Isn’t warming from CO2 a diminishing return ?

Question

Such that each 10ppm of CO2 has less warming effect than the last 10 ppm?

Answer 1

Yes and no.  There's two factors that affect this.

The first is that, while it is a"diminishing return" the rate at which each added increment of CO2 raises the temperature declines slowly. We'd have to be up to several percent total, at least, for the decline to be noticeable--and at that point never mind, we're already dead.

The other is a feature of the thermal effects we've seen on other planets--notably Venus--a "runaway warming effect." We DON'T have good models of this as far as what might happen on Earth--or even if this could happen here. what appears to occur is a revrrse of the "diminishing returns"  temperature curve--at a certain point, the heat trapping (greenhouse) effect combines with other factors to send the temperature spiraling upward.  Beyond a certain point, of course, this effect ends and a more normal temperature curve returns--but at a far higher temperature.

The latter scenario is just for your information--there's really no way we could reach the point of triggering a runaway greenhouse effect.  The bottom line for our civilization is that by the time a diminishing return effect in the temperature curve became significant, the temperature would already have risen more than is predicted in the worst-case models.  And if that happens, a flattening of the curve will compe too late to help save us.

Answer 2

How is that possibly diminishing? 10+10 = 20. The next 10ppm doesn't mean 10/999,990. It still means parts per million. Maybe I just misunderstood your question wrong though and you were referring to a scientific theory that has nothing to do with the math I answered with >_>

Why would it have less of a warming effect? It's still 10 more molecules and has the same effect as the last 10. But I don't seem to understand it properly anyway. Last guys respone is much better than mine.

Answer 3

Yes - CO2 increases surface temperature by reflecting radiated heat back to earth.  It also blocks inbound radiation along the same wavelengths, but there is less of that coming from space than from earth.  Once the energy is reflected back additional CO2 won't reflect the same energy.  

That much said, the climate is a dynamic system, so there could be thresholds that trigger other changes.

However, despite the pompous proclamations of self anointed experts, we don't begin to understand all the factors that drive climate.  The science isn't all in, we don't know all the answers.

Answer 4

Most of the CO2 problem is taken care of by the need of the green plants.  

Answer 5

As CO2 increases, so will plant life as they need it to survive and in return we'll be supplied with more oxygen.

Increased plant life have many benefits that outweighs any cons of CO2.

Answer 6

Eventually, yes, that's why the Earth in the past did not have runaway heating.

We're nowhere near the point that happens.  Right now the effect of the next 10ppm is very nearly the effect of the last 10 ppm.

The reason it's eventually a diminishing return is not really the CO2.  It's the fact that, as temperature goes up, the fraction of heat that's radiated upwards goes up faster.

By the time that's effective, we WOULD be under several feet of sea level rise.

Answer 7

The effect of CO2 is saturated as CO2 only absorbes three narrow bands of radiation, only one of these is significant and this band is already saturated with only minor spectural broadening occuring with increased CO2.

According to the IPCC, the 100 or so ppm of the last 100 years has caused at least 0.2 degrees of warming.  Using their own numbers, the next 100 ppm would cause closer to 0.1 degrees of warming.  A lot of more objective scientists (including a number of climatologists) think the IPCC's 0.2 estimate has no scientific basis and the climate is much less sensitive than that.  

Answer 8

Although 'diminishing return' isn't exactly the right term to use the answer is yes, each 1ppm does produce less warming than the previous. Eventually, there could be enough CO2 to trap all the suns energy at the wavelengths that CO2 traps. Then the temperature of the planet will rise until an equilibirum is reached with radiative effects back to space.

BUT, as bob points out, we're a long, long way from that, in terms of time, temperature and CO2 concentrations.

P.S. to both antarctica and Randall. The celsius scale is arbitrary and cannot be used for the comparisions that you do. To say that 2 degrees is twice as hot as 1 degree implies that the energy content has doubled which is quite false. If you wish to compare temperatures in percentages or quantum levels, you need to use the Kelvin scale wherein Earth is 288 degrees and Venus is 734 degrees thus Venus is approximately 3X as hot as the Earth.

Answer 9

do a little more research and repose the question more precisely

bioaccumulation has slowed, however, free-cycling radicals remain, present output of CO2 are far less than 10 years ago....

but, as you have seen the math: 10+10=20.....so how would you prefer to view this matter?

we are ready to consider this issue in a more specific sense

Answer 10

Yes, it is because CO2 only reacts with IR energy in three narrow bands, those bands are saturated, you can run the simulations with the following widget.

http://geosci.uchicago.edu/~archer/cgimo...

Answer 11

Yes, the warming from CO2 is logarithmic and not linear as many would have you believe.  Based on the Beer-Lambert law, it will take twice as much CO2 to produce the same amount of warming that the previous amount of CO2 caused.

Example: If 100 ppm CO2 emissions causes .5 C warming, it will take 200 ppm to cause the next .5 C warming, 400 ppm the next and so on.    

Answer 12

That is correct.  See:

http://brneurosci.org/co2.html

Here is another statement from the Britannica Encyclopedia online:

"Radiative forcing caused by carbon dioxide varies in an approximately logarithmic fashion with the concentration of that gas in the atmosphere. The logarithmic relationship occurs as the result of a saturation effect wherein it becomes increasingly difficult, as CO2 concentrations increase, for additional CO2 molecules to further influence the “infrared window”..."

Nobody on either side of the AGW issue disputes this.

Answer 13

Diminishing returns are minor, in the last 100 years co2 has risen over 100ppm and the temp has risen 1deg over the next 100 years co2 is set to rise at least another 200ppm with the temp set to rise by about the same proportional amount 2 deg so little diminishing effect seems likely in the medium term.

Randall E: Earths temp is 15c, Venuses temp is 461c

Venus is 30 x Earths temp not 15

Answer 14

Yes - it's an insulator, not a heat source.

If you put a layer of insulation on a house that doesn't have it, it will have a significant effect.   A second will have a noticeable effect but not the same effect.    The difference between the sixth and seventh layer, if you could fit them, would not be noticeable.

Past warming periods that were CO2-driven involved temperatures about 30%-40% higher than today - and CO2 levels 12-15 times higher.    Not 27% higher, 1,200% higher.

Venus' is about 15 times hotter than the Earth.   Venus' atmospheric CO2 concentration is thousands of times ours.

So yes, there are diminishing returns.

Rapidly diminishing returns.