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Name: Austin
Status: other
Grade:
Location: CA
Date: July 2008

Question:
Do CO2 and other greenhouse gases disappear over time? I have read that if we totally stopped emitting CO2 today, it would take hundreds of years to get the CO2 level in the atmosphere back to pre-industrial levels. But that does not really answer my question. I want a straightforward answer: Do CO2 and other greenhouse gases disappear over time? Thank you for your assistance. Just trying to get this figured out.



Replies:
Carbon Dioxide in the atmosphere is part of a cycle just like nitrogen, oxygen or rocks. It is removed from the atmosphere by marine organisms that use it to create shells and then sink to the bottom of the ocean and eventually become rock (limestone). Plants that use it and are buried (peat) also remove it from the air in a semi-permanent way.

Actually, the amount of carbon dioxide in the air and, the world average temperature are lower than they have been in the geological past. The main problem is how fast temperatures are rising. They are rising too fast for plants and animals to adapt to the change. That and we are here with our agriculture, livestock raising and other environmental modifications which we desperately want to protect.

Robert Avakian


Austin,

The answer to your question can be found in tracing how CO2 flows through the environment. Use Google pictures to look up the "Carbon Cycle." The carbon cycle shows how CO2 moves and gets stored in the environment.

Warren Young


Austin,

CO2 is one of the main components in photosynthesis. So, assuming that there are enough plants, and whatever activities that produce CO2 do not produce more than what photosynthetic plants consume, then CO2 levels will go down.

Greg (Roberto Gregorius)


CO2 and greenhouse gases do not 'disappear', but they do participate in complex global processes where they are chemically converted, absorbed, or released by or in the ground, air, and oceans. CO2 might be absorbed into the ocean or chemically incorporated into rock, for example. There are many, many different processes at work, and it is a very hot topic of research to figure out exactly where and how much of each gas is going -- we are far from having a complete and accurate understanding of all the phenomena.

Hope this helps,

Burr Zimmerman


I know you have asked for a straightforward answer, but I am afraid a SIMPLE straightforward answer is not possible.

You may remember in science in early Middle School being told about the Water Cycle. Water is evaporated from the sea to become clouds which rain on the land, move into river which run to the sea, and so on and so on...

Carbon has a similar cycle, but it moves so much more slowly than the water cycle that it is easy to not see it.

Carbon exists in the air as carbon dioxide. CO2 is absorbed by plants, where the carbon is locked up as carbohydrates, cellulose and lignin. (All ingredients of wood!!) Some plants are microscopic, such as plankton in the sea, many are conveniently meal sized and are eaten. As the animal digests the plant it breathes out carbon dioxide, returning the carbon to the atmosphere. When a tree dies it decomposes, and the carbon is returned to the atmosphere as carbon dioxide expelled by bacteria and other microorganisms. In some cases the carbon remains locked up as peat or oil or coal.

Since the industrial revolution we humans have been using wood and coal as fuel to drive our machines. We have also burned down huge areas of forest to make room for farming. Burning the wood or the coal returns the carbon dioxide to the atmosphere thousands of times faster than it would be locked up by further plant growth.

If we were to suddenly stop burning all coal, oil and wood, the carbon dioxide in the atmosphere would slowly be reabsorbed by plants and turned back into more wood. We humans on the other hand would be in DEEP DEEP trouble. Our lives depend too much on vehicles running on oil, and machines driven by electricity which mostly comes from burning oil or coal.

Many of the other gases which are deemed to contribute to the greenhouse effect, such as methane and fluorocarbons, occur in much lower concentrations than CO2, and would slowly be absorbed into soils and water, or would be changed by the action of sunlight and chemical breakdown. They too would eventually disappear, but much more slowly, as there is no ongoing process which would consume those chemicals.

I apologize that this is not a straightforward answer, but as I said, such an answer is not accurate.

If you insist on a simple answer, then YES - they do disappear, but only in the way that apple pie disappears - by being turned into other substances. Hopefully, in the atmosphere, the new chemicals will be less harmful than the chemicals we started with.

Nigel Skelton
Tennant Creek
AUSTRALIA



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