lizrising:

> Please explain how vegetation produces CO2. I must have missed that lesson in biology class.

Plants, just like animals, consume carbohydrate for energy and growth. A plant releases carbon dioxide as it uses carbohydrate as fuel. A plant releases and absorbs carbon dioxide and oxygen through stomata on the leaves. During the day the plant udergoes photosynthesis and converts carbon dioxide and water into carbohydrate and oxygen. This carbohydrate is used to provide energy as well as a raw material for growth. At night there is no sunlight so photosynthesis stops. Instead the plant uses the carbohydrate and releases carbon dioxide and water, the reverse of photosythesis. The plant grows because during the day it produces far more carbohydrate than it burns. Since the amount of carbohydrate is in excess of what is consumed for energy, the plant produces a much larger amount of oxygen than the amount of carbon dioxide. While a plant produces carbon dioxide, the net result is one of oxygenation of the atmosphere. Plants remove carbon dioxide and turn into glucose, which is in turn polymerized into cellulose. When you see a tree, the trunk, branches, leaves, etc. are a big store of carbon dioxide converted into cellulose. That cellulose can be burned for energy. It is why wood is a good fuel. But when we burn wood all that stored CO2 is realeased back into the atmosphere.

Does more CO2 mean more vegetation? In a greenhouse it does. Many greenhouses enrich the atmosphere with CO2 to stimulate plant growth. it works because the plants get warth, CO2, fertilizer and water. On the global scale of our atmosphere more CO2 does not translate into more vegetation when rainfall is low or the soil can't retain moisture. With global warming, rainfall will become erratic or change its patterns. The soil will retain less humidity. So more atmosphereic CO2 might mean death of vegetation rather than a lush jungle everywhere.

Übergeek 바둑이: Ah, I do vaguely remember learning that now. Thank you.

lizrising: Good questions. Plants do throw off CO2 whenever they are not producing O. They make O when there is light, but at night they actually give off CO2. Obviously I'm not talking about dropping ice cubes into an already full glass of water, that would just be like adding more liquid water to the liquid water. My point about ice and water is mostly about how water contracts when it melts. Most (if not all) other substances will expand when going from solid to liquid. You are right about land based ice melting and adding it's volumn to ocean levels, but before it can even get there other factors are in play, such as evaporation, pooling into ponds and lakes, etc etc. I think maybe the scale of the ocean makes it difficult to believe it wouldn't be a big problem.. after all, it's a big ocean, and a very deep one.

Iamon lyme: Scale really is a tricky one, but my guess is melting ice would be less of a problem for the earth than it would be for my tall glass of ice water. Less, or the same. As you can see, I care very deeply over the fate of my ice water, especially during periods of global warming..

Iamon lyme: Not as much CO2 as they absorb.. they use it to grow and lock it into their chemistry. If they didn't .... we would not be here, as plants are the reason for the decrease in CO2 levels/increase O2 that allowed animals to live on land.

Iamon lyme: you mean

"But here's one even easier to debunk. more vegetation produces more CO2."

It's called photosynthesis. Sunlight+CO2 = plant growth+O2

It's why the boffins have all looked at using plant matter as a means of long term O2 production on long space flights.

(V): Sci-fi writers talked about using algae for long space flights long before we even tried getting to the moon.. Anyway, environmental alarmists have oversimplified natural global warming and cooling cycles and make it out to be something under our control. I remember the old joke that goes "Everyone complains about the weather but nobody does anything about it." The reason we don't need to worry about dramatically overflooded coastlines is because H2O contracts (instead of expanding) when going from solid to liquid. It has to do with the crystaline structure of ice.. the molecules are farther apart when H2O becomes a solid. Also, we probably see more ice above the waterline because there is more air trapped in the ice than you would see in a perfectly clear ice cube. I hadn't thought of this one before, but if the globe was a bit warmer, then there may be increased evaporation, leading to an even higher percentage of water vapor adding to the "greenhouse effect". But the greenhouse effect is only about trapping heat after the suns rays have already penetrated the veil and reached the ground. More rays are deflected with a heavier veil, therefore over time less and less heat is produced, which perhaps helps to usher in the next global cooling cycle. I'm speculating about a lot of this, but the evironmentalists are correct when they start out telling us how complex this system really is. What impresses me is not that it goes from warm to cool, but that the extremes really aren't so extreme. They don't come close to extinguishing all life on earth.

Iamon lyme: Yes.. but ice that is locked in glaciers and the like is land based and not in the sea.. unless it breaks off or melts and then adds to the sea. Certain low island already are disappearing.

"More rays are deflected with a heavier veil, therefore over time less and less heat is produced."

Interesting, but I thought that our atmosphere extended way beyond the usual water vapour range. Or it maybe I'm just remembering the problem we had with CFC's and ozone... I thought water vapour is usually invisible.. it's in the air we breath yet we do not 'see' it. If it was sulphur.. different matter, that reflects.

"but that the extremes really aren't so extreme"... it's the % of more extreme weather that is the problem. eg our UK crops are having problems due to an extremely rare dry and hot April. Food production from this season (wheat and other cereals) will be lower.

Iamon lyme:

> They don't come close to extinguishing all life on earth.

Like I said in severfal of my posts below, the problem with global warm ing is not one of ice melting and coastlines rising. The worst that could happen is that governments will have to move cities inland as water advances slowly. Some cities already under sea level will be overrun by the sea. That is not the problem here.

The real problem is the vapour pressure of water. A change of 1 degree Celsius in atmospheric temperature causes an increase in the vapor pressure of water. That means that 1 degree rise becomes an increase of 5 to 8% in the rate of evaporation of water from the surface of the earth. Now soild are drying 5 to 8 % faster than before. That will lead to a large increase in arid regions (deserts) in the planet, and an accompanying decrease in arable land surface. That means that grain will become harder to cultivate and it will become a lot more expensive. The middle class will just pay more for their food. The real problem is the poor (which make 2/3 of the population of the world). The poor will not be able to afford higher grain prices and a lot of people will go hungry.

The problem is not one of the world "ending" as they paint it in a couple of sensationalistic movies. The problem will be one of growth of deserts and famine.

People have to get out of the "end of the world" mindset, and start thinking of a growing population and less land to feed it because deserts are getting bigger every day.

People in North America are spoiled because the Prairies produce so much grain. Imagine life with half the grain we have now, all because the planet warmed up 1 degree Celcius. The grassland prairies of North America are for the most part semi-arid. They are the breadbasket of the world and a reduction in water in the soil will push them from semi-arid to arid, making them a lot less productive. That will be the true impact of global warming. Coastlines will be merely but an incovenience when compared to famine.