Should we be more worried about atmosphere density than CO2?

Question

In a debate about global warming as it relates to the planet mars it was pointed out that the majority of Mars atmosphere is mostly CO2. But then another user pointed out that it had relatively little atmosphere. If you want to see what happens to a planet that has too much atmosphere comprised mostly of green house gases just look at Venus which is an inferno.

In light of all this wouldn't make sense to measure Earth atmosphere density not simply the amount or ratio of CO2?

Answer 1

I am not aware of anything changing the density -- it is the composition of the atmosphere that has changed dramatically in the last 200 years (since industrialization).  It is not just CO2 but also Methane, Nitrous Oxide, halocarbons and Ozone.

Answer 2

If something man-made or natural were changing the density of our atmosphere, that would probably be a concern.  But the density of our atmosphere (relatively speaking) is extremely stable compared to the amount of CO2 (which has increased by 30% in a short time).  So I'd answer "no", we don't need to worry about our atmosphere density. It's the 30% CO2 rise, and climbing, that concerns us.

Answer 3

I think a measure of atmospheric density  barometric pressure (the weight of the atmosphere pushing on you).  I think to really have a significant effect of atmospheric density,  you would need to change the size of the planet and the components of the atmosphere radically (not just a  billions of tons of greenhouse gases per year, but really radical).   I don't think that this is nearly as likely to happen as global climate change due to burning fossil fuels, landscape changes, etc.    Any event that could cause a sudden change in atmospheric density would not be good and would make AGW a very minor issue for the microbes and insects that might survive such a change.

Answer 4

I'm more concerned about unicorn farts than CO2....so, yeah.  Sure, why not?  Call me when science discovers that giant ball of burning gas in the sky...

Answer 5

Sure. I'll bet there is  dissertation in it somewhere too, and grant money for the research. Are you changing fields?

Answer 6

It does not make sense to find out atmosphere density, partially because C02 is the largest increasing proportion, but also because if our atmosphere was only 5 meters high, it would be very dense, but only as hot as if the atmosphere was spread out over 50 miles, as the same amount of heat is still trapped, density plays little part with the gases that effect us, but that may not apply to other planets.

Answer 7

I think what makes the most sense if for skeptics to learn about atmospheric physics and chemistry.  Then, perhaps, they would be able to understand why the current theories of atmospheric radiative transfer correctly model mean temperatures on Venus, Mars, and Earth.  And they would also understand why that same theory indicates there is at least a teensy weensy bit of evidence that the amount of CO2 in Earth's atmosphere is indeed important.  

Or you could go on as you are, asking questions like this.  Your call.

Answer 8

Well that's a valid point - if you're looking at other planets, you need to consider both the percentage of CO2 and total amount of atmosphere in order to determine how much of a greenhouse effect there is.

The Earth's atmosphere is so well measured that we don't really need to worry about that.  We know the atmospheric CO2 level hasn't gone above 280 ppm for millions of years (until recently), and we know how much of a radiative forcing that causes (about 1.6 W/m^2).

Answer 9

One of the Best Questions on this site with Few of the Best Answers... This site is becoming productive now.

Cheers!!

Answer 10

I don't think there is much reason for concern. 450 million years ago when the atmospheric composition had CO2 at over 4000ppm, the Earth was stuck in a major ice age for over 20 million years.

Since man has been monitoring atmospheric CO2 and temperature with any accuracy, only about 150 years, CO2 has increased by about 38% and the global average temperature has only increased by .6ºC

We are only just beginning to understand the complexities of our climate.

Answer 11

That is a good strong point there. The atmosphere density can probably effect the global temperatures if we talk, think  and research on it more.

You should tell the scientists that we should be more worried about atmosphere density. Who knows? Your name will probably appear on the news!

Answer 12

We need to worry about how much total CO2 is in the atmosphere.  It's typically measured in parts per million, which is a volume ratio and not a mass fraction.  Another way to give it would be to give the partial pressure of CO2, that essentially would be taking the atmospheric density into account.  But so far the average atmospheric pressure is not changing significantly (it averages about 1013 mb) and so partial pressure is directly proportional to the volume fraction and it works just fine to give the volume fraction.  If mean sea level pressure started changing significantly we'd have to be more careful.

If we move our calculations to another planet (like Mars) we'd have to take into account the difference in total pressure if we want to make a comparison with Earth.

Answer 13

None of those planets have plants to recycle the air.