How do the climate models specifically account for anthropogenic CO2 emissions?

They dont

The relationship between greenhouse gasses including CO2 and radiation trapping is well understood theoretically and experimentally verified. This relationship is accounted for in climate models. The relationship between anthropogenic CO2 emissions and atmospheric CO2 is well-documented by commercial records, oceanic and atmospheric CO2 records, and isotopic composition.

The fact that positive feedbacks, including water vapor, exist does not automatically mean that total feedback is positive. The 4th power law relating blackbody radiation to temperature is considerably more powerful that the sum total of positive feedbacks gives an upper limit and a lower limit for average temperatures for any solar orbit and the only way for the earth to approach those limits is by cutting off atmospheric water vapor supply, as has happened with "snowball earth", or by loss of all water to space

wilds_of_virginia -- <<If we are digging up sequestered carbon and putting millions of tons of additional CO2 into the atmosphere, it is reasonable to assume the temperature will go up. Are you with me so far? >> Then why did we enter a cooling period from the early 1940s to the early 1970s, while CO2 concentrations steadily rose?

You are a bit confused...

Let's go back to the basics. CO2 is a greenhouse gas, a primary driver of temperature. Doubling of the atmospheric CO2 concentration will cause an upward forcing of 1.8 C. This was established over 100 years ago by Svante Arrhenius. The models DO take this into account.

And it makes sense, too. If we are digging up sequestered carbon and putting millions of tons of additional CO2 into the atmosphere, it is reasonable to assume the temperature will go up. Are you with me so far?

The great unknown in the equation is the effect of feedbacks. If the feedbacks are positive the effect of increased CO2 will be amplified. For example, as the Arctic warms, more snow melts, leaving bare earth or open water which absorbs more light. Warmer air tends to hold more water vapor, another greenhouse gas. There are negative feedbacks as well. Models try to predict the effect of all these feedbacks to estimate the real effect on terrestrial temperature from increasing CO2 concentration. The best guess is the net effect will be somewhere between 1.5 C and 6 C.

HOGWASH on everything your saying here. All non solids like co2 that rises is separated by nature naturally & has been for billions of years. Mike

GIGO Garbage in Gospel out.

Climate models were designed only to prove Mans effect on climate, not to fully understand our climate and as such they have magnificently FAILED.

Until we Know what the ECS (climate sensitivity) is with reasonable certainty (not 1.4 to 4.5C that is just a guess) we wont be able to make predictions.

One of their biggest failings is with water vapor, they have calculated the positive feedback, but ignore water vapors enormous negative feedback, from what I see they have not even researched it, that has been left to skeptics from outside the fold.

I am sure if they wanted to, they could make the models more accurately predict the climate, but the result would not include dangerous warming, which would defeat their purpose.

You are clearly very misinformed about climate models.

<< It is assumed in each of these models that CO2 is the primary driver of the temperature, and that H2O vapor is merely the feedback.>>

Wrong. Climate Models use a wide variety of drivers, CO2 and H20 being just two of them.

<<Now, if we propagate such a model over time, we will find exponential growth in temperature and CO2 concentration, and given enough time, the earth will get as hot as we want it. Note that we have assumed no human CO2 emissions. >>

Define "over time". Millions of years? Perhaps. But on a shorter scale (100-200 years) climate models predict a pretty stable (and even slightly decreasing) temperatures.

<<Therefore, it seems that the model predicts catastrophic global warming without the help of any human emissions. >>

The issue here is again one of time-scales. The effects (on agriculture, humans, ecosystems, etc.) of the Earth warming 1 degree Celsius over a 100 years is very different than when the Earth warms 1 degree Celsius over a 1,000 years. The warming itself is not really the issue: the rate of change is. This is a concept which many so called 'skeptics' fail to grasp.

<< I haven t heard, however, about the models predicting just how much time we do have, and how much we need to cut back.>>

Then you most likely haven't been reading the correct sources. The IPCC reports have entire chapters dedicated to how much warming climate models predict given each 'emission scenario' (SRES).

I suggest you change your sources. Here's a few to help you on your way:

https://en.wikipedia.org/wiki/Special_Report_on_Em...

https://www.skepticalscience.com/climate-models.ht...

https://en.wikipedia.org/wiki/IPCC_Fifth_Assessmen...

http://www.ipcc-data.org/sim/gcm_global/index.html

jf

they dont

they dont

With 5, no only 4, answers above this one, one, though briefly, tries for an answers to the question. I believe warmers are timidly hiding behind consensus.