EnviroLink Forum

Again, other than the examples provided in the graph, there are none which can be documented because they are not common nor are they good for living things. The main difference between the "normal" feedback and the "runaway" version is the extent to which the temperature can accelerate. As in the example of the Arctic tipping points, one point might be considered a "normal" feedback event but when one triggers another, which combined triggers another, that is a "runaway" situation. We cannot control it nor is there a simple natural event that would control it for any timeframe other than short term, such as a couple of years. Multiple events would be required to have any control over a period longer than a few years. The runaway version is more likely to cause a temperature change which results is extinction due to the inability for flora and fauna to adapt because it is more rapid due to the passing of the tipping points.

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Which don't tell us anything about their source.


Or that are documented which is my impression.

So if somebody comes up with a runaway that is documented or strongly suggestive from clear paleo-indicators I would be interested in seeing them.


Let's make it simple and modest - two degrees cent. of warming based on a series of feedback events - CO2, methane, water vapor, ice melt, warming ocean etc - all feeding off each other(Outside nonfeedback forcings don't count). Any evidence for that?

As I indicated earlier, one of my reasons for doubting this internally driven runaway scenario is the exponential rate for the earth to release heat as the warming increases linearly, only partly overcome by increased ghgs.

Specifics, no. There are quite a few things which fall into that category because they have never happened in human history to be documented for us. Of course, some would have eliminated us as a species and the point would have been moot.



So you do not believe the graph you referenced and thus there is no documentation? You have trumped everything with a personal belief.



Clear paleo-indicators from tens of millions of years ago for specific causation? All you will need is a time machine.



Not that you will believe because it does not happen in nature very often. Maybe once every 50 million years on average.



Not sure what you are trying to say. The earth does not release much heat in comparison to the energy retained by the GHE.

What do you think happens to the heat retention capacity if there is a very significant release of stored methane from any one of the sources listed?

​Methane emissions from warming sub Arctic peat rich wetlands

​Methane and carbon dioxide emissions and from thawing permafrost

Methane emissions from sub sea floor frozen solid methane gas hydrate

Logic tells me that it will cause a significant increase in the retention of energy for the period of time following, which most likely could cause another of the sources to also have a significant release. There are a lot of things which come into play at the poles which can be confusing. Water vapor pressure is lower so the energy retention of the other GHGs is higher, which is often lost in the discussion of the global effect. The IR retention band is also different for CO2, N2O, and CH4 so there is even a global difference as well.

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“Intellect is invisible to the man who has none”
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If the whole business of runaway warming is subjective, obscure and unprovable then why assert it? It seems the concept simply lends itself to the one criticism that seems to stick to a lot of folks associated with promoting concern for AGW; some seem to have an addiction to catastrophic scenarios beyond what the evidence presents.

Again, it doesn't have to be Wayne, but if anyone can steer me to scientifically sound evidence for a self-generated runaway scenario I'd be interested in seeing it. Wayne wants to make it about me but as far as evidence he comes up with nothing.

From Wayne's link;
"The runaway Arctic +ve feedbacks​​​​​​​​​​​​​​
•Loss of Arctic snow and summer sea ice cooling albedo

•​Methane emissions from warming sub Arctic peat rich wetlands

•​Methane and carbon dioxide emissions and from thawing permafrost

•Nitrous oxide emissions from thawing permafrost

•Methane emissions from sub sea floor frozen solid methane gas hydrate"
http://www.climateemergencyinstitute.com/runaway.html
Then this; http://e360.yale.edu/feature/tipping_po ... mers/2567/
and this; http://www.pnas.org/content/106/49/20596.full
this; http://www.the-cryosphere.net/7/275/201 ... 5-2013.pdf
related; http://www.ecology.com/2012/03/19/risin ... -high-co2/
also; http://www.ecosystemresearch.org/tippin ... 3%2007.pdf

Similar to my fourth tipping point thread. It seems this is the way it is unfolding; Many times over the Earth absorption ability HGHGs-->ocean and Arctic warming, and greater open ocean warming, until open ocean warming from ice loss in the Arctic becomes an unstoppable positive feedback loop-->Arctic warming reaches the completion of its positive feedback loop or methane self-release-->ocean warming lets off even more methane until it also is a completed positive feedback loop-->water vapor from breaking down methane and from increasing heat also is a positive feedback loop-->release of CO2 from dissolution with water and on land in a further positive feedback loop.
Where will equilibrium be? Does it really matter? Young people now will witness very quick change in climate and even quicker change in civilization from population crash and ecological collapse. Misery followed by extinction on Earth.

But in the meantime, we can enjoy her while she lasts.

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Because by the time it can be proved to any degree of accuracy it is too late for anything to be done about it. There is evidence of the runaway effect, of the climate change causing massive disruption with human civilization, of climate change causing major levels of extinction, and even of human influence in climate change. The big problem is that as far as humans are concerned, this is ALL uncharted territory. We have never experienced anything similar in the recorded history of the species.



Again, other than the information on the methane releases in the Arctic? There are measurements showing an increase in methane concentration in the atmosphere after a lull, there are measurements indicating increading emissions of methane from the tundra, there are documented melting issues with permafrost being less "perma" than before.




The part about you is your bypassing of the evidence because it does not fit your definition.

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With friends like Guido, you will not have enemies for long.

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"The difference between genius and stupidity is that genius has its limits."
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You haven't come up with an iota of evidence, just a spike without any determinable cause. The burden is on the person who asserts a proposition and you have flunked the test and just divert by pretending I'm denying evidence. I came on here asking folks to show me the evidence, not to emphatically deny the runaway effect.

Forget Wayne and his games, anybody want to present some real evidence?

Since the sudden burst of methane is the scenario that is generally presented by the runaway catastrophe folks this link from the National Academy of Sciences that JE offered is interesting. They pretty much have warming causing methane to dribble out over a long period of time, consistent with a more normal feedback scenario, not a runaway scenario. Read it at your leisure.

http://www.pnas.org/content/106/49/20596.full

You asked for someone to present the evidence for the definition YOU choose to give rather than the definitions used in the references.

The same situation held true for Arrhenius when he first presented his calculations on human induced warming because there had never been a human induced warming to use as evidence. The possible natural effects were (and still are) relatively undocumented.

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With friends like Guido, you will not have enemies for long.

“Intellect is invisible to the man who has none”
Arthur Schopenhauer

"The difference between genius and stupidity is that genius has its limits."
Albert Einstein

Did you happen to notice in this discussion of ONE source of methane almost 20 years ago now, there was only the potential impact of warming due to CO2 affecting ocean temperature? The release of methane from the other sources listed change this variable in proportion to the amount of methane released.

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With friends like Guido, you will not have enemies for long.

“Intellect is invisible to the man who has none”
Arthur Schopenhauer

"The difference between genius and stupidity is that genius has its limits."
Albert Einstein

I agree with Dingo. Runaway warming would imply that the equilibrium climate sensitivity would be much higher than the accepted mainstream values between 1.5 and 4.5 K/doubling. Positive feedbacks eventually reach an equilibrium. Each additional "loop" becomes weaker than the positive feedback loop before it. If an initial increase of Carbon Dioxide caused 1.5 K of warming, and positive feedbacks from that initial warming caused an additional 0.8 K, then those additional positive feedbacks from the warming would cause an additional 0.4 K, and those would cause additional warming of 0.2 K, then 0.1 K, 0.05 K, 0.025 K etc. So even though net feedbacks are weakly to strongly positive in the climate system, runaway warming is unlikely. This is why we get a value between 1.5 to 4.5 K for ECS, and not infinity Kelvin.



And there are additional positive feedbacks that we have yet to uncover, like the permafrost feedback. But those would work in the same way as described above.

I don't like linking to blogs, but Skeptical Science has a really good article on why net positive feedback does not imply runaway warming.

http://www.skepticalscience.com/positiv ... vanced.htm

You are referencing CO2 feedbacks, not methane release and those associated feedbacks, which is a different discussion all together.

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With friends like Guido, you will not have enemies for long.

“Intellect is invisible to the man who has none”
Arthur Schopenhauer

"The difference between genius and stupidity is that genius has its limits."
Albert Einstein

Again, a completely different discussion because the release of significant amounts of methane is not considered a "feedback" in those discussions. The CO2 temp increase, causing more H2O vapor, which causes another increase in temperature and causes slightly more CO2 and H2O vapor is the positive feedback. The release of methane in the Arctic, which is the more probable scenario, is another trigger and not a feedback on CO2.

This is also dealing with the ultimate "Venus Effect" which is not the definition of runaway warming Hansen was using. The "runaway" is where the temperature is affected by the passage of a critical tipping point which prevents any human control of the factors controlling that increase.

_________________
With friends like Guido, you will not have enemies for long.

“Intellect is invisible to the man who has none”
Arthur Schopenhauer

"The difference between genius and stupidity is that genius has its limits."
Albert Einstein

I'm no expert on the distinction between a "trigger" and a "feedback" but for the purposes of this discussion it appears to be a distinction without a difference. If the CO2 and water vapor tandem create a warming effect that releases methane then it becomes part of the feedback system clearly and as such produces a feedback of CO2 and water vapor with the cycle diminishing steadily to equilibrium as Snowy has laid out.