Global Cooling

[airdrik]

They say that too many greenhouse gasses in the atmoswhere causes global warming. How do we know that the opposite isn't true?

The way the greenhouse effect works is that heat from the earth bounces off clouds and things in the atmosphere and comes back to earth, but some of the heat still escapes. Heat from the sun also gets absorbed by, and bounces off of clouds and things in the earth's atmosphere as well.

The question is: How does the amount of heat that enters the earth's atmosphere compair to the amount of heat that leaves?

It is just as likely that global cooling will occor than global warming.

[EnochF]

Wait... are we talking about Civ or not?

One recent report I found documents the melting of ice in Antarctica and the North Pole. Who knows if it's caused by human pollution... I'd have to take a look at the source code for the Planet Earth. Can anybody burn me a copy?

[Lung]

Err, interesting comment, but what does this have to do with Civ3? Perhaps they could throw in a low percentage of probability that an ice age envelops the earth instead of globel warming, but i think that you're clutching at straws

[Lancer]

Actually he's right. I read a post by someone recently, (they should take credit if they see this) that global cooling would result frome a nuke war, not global warming as is represented in the game. When I read his post one word came to mind...DOH! airdrik is dead on, nuclear winter is what he's talking about...

[airdrik]

Yah, maybe in civ 3 industrial pollution causes global warming and nuclear pollution causes nuclear winters, but one doesn't counter the other, so if you have tones of both types of pollution then you will get a mix and some tiles change into warmer climates and others (even those next to those that changed to warmer climats) change into colder climats. If you keep it up and continue using nukes, and don't do anything about the industrial pollution, then the planet becomes uninhabitable and you loose the game .

Of course, this is only after using no less than 75 nukes and spending no less than 1,000 pollution-turns (after (1,000/ the number of tiles of pollution) turns). You can recover pollution-turns mearly by cleaning up pollution: pollution being cleaned up does not count towards this number, and after you clean the square it decreases your total by a certain amount.

[Stuff2]

Actually global cooling is depending on one thing. How much crap in the athmosphere that blocks the sunshine. A nuclear war would make tha atmosphere full of dust and therefore cool down the climate. But sooner or later dust falls back to the earth and the global cooling effect ends. The same thing happens when there are giant volcano eruptions or even a 'normal' modern war (even if the effect is so slight that it's hard to measure). I've read somewhere that 1995 was in general 0,5 degrees colder on the whole earth beacouse of the pinatubo eruption (i think the name on the volcano was something like that).

Although reality is extremely complex, i think a civ-game should stay on a simpler level.

[Nikolai]

Actually global "warming" would warm some areas on the Earth, and cool other parts of it!

As an example, take Norway. At the coast of this country, the Golf stream "flows". This stream is warm water from the mexican gulf, and without this water Norway would have been ice, ice, ice, and nothing other than ice!

And, if the global warming the scientists are talking about, will come, and the same scientists are right, the Gulf stream will either disappear, or change direction!

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Who am I? What am I? Do we need Civ? Yes!!
birteaw@online.no

[airdrik]

That's the kind of things I wanted to bring up here, is that 'destruction of the environment' doesn't have to lead to global warming, but the general degredation of the earth. Pollution might cause global warming, but it could also cause some places (like Norway) to get cooler. And if nuclear weapons are used excessivly then you will get a nuclear winter and everything will cool down a notch.

[Dauphin]

With nukes its just a matter of how much dust is thrown into the air - asteroid impacts caused mass extinctions because collisions threw tonnes of rocks half way to the moon before they fell back to Earth (I'm not exaggerating). Only ground impact nukes would cause this type of effect.

quote: The way the greenhouse effect works is that heat from the earth bounces off clouds and things in the atmosphere and comes back to earth, but some of the heat still escapes. Heat from the sun also gets absorbed by, and bounces off of clouds and things in the earth's atmosphere as well.

Clouds have a net effect of cooling the earth. Carbon dioxide does nothing but keep us warm. Without greenhouse gases the planet would have an average temperature of -20C or so.

Hope you've learnt todays lesson.

Overall natural unpredictable climate change would be more suited to the game. Things like the mini-ice age in the European middle ages

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Never argue with a fool; People might not know the difference

[Stuff2]

quote: Originally posted by Nikolai on 02-02-2001 03:11 PM Actually global "warming" would warm some areas on the Earth, and cool other parts of it! As an example, take Norway. At the coast of this country, the Golf stream "flows". This stream is warm water from the mexican gulf, and without this water Norway would have been ice, ice, ice, and nothing other than ice! And, if the global warming the scientists are talking about, will come, and the same scientists are right, the Gulf stream will either disappear, or change direction!

That sound scary. I live in Sweden next to Norway and it's cold as it is right now (I think it's around 5 degrees farhenhiet). We certianly don't need the weather to become colder in this country.

Global warming and pollution effects are greatly exaggerated in Civ2. Pollution makes things unpleasant for in tiny localities but doesn't decrease the productivity of thousands of square miles in a whole tile.

The worst case yet is Chernobyl, which only irradiated a hundred square miles or so. To the people who lived there it was catastrophic, but it didn't impact the productivity of farming in the Ukraine.

A few shellfish bedding areas of the Mediterranean Sea were heavily polluted and could not be used for human consumption. Loss of silicates and cold water flowing into the Med due to the damming of every major river has been more devastating to the overall marine ecology than chemical pollution. The influx of warm sea water through the Suez has amplified the effect.

Global warming may actually increase snowfall in the polar regions. Ice may melt in marginal areas but the icecaps could accumulate mass overall.

[Stuff2]

People often seem to think that it's the icecaps melting that will couse the ocean to rise. This is not entirely true. In fact. If Arctis melted down it wouldnt to any difference at all since the ice floats in the water already. The main reason why a warmer climate will make the ocean rise is that water expands when it gets warmer. This means that, even though a global warming will increase the polar ice, the ocean will still nevertheless rise.
It's simple physics.

[Roman]

Stuff2 is partially right. One of the reasons sea level is expected to rise is due to the fact that warmer water takes up greater volume.
There is some possibility of the Arctic getting colder, primarily due to the gulf stream being diverted. This would indeed result in the accumulation of Arctic ice, but as Stuff2 said, that would make no difference whatsoever to the sea level, since the ice is already floating.
Anyway all the evidence seems to suggest that Antarktic ice is not accumulating but schrinking, as the Antarktic is getting warmer. This is a problem because unlike in the Arctic, ice in the Antarktic is on land and hence if it melted even partially, there would be a massive rise in sea level. Actually that is not the biggest worry. The ice does need to melt to cause a rise in sea-level. It is enough for it to slide into the sea and thus displace some water. Due to global warming this seems to be starting to happen in Antarktica.

[Grumbold]

It is certainly true that a more accurate global disaster system would treat types of industrial pollution and nuclear pollution differently. Prior to 1960 the vast majority of pollution was caused by coal burning (in homes, power plants, factories) which had bad effects on local atmospheric conditions (killer fogs in London, the worst in 1955) and was harmful to the local environment. This did absolutely nothing to degrade the ozone layer and the particles in the air will have had a modest cooling effect if anything. Increasing use of petrochemicals and other complex chemical wastes has radically shifted the type of pollution damage in the last half century, leading to land contaminated for long periods and potential warming.

Nuclear accidents and exchanges are going to result in a third type: near permanent pollution of localised areas, health problems worldwide from increased radioactivity (most in the fallout path) and atmospheric dust cooling the climate. If enough dust got into the atmosphere it could trigger an ice age which would continue even if the dust subsided (more heat reflected back into space because of a greater serface albedo from ice and snow.) It would take a big nuclear exchange but I would consider the latter to be a good end-game option: you have made the world practically uninhabitable for centuries to come - everyone loses!

The current Civ model of everything leads to easily cleanable pollution is too simple IMO. The CtP variant that all pollution burns squares to ash, destroying improvements is equally silly. Lets hope Sid finds a better way.

[DrFell]

Apparently FreeCiv seperates 'normal' and nuclear pollution, normal pollution causing global warming and nuclear pollution causing nuclear winter... you might want to have a look at it.

[Dauphin]

quote: Stuff2 is partially right. One of the reasons sea level is expected to rise is due to the fact that warmer water takes up greater volume.

Depends on the average temperature. Water is at its densist at about 5C. If the average temperature is less than this then warming will decrease volume.

quote: normal pollution causing global warming and nuclear pollution causing nuclear winter...

Ozone depleting pollution is a third addition that should be made.

1. Nuclear - Nuclear winter - Global cooling
2. Greenhouse - Global warming - Raises sea level
3. CFCs etc - Causes dead tiles mainly near poles.

[Roman]

Big Crunch, average surface temperature is currently approximately 15 degrees Celsius and expected to rise by up to 5 degrees Celsius by the year 2100.
Water gets less dense when cooled below 4 degrees, because this is the point at which structure starts to appear in groups of water molecules hence destroying the tight packing of the molecules in an ordinary liquid.

[Dauphin]

quote: Big Crunch, average surface temperature is currently approximately 15 degrees Celsius and expected to rise by up to 5 degrees Celsius by the year 2100.

The surface water is only a tiny percentage of all the water. Whats the average temperature of the oceans as a whole?

[Roman]

I don't know the average temperature of all the oceans.
I can, however, assure you that it mmust be larger than 4 degrees Celsius. The reason for this is that just as you said water colder than 4 degrees is less dense than warmer water. This means such cold water would rise to the surface, but we know the surface temperature to be much higher than that.
Hence the temperature at the bottom of the ocean is at least 4 degrees Celsius and the average surface temperature 15 degrees Celsius. The temperatures in between vary within this temperature range. Obviously the average temperature of the ocean is therefore somwhere in between these two temperatures (probably closer to 4 rather than 15 degrees).
[This message has been edited by Roman (edited February 08, 2001).]

[Roman]

Nuclear war, an asteorite impact, or a volcanic eruption all have an initial cooling effect on the atmosphere, because they throw particulate matter into the atmosphere, which obscures the sun.

However, a volcanic eruption also releases a large amount of carbon dioxide into the atmosphere from the Earth's interior. Meanwhile, nuclear explosions and asteorite impacts generate intense heat at their points of impact leading to decomposition of carbon compounds and subsequent formation of carbon dioxide.

The result is that initial global cooling is followed ba a large increase in temperature due to global warming once the particulate matter settles.

[BRENNANonTHEmoor]

Good Idea to include nuclear Winter and Global Warming!

[Dauphin]

Roman, I see the logic and you are probably right that it is greater than 4C (but for other reasons.

However, by your logic the warm air at the Earths surface should rise to the top of the atmosphere - meaning its warmer near the top of Everest tahn at the bottom. Which it isn't.

The water at the surface is only warmer because heating takes place at the surface due to the sun. The amount of sunlight even a few hundred metres down is minimal. Its very cold.

Is this OT?

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Never argue with a fool; People might not know the difference

[Roman]

I see what you mean with the Mount Everest, but it doesn't quite work that way for four reasons.

1) Air at Mount Everest is much thinner and thus intercepts fewer infra-red rays from the sun than air at sea-level.

2) Air at sea level is also warmed from the Earth, which intercepts almost all infra-red radiation from the sun.

3) Higher atmosphere contains certain chemical
that act to cool it.

4) The primary greenhouse gas is carbon dioxide, which is a lot denser than air and hence tends to stay quite low in the atmosphere. It therefore traps the heat only in the lower portions of the atmosphere. Without carbon dioxide the lower sections of the atmosphere would be almost as cold as the outer atmosphere.

Of course the air rises from sea level upwards (this is what causes winds), but it has a much lower specific heat capacity than water, so it cools down relatively fast commpared to water.

[Roman]

quote: Originally posted by Big Crunch on 02-10-2001 07:17 AM The water at the surface is only warmer because heating takes place at the surface due to the sun. The amount of sunlight even a few hundred metres down is minimal. Its very cold.

Yes this is absolutely correct. However, it still doesn't stop water that is less dense than the surrounding water rising to the top, or equalising its temperature with the surroundings. In fact one of those two things must happen in the long term and both have the same effect of the least dense water being on the top and denser, 4 degree water on the bottom. It is dangerous to draw parallels with the atmosphere inn this case, due to the 4 special circumstances regarding Earth's atmosphere, I outlined above.

In fact I know this to be true with respect to lakes and seas. In all of these the temperature at the botom is 4 degrees, even in the arctic ocean. That is the reason why water freezes at the surface first and not at the bottom.

Yes, sunlight has trouble penetrating seawater due to the depth of the oceans. I agree that after say 1000 metres (this is a complete guess), the water temperature reaches 4 degrees, but after that it does not decrease any further. Precisely because I don't know where this point of thermal equilibrium is reached, I can't calculate for you the average temperature for the oceans as a whole.
It is also the reason why we can be completely certain that the average water temperature in the oceans is greater than 4 degrees Celsius.

[Roman]

Yes, this is probably OT.

[jdlessl]

One of the things that really pissed me off about SMAC was that you almost never had global cooling. You could blast an entire continent into the sky, which ordinarilly would block the sun for a couple years, but damned if sea levels didn't rise because of it.

If there are going to be weapons of mass destruction in Civ3, I certainly want to have to think about a nuclear winter.

--
Jared Lessl

[Dauphin]

quote: Of course the air rises from sea level upwards (this is what causes winds), but it has a much lower specific heat capacity than water, so it cools down relatively fast commpared to water.

Mainly due to adiabatic expansion from the reduced air pressure at higher altitudes. (I did an Atmospheric Physics module at university but not Oceanography).

quote: In fact I know this to be true with respect to lakes and seas. In all of these the temperature at the botom is 4 degrees, even in the arctic ocean. That is the reason why water freezes at the surface first and not at the bottom

I would guess that it is the higher pressures that prevents water from becoming ice at depths or under ice sheets. (Even if it is less than 0C). So I have doubts about this. I agree that if there is water at 4C it will most likely be at the bottom

I better say something on topic - The game should have global cooling in it.

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Never argue with a fool; People might not know the difference
[This message has been edited by Big Crunch (edited February 10, 2001).]

[Roman]

quote: Originally posted by Big Crunch on 02-10-2001 05:48 PM Mainly due to adiabatic expansion from the reduced air pressure at higher altitudes.

Correct indeed, I also did Physics.

quote: Originally posted by Big Crunch on 02-10-2001 05:48 PM I would guess that it is the higher pressures that prevents water from becoming ice at depths or under ice sheets. (Even if it is less than 0C).

This is not the case for two reasons.

1) The pressure of the water does not change by having an ice sheet on top any more than by having an equivalent (by weight) amount of extra water.

2) While pressure determines the boiling point of water, its effect on ice formation is only negligible.

Water in the oceans does not freeze even below 0 degrees Celsius, because it contains dissolved salts, which decrease its melting (freezing) point.

quote: Originally posted by Big Crunch on 02-10-2001 05:48 PM So I have doubts about this. I agree that if there is water at 4C it will most likely be at the bottom.

I can make this official now. This is exactly what happens, as I now looked it up. The water at the botom of the oceans is at 4 degrees Celsius.

I still have not managed to find out the total temperature of the oceans, though.


PS.
I think we have hijaked the thread by now for our intelectual discussion, but to comment on the game anyway, I would find it nice if global cooling was included, but by no means an essential feature of the game.