But don't worry CO2 has very little to do with warming our climate, it works well in climate models, but the models are static, not like our atmosphere which dynamic, heat is transported from the surface to the troposphere by convection, evaporation, and condensation, not by irradiation.
Good question Ben.
Humans emit a cocktail of greenhouse gases some of which remain in the atmosphere for a comparatively short time, other a long time.
Methane for example has an Atmospheric Residence Period (ARP) of 12 years whereas some of the chloro/halo-fluorocarbons have an indefinite lifespan. Carbon dioxide, the greenhouse gas we produce the most of, has a variable ARP of about 115 years, methane is our second biggest contributor to global warming with nitrous oxide coming third, this has an ARP of 114 years. The only other gas we produce in significant quantities is dichlorodifluoromethane with its ARP of 8,500 years. All the other gases, of which there are thousands, make up less than 0.5% of man’s contribution to global warming.
In answering your question we also have to take into account the different Global Warming Potentials (or GWPs) of the greenhouse gases. This is a measure of how effective the different gases are at causing warming.
Carbon dioxide provides us with the baseline figure of 1.000 against which all other gases are compared. Methane for example has a 100 year GWP of 25, meaning that across a 100 year time horizon a unit of methane will cause 25 times more warming than the same quantity of CO2. Nitrous oxide is 298 years and dichlorodifluoromethane has a GWP of 8,100. The other greenhouse gases vary up to a maximum of 22,800 years for sulphur hexaflouride.
The actual calculation itself is simple, if somewhat longwinded. Fortunately it’s something I had to calculate for a consultation paper so I can tell you that the answer is approximately 84 years.
To clarify, that means that if, with immediate effect, we reduced our emissions of greenhouse gases to nil it would take about 84 years for the requisite proportion of our historic emissions to dissipate out of the atmosphere such that no further warming would occur and a state of quasi-equilibrium would be reached.
There are of course factors over which we have no control such as the natural emissions and sequestration of greenhouse gases, as such the figure of 84 years is a variable one. However, if nature were to be suspended, so to speak, and have no bearing on the outcome, then 84 years ±3 years would hold.
This point in time is when no further warming occurs, not when temperatures return to ‘normal’. However, the temperature trend would now be a decelerating downward one tending close to zero at the point when only the indefinite ARP gases remained.
I haven’t done the calculations but expect it would take a further 30 to 50 years before the temperature fell to a point where we could consider it to be on a par with that which existed prior to any manmade warming.
The extra greenhouse gases we have generated since the beginning of the industrial revolution are already enough for AGW to go beyond 2100. If CO2 were continually reduced that would reduce the effects and maybe shorten the time period If we do not start making changes, it could go beyond 2200
5 years is the life of emitted CO2 in the atmosphere.
http://wattsupwiththat.com/2011/02/16/th...
But considering that recent global warming is causing us to freeze to death stopping CO2 emissions might just cause the earth to turn into a fire ball from hell unless we tax people more, destroy capitalism, and create a totalitarian world government full of unelected and unaccountable politicians.
According to the denier morons on the right, it never would happen.... it's apparently "all natural" to have such a high CO2 content.
Billions of years, jk, but I am sure a liberal will answer it this way.
