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Getting ready for 1100 °C greenhouse runaway Earth

The current global average mean temperature is about 15 °C. However, Colin Goldblatt and Andrew J. Watson have submitted a preprint called

The Runaway Greenhouse: implications for future climate change, geoengineering and planetary atmospheres
to the Royal Society which discusses a balmier temperature that we may expect soon: 1,100 °C. In such a temperature, you won't need a sweater.

Of course, the process by which this outcome will be achieved is the "runaway greenhouse effect". It gets warmer, so some oceans will evaporate and water vapor will get more abundant in the atmosphere. This water vapor will induce extra warming, and so forth. The equilibrium temperature may only be reached near 1400 K because that's where the water vapor no longer absorbs a sufficient portion of the thermal radiation.

The authors expect this great outcome to be reached in 2 billion years because the solar output will increase by a sufficient amount, as the Sun is getting closer to its red giant phase in about 7 billion years. However, may it happen that we will actually switch to the 1100 °C Earth earlier?

Of course, the right way to heat the Earth by 1100 °C is to burn a few tons of fossil fuels. The authors try hard to prove that we may soon warm the Earth by 1100 °C but they fail. Despite all the crazy assumptions they are willing to make, it seems impossible to heat the blue planet this much.

But they had already worked out some mitigation strategies – recipes how to avoid the warming by 1100 °C – so they include them in the paper, nevertheless, for the case that their analysis is wrong and we will get a 1100 °C warming soon, after all. ;-)

You couldn't make it up.

It's remarkable how unfocused similar papers are. Analyzing whether the Earth may start some runaway warming in 2 billion years is surely an interesting and legitimate (albeit purely academic) question. In the case of our planet, the dominant greenhouse gas would have to be the water vapor. There doesn't seem to be a sufficient amount of alternatives available.

But why the hell do they mix this question with some preposterous speculations about the present era which clearly doesn't allow any runaway behavior of this sort and with CO2 that has clearly nothing to do with this hypothetical effect? And why do they discuss "mitigation strategies" for a scenario that contradicts the results of their own research?

Water vapor is the main greenhouse gas and it is even the "executor" of most of the (nonsensically) high climate sensitivity as imagined by the IPCC and similar deluded pseudoscientists. It is needed to obtain the positive feedbacks, to increase the negligible no-feedback sensitivity caused by the CO2 itself.

It is doubtful whether the net feedback is actually positive; effects related to clouds may make it negative and the empirical data are more compatible with the negative sign. However, what is certain is that this feedback isn't in the "runaway" range. Note that the original warming may be strengthened by feedbacks described by a dimensionless constant, \(f\). The total factor of strengthening, including feedbacks-to-feedbacks, feedbacks-to-feedbacks-to-feedbacks, and so on, is
\[ 1+ f + f^2 + f^3+\dots = \frac{1}{1-f} \] If \(f\) is positive, the factor above exceeds one, so you get a stronger effect than the initial one. If \(f\) is negative, the original effect is weakened. However, if \(f\) is not only positive but exceeds one, then the left hand side of the equation above diverges and the right hand side, which isn't the "obvious" sum of the divergent series, is formally negative. That's the situation in which the initial perturbations exponentially grow with time instead of being weakened.

We're clearly observing that this isn't happening. It wasn't happening for billions of years. Quite generally, if \(f\) were greater than one or even smaller than one but close to one, we would have to see that the climate is extremely sensitive and its temperature brutally changes when the energy flows change just a little. This is not our Earth.

Now, \(f\) may be temperature-dependent itself. The "effective laws of physics" may get sufficiently different in very different conditions. But one has to be careful about these calculations and include all other changes that could occur, such as the changes to the albedo and chemical composition of the atmosphere. At any rate, we know that conditions that resembled anything we had in recent billions of years guarantee \(f\) smaller than one. And during that time, the concentrations of CO2 were as high as 6000 ppm or higher.

So I guess that the actual calculation of the hypothetical processes in 2 billion years when the runaway greenhouse may or may not materialize isn't really the genuine core and purpose of the paper. The real motivation of all such papers is the fear that the authors induce even if their conclusion says that the runaway greenhouse can't happen anytime soon. It's the very fact that these crackpot scenarios may be considered by people who are employed by universities which is important for the publication of all such materials.

If I were responsible for such issues, I would fire every single researcher who has ever come close to this stunning politically-driven garbage research. For their deliberate promotion of the irrational fears and of the unscientific reasoning in the public and sometimes even the scientific public, these people deserve to die of hunger.

Via Physics arXiv blog

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snail feedback (2) :

reader gogol de kapote said...

incorrect...Venus have only 450ºc

and 90 atm pressure full of CO2

1100ºC only if the sun go red...

the average is snow today

und no rain since December 19,4 mm only

and the tchéques are full of frozen water

no hay josef

we want the klimasturz now...

reader gogol de kapote said...

and most of the CO2 is down under...only in limestones the CO2 exceeds 1000 times the CO2 of fossil fuels...coal included (CH4 excluded )

water 4km x 330,000,000 km2
1,300,000,000 km3 of water

at 450ºC how much water go in the outerspace?

h20 co2 molecular weight and scape velocity...and i say no more
(nor less...noor from jordanie..)