What if there were no humans - would CO2 be increasing?

Question

From a scientific standpoint, would the levels of CO2 in the atmosphere be increasing on an Earth with no humans (or other industrialized beings) given the same temperatures we are experiencing today?

We are bombarded with claims that current CO2 increases are man-made. Is 100% of the increase attributable to man?

Answer 1

On a planet with no humans, the following would be true, as it is true on a planet with humans.

As temperature increases, the solubility of CO2 in water decreases, thus there would be increasing CO2 in the atmosphere. Of this, there is no doubt. Gases are less soluble in water at higher temps, this is an undeniable physical property.

This is the crux of the problem with AGW. Is the CO2 increase manmade and driving temperatures up, or is it that rising temperatures (by some other cause) are causing the rise in atmospheric CO2?

Percentge attribution at this point is sketchy.

Some people lay 100% of the warming at humans feet, unrealistic in my opinion.

There are studies out there that report 50% of the 80's and 35% of the 90's warming was due to the sun, the remainder being anthropogenic in origin (ref 1).

Another paper states that .01 F of the 0.56 F rise over the course of the last century is antropogenic and that we are in a cooling geologic epoch(ref 2).

Yet another paper suggests that we are due for cooling based on its study of 20 and 60 year oscillation pattern of global temperature (ref 3).

Finally, another paper has documented that Greenland was warmer and warmed faster in the 1920 to 1930 decade than it has in the 1995 to 2005 decade (ref 4).

What we have are a variety of processes that could potentially be warming the planet, none of them are mutually exclusive of the others. At this point we do not have the tools or the models to reliable state the % attribution to any one potential source for warming.

Answer 2

Most of the current increase is attributable to man. During the time we've been on the planet levels have varied between 190 and 280 parts per million by volume - for a million or so years they've been fairly constant. In the 200 years since the Industrial Revolution they've jumped to the level they're at now - 384ppmv.

Even without humans on the planet it would have warmed and cooled over periods of a several thousand years of it's own accord, these short cycles are part of a much larger cooling cycle which has been ongoing for 50 million years ('cooling' wasn't a typo, the long term trend is actually one of cooling).

There would have been natural fluctuations in CO2 levels as well but on a much smaller scale than the current rise.

Temperature and CO2 are inexorably linked through the Feedback Cycle - increase one and the other follows, it doesn't matter which comes first.

Answer 3

With the same temperatures, but no man-made CO2, the levels theoritcally should be substaintially lower. Most, if not all CO2 is made by humans, even through our breathing. So my guess is no, it would not be increasing.

Answer 4

acctually if you look at the science the CO2 levels rise because of the heat. If the CO2 also caused the heat, the earth would never cool. because it would keep throwing more and more CO2 into the air.

Answer 5

Actually, it _has_ been proven that most of the increase is due to man.

Look at this graph.

http://scrippsco2.ucsd.edu/graphics_gallery/mauna_loa_record/mlo_record.html

The little squiggles are nature doing its' thing. CO2 falls a bit during summer when plants are active, and rises during the winter. The huge increase is us, burning fossil fuels (in addition to the shape of the graph, the increase numerically matches the increase in fossil fuel use).

The scientists can actually show that the increased CO2 in the air comes from burning fossil fuels by using "isotopic ratios" to identify that CO2.

The natural carbon cycle buried carbon in fossil fuels over a very long time, little bit by little bit. We dig them up and burn them, real fast. That's a problem.

The following graph shows the currently accepted contributions of various things to global warming. The sun is very carefully measured and amounts to about 10% of it.

http://www.globalwarmingart.com/wiki/Image:Climate_Change_Attribution.png

Answer 6

Yes. Any idea Just how big the Earth really is (or how insignificant we are)?

Pull this picture up:

http://astro.technetium.be/images/planets/earth.jpg

Now if you have an average size monitor, look at the zero on your keyboard (not the ''O''). All eight billion of us humans could fit in that ''0'' each in his or her own six foot by six foot box.

Pathetic, ain't it?

Answer 7

sure it would

the forest gets overclogged with garbage
then gets caught on fire .. then you have massive forest fire which can destroy huge number of forrest acres.