I think that needs to be clarified. What is not known with certainty is the climate sensitivity after feedbacks. The fact that adding CO2 to the atmosphere increases surface temperature has been known for almost 200 years.

This was something that I recall James Lovelock commenting upon, i.e. the scope for geo-engineering to mitigate AGW.  His point was that there will always be winners and losers from attempts to engineer such mitigation and the losers, or perceived losers, would be against the plan.  Plus of course there is always the law of unforseen consequences.

I suppose that, having got ourselves into this position the pressure to find technology-based mitigation actions is inevitable.

I don't like the idea of geoengineering, it's like prodding a sleeping giant with a stick. We should use it as a last resort only.

Also, it only solves one small piece of the puzzle. It doesn't solve:

1) Ocean acidification

2) All pollution that goes along with emissions of CO2 (sulphates, nitrous oxide, low level ozone etc)

3) Deforestation and land use issues

4) Energy inefficiency

5) Lack of energy diversity

and probably some more I've forgotten. 

I don't like it either. I think it has the potential to cause war.

Good points by both of you - and much in line with my thoughts.

I think it is inevitable that something will be attempted because (a) our 'supertanker' of a world economic system will take an age to slow down and turn, so technology-driven mitigation efforts are going to have to feature in the range of actions, and (b) it seems to be deeply in our approach to thinks to attempt to change nature to our will rather than live with nature. After all we have spent much of our history trying to gain control over the natural world with varying degrees of both success and failure and capabililty.

As for prodding a sleeeping giant, arguably we are doing that anyway, aren't we?

Geoengineering is a curious subject. It has been discussed for many decades in terms of it's potential for 'terraforming' other planets for human habitation and there is much written about it both in the scientific sense and as science fiction.

One of the essential techniques at the heart of terraforming is the deliberate addition of greenhouse gases to a planet's atmosphere to control its surface temperature and bring it within habitable bounds. Quite a paradox when one considers some of the arguments made about AGW on Earth.

http://en.wikipedia.org/wiki/Terraforming

As you can see, a lot has been written on the subject.

In terms of geoengineering on Earth, there are several factors to consider. These are broadly outlined in the Wikipedia page on Geoengineering:

http://en.wikipedia.org/wiki/Geoengineering

What is clear even from a superficial reading is that such techniques are immensely resource (and particularly energy) intensive. They assume that the outcomes of such interventions can be modeled and therefore predicted accurately. Perhaps the most unsettling aspect is that some of the techniques are capable of being weaponised.

There is one further point of note in any preliminary discussion about geoengineering in the context of AGW mitigation and that concerns the economic risk profile of the techniques and how the contractual responsibilities change with them. Most discussion of the subject revolves around 'carbon capture' and the two types of technique proposed are capture 'at source' involving modifications to emission sources and more generalised 'open air' methods which aim to process sufficient quantities of air away from emission sources to reduce the overall greenhouse gas load.

The regulatory and commercial models available for 'capture at source' are relatively simple. In these scenarios, the emitter takes responsibility for the capture and sequestration of the emission by products, bears the cost of doing so and passes the cost on to the consumer. Dealing with emissions 'at source' is technically much simpler and more energy efficient than 'open air' methods. It also clarifies responsibility because the emitter cleans up their own emissions and the cost of doing so is passed on directly in the cost of the product.

When we consider the methods for open air capture, things become less clear. They involve the application of techniques remote from the emission source and must therefore deal with reactions at much lower concentrations. This means the techniques are applied on a much larger scale and it is not clear whose emissions are actually being captured. The assumption is that open air capture schemes would be carried out by governments and funded by the taxpayer opening the way for those with more aggressive lobbyists to win concessions and unfairly redistribute the already much higher costs. An additional layer of beauracracy and obfuscation of responsibility via the tax system further reduces the economic efficiency of the arrangement.

The same problems of divided and indistinct responsibility also apply to techniques such as orbiting mirrors, iron seeding of the ocean, albedo modification etc. Essentially the 'at source' capture methods make much more sense than any sort of large scale attempt to mess with other aspects of the ecosphere because they are more efficient and accurately assign costs to production.

"The way to ruin is rapid."

That makes for an interesting juxtaposition....

Best to hope that one of those statements is wrong.

Of course the Hubbert curve combined with the exponential growth described by Bartlett (on which most of our economic systems are predicated) will produce both gradual depletion of production AND instantaneous societal collapse. They could both be correct.

I hope I am not alive to find out who is right.

In another thread, Stephen Wilde said:

"I accept that no non condensing GHGs would result in a cooler troposphere but the system energy content need not change because the water cycle would just slow down to retain system equilibrium energy content"

I don't see how this statement can make sense. So the troposphere cools down, and so to keep system energy content constant (which is what I understand by 'retain(ing) system equilibrium energy content') then the oceans must warm up.

So how can the water cycle slow down if the oceans are warmer and the troposphere cooler, a situation that simply must result in a faster water cycle due to increased atmospheric instability?

If Stephen were correct there'd be no Pembrokeshire Dangler for starters!

Cheers - John

If non condensing GHGs reduce then there is less energy in the equatorial air masses to push the jets poleward.

Therefore whatever the sun is doing at the time the jets are more meridional/equatorward than they otherwise would have been.

Therefore global cloudiness is a bit higher and less solar energy gets into the oceans so the oceans gain energy from the sun more slowly and the entire flow of energy through the system slows down which maintains overall system energy content.

Reduced solar energy into the oceans is matched by reduced rate of energy flow from oceans to air to space.

However there is only so far one can go with that which is why cooling is more dangerous than warming. If solar input to the oceans drops a lot (Milankovitch cycles) then ice cover expands and ADDS to the albedo effect of more clouds.

Nonetheless there has never been runaway cooling because the sun has been slowly increasing in energy output over the past 4 billion years as per the faint sun paradox.

If non condensing GHGs increase then the opposite process occurs. More energy gets into the oceans but the water cycle speeds up to eject it to space faster. The system has never reached a tipping point despite far higher CO2 levels in the distant past. The variability and power of the water cycle at current atmospheric pressure has been able to handle everything thrown at it since the oceans formed.

I feel like what you're describing here is climate change as a method of planetary homeostasis - which it actually is. But in doing so you're claiming the symptom cures the disease.

You're right that climate responses limit Earth's temperature to within a certain range, however not all of that range is beneficial for human life and infrastructure as we've developed it over the last couple of hundred years.

As for a tipping point, you may have misunderstood what 'tipping point' means in the context of AGW - one example would be the release of methane from thawing permafrost. It's a tipping point in that it releases a powerful positive feedback, but it does not result in 'runaway' global warming where the planet gets hotter forever. It just means the equilibrium temperature gets warmer than it would otherwise be.

I don't see the air circulation response as a symptom but as the 'cure'.

In light of the thermal efficiency of the air circulation response the system variability as regards total energy content is limited to a very narrow range.

The necessary response to deal with human emissions would be infinitesimal as compared to natural variability.

"It just means the equilibrium temperature gets warmer than it would otherwise be."

I don't think that happens because global temperatures have been so stable for such long periods of time in paleological terms.

Instead a burst of methane release would just result in a slightly faster or larger water cycle with a shift in the surface air pressure distribution. That would be small in terms of natural variability such as that from MWP to LIA to date.

The system response is the same as regards ANY forcing and the effect of the response is to maintain total system energy content.

All we have to ascertain is the scale of the system response to human emissions as compared to natural changes and on all the available evidence it is miniscule.

I think that this will be the most important of the AGW issues;

ABSTRACT FINAL ID: GC41B-0794


TITLE: Ebullition-driven fluxes of methane from shallow hot spots suggest significant under-estimation of annual emission from the East Siberian Arctic Shelf


SESSION TYPE: Poster

SESSION TITLE: GC41B. Permafrost and Methane: Monitoring and Modeling Fluxes of Water and Methane Associated With Arctic Changing Permafrost and Coastal Regiona I Posters



AUTHORS (FIRST NAME, LAST NAME): Natalia E Shakhova1, 2, Igor Peter Semiletov1, 2, Anatoly Salyuk2, Chris Stubbs3, Denis Kosmach2, Orjan Gustafsson4

INSTITUTIONS (ALL): 1. IARC, Univerrsity Alaska Fairbanks, Fairbanks, AK, United States.
2. Laboratory of Arctic Research, Pacific Oceanological Institute FEBRAS, Vladivostok, Russian Federation.
3. University of California, Marine Science Institute, Santa Barbara, CA, United States.
4. Institute of Applied Environmental Research, Stockholm University, Stockholm, Sweden.



Title of Team:


ABSTRACT BODY: The high-latitude, shallow ESAS has been alternately subaerial and inundated with seawater during glacial and interglacial periods respectively. Subaerial conditions foster the formation of permafrost and associated hydrate deposits whereas inundation with relatively warm seawater destabilizes the permafrost and hydrates. Our measurements of CH4 in 1994-2000 and 2003-2010 over ESAS demonstrate the system to be in a destabilization period. First estimates of ESAS methane emissions indicated the current atmospheric budget, which arises from gradual diffusion and ebullition, was on par with estimates of methane emissions from the entire World Ocean (≈8 Tg-CH4). Large transient emissions remained to be assessed; yet initial data suggested that component could increase significantly annual emissions. New data obtained in 2008-2010 show that contribution of ebullition-driven CH4 fluxes from shallow hot spots alone could multiply previously reported annual emission from the entire ESAS.

Anyone showing that other 'warm periods' drove such releases will help convince me that todays extremes are just 'normal' workings of climate.

Any takers?

Article here, source is paywalled
http://www.forbes.com/sites/larrybell/2012/01/10/global-warming-no-natural-predictable-climate-change/

I am dismissive of that diagram based simply on the timescales used. If he wishes to compare his model with global temperartures he needs to go back at least as far as the begining of the stellite record (1979) or the instrumental record of surface data. The fact he only goes back to 1996 to compare his model with observations suggest to me that it doesn't work very well.

I am dismissive of that diagram based simply on the fact that it is a copy of Theodor Landscheidt's work. Astrological prediction doesn't carry much weight in science!

Cheers - John

More details here. Perhaps somone can explain his methodology.

Perhaps the guys at WUWT should ask him to publish his source code... 

On WUWT they even show the full graph:

Notice anything(s) odd in comparison with the one Four so desperately wishes us to be gospel??

We can ignore the post-observational part if we like, as these are model-based and we are often told how useless models are.....

Cheers - John

I haven't looked at WUWT for weeks but it is on there in more detail
http://wattsupwiththat.com/2012/01/09/scaffeta-on-his-latest-paper-harmonic-climate-model-versus-the-ipcc-general-circulation-climate-models/#more-54492 

The Geologist responsible for this will need excommunicating too
http://wattsupwiththat.com/2012/01/11/the-portland-state-university-study-of-shrinking-mt-adams-glaciersa-good-example-of-bad-science/