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?

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!

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

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.

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!

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.

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.

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?

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.

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.

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

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

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.