical-modeling viewpoint to talk about long-term average behavior?

Indeed, in a formal sense it is not easy to make a distinction between climate and weather. The casual statement "climate is the statistics of weather" becomes formally unsatisfactory when one starts to talk about climate change .

Nevertheless, I hope you will admit that I am saying something both meaningful and true when I say that the climate of Kansas City Missouri is more variable than that of Portland Oregon. How to cast this into a formal mathematical statement is not obvious, but probably not relevant for the current discussion. Whether it ought to be a practical issue for the field is something I've wondered about, but I don't think it's a current topic.

Interestingly, "climate" is conceptually better defined in our complex models than in the real world, because our models have finite sets of forcings and of free variables, and thus a clearer distinction between intrinsic and extrinsic variability than the real world does.

The prediction you make about 2304 is reasonable, but hardly long-term by geological standards.

Actually, the prediction is robust for any location at 40 degrees north latitude, at any date, on physical grounds, as long as the atmosphere is not almost totally opaque to incoming shortwave radiation (a.k.a. "sunshine") as on Venus.

I simply use it to illustrate that the predictability horizon of weather (defined as preturbations about the climatological mean) does not amount to a predictability constraint on the climate itself. I will make the same assertion for 30,000 years in the future, if you assure me that "Chicago" will be meaningful that far into the future (which I very much hope will be the case!)

I understand this doesn't go directly to your question, which is mathematical rather than physical. Climate is definitely not stationary, and quite possibly not even ergodic.

Climate is easy to define formally in our models though, much more so than in the real world. Our models can do multiple realizations of a particular year, based on specific boundary conditions and forcings. We capture enough of the variability in these models that the realizations differ. We treat the variations among these realizations as stochastic weather and the commonalities as deterministic climate.

In the real world, as opposed to in models, there is only one realization, and in fact, no clear distinction between intrinsic and extrinsic processes. So our meta-model, our model of the model, is difficult to justify formally.

In practice we don't dwell on this much. We just treat the real world as a superposition of chaotic dynamic variability (an unpredictable part) and deterministic climate change which sets up the statistical properties of the chaos.

In the simple chaotic dynamics view, weather is the state of the system (the wandering dot), and climate is the shape of the set of permissible trajectories (the whole phase diagram). Things aren't necessarily that simple in fact, but we don't have a better way of addressing the issue. Ultimately, we aren't trying to prove theorems, we're trying to elucidate complex physics, and this view appears to be both necessary and sufficient for most of our purposes.

Re:Nuclear

[WalksOnDirt]

Not 18,185,947,580,800 kWh. From your own numbers it should be 18,185,947,580,800,000 kWh available from solar (you were off by a factor of 1000).

Completely moving to solar electric would be very expensive with current technology, and use a lot of land, but it probably could be done.