If carbon dioxide makes up only a minute portion of the atmosphere, how can global warming be traced to it?

Question

And how can such a tiny amount of change produce such large effects?

Answer 1

It is precisely BECAUSE it is such a small portion of the atmosphere. If you increase something big by just a little bit, then you'll never notice a difference. If you increase something small by that same amount, then you notice a huge difference.

Learn more about how carbon dioxide's interaction with sunlight affects the planet's environment below:

Answer 2

The only molecules that contribute significantly to global warming are molecules with a dipolar moment ie. molecules that are not "symmetric". That means the most numerous gases in the atmosphere, oxygen, nitrogen, argon and other noble gases have no effect. Take these out of the mix and carbon dioxide makes up a significant amount of the remaining gases. Of the remaining gases, water vapour(!) is the gas that contributes the most, but the amount of water vapour in the atmosphere is indirectly controlled by the other greenhouse houses, of which carbon dioxide is the most significant. The reason such a tiny amount makes a change is because increased carbon dioxide increases temperature such that water vapour increases too, amplifying the effect.

Answer 3

In short, it can’t – at least not with any great degree of certainty.

Most people think that, since CO2 is a greenhouse gas and since the amount of CO2 in the atmosphere has risen, the temperature of the atmosphere must also have risen..

This is a fair enough assumption, but that’s about as far as you can go, because the scientific understanding of how CO2 levels will effect temperature is not well understood.

In fact, the scientific understanding is so crude that the central question…

“By how much can the temperature be expected to rise as a result of a given additional amount of greenhouse gas in the atmosphere?”

…has not been definitively established either empirically or theoretically. It has been established by laboratory experiment that increased CO2 concentrations can cause additional scattering of outgoing longwave radiation at the tropopause, but not at or near the surface, and only at the fringes of one of the three principal absorption bands of CO2. It has been established that the stratosphere is cooling, suggesting that less outgoing radiation is emerging from the tropopause. But it is insufficiently clear whether or to what extent the temperature increase since 1900 is attributable to anthropogenic as opposed to natural factors, and it is not even clear by how much the temperature rose between 1900 and 1998 (NCDC US global mean temperature anomaly 0.3°C, AccuWeather from land-based stations 0.45°C, NCDC global mean 0.53°C; UN 0.6°C). (http://ff.org/centers/csspp/pdf/20061121_gore.pdf )

So, you can see that the idea that human production of CO2 is causing global warming is not quite as clear cut as it seems.


Can I just comment on the answer from ‘Brian L’ (above)? He says…

“It is precisely BECAUSE it is such a small portion of the atmosphere. If you increase something big by just a little bit, then you'll never notice a difference. If you increase something small by that same amount, then you notice a huge difference.”

Well, it depends how you define “a little bit”. Nitrogen, for example, accounts for around 78% of the atmosphere. If we assume the “little bit” is say, a 1% increase, then that’s an increase of 7,800 parts per million.

Now, he is correct that if CO2 had risen by that amount it would indeed be a huge difference. It would mean that CO2 would have risen to nearly 30 times the level it was a century ago.

But, of course, CO2 hasn’t risen by anything like that amount. It hasn’t risen by 7,800 parts per million, it’s risen by about 100 parts per million; from around 280 to around 380 – a rise of about 36%

If nitrogen had risen by the same “little bit” it would amount to a rise of around one hundredth of one percent (0.013%). That sort of rise wouldn’t be called “a little bit”, it would be called “undetectable” or if it was detectable, it would be considered a mere irrelevant “fluctuation”.

To put it into perspective, the last century’s rise in CO2 amounts to 0.01% of the atmosphere. To put it another way, if you laid the whole atmosphere out on a one mile long road, CO2 would have increased by less than 18 inches in 100 years.

Answer 4

Carbon Dioxide isn't precisely a hint compound interior the ambience. it is not as prevalant as, say, Nitrogen or Oxygen, yet far greater so than Boron or the like. additionally, CO^2 has a fashion of starting to be a chain reaction: The greater there is interior the air, the greater CO^2 is produced. warmth is going up, greater carbon dioxide, greater warmth, greater carbon dioxide, etc. to that end, the outcomes advance exponentially quite than incrementally. a million -> 2 -> 4 -> 8 -> sixteen etc... -Daniel

Answer 5

The earth cools by radiating energy in the infrared which for the most part is blocked by water's strong absorption bands. CO2 absorbs radiation in the some of the spectral region that are left open, but because of its low concentration, substantial energy loss still occurs in those spectral region. Since there is no other way for the earth to loose heat how much radiation can escape in these regions is critical.

Answer 6

Of all the places on your body, if you have a zit on the tip of your nose, why does it hurt more and cause greater embarrassment if you squeeze it?