[dohboi]

Succinct and to the point, as always, Agent!

Isn't there a 30 or so lag time even for the relatively 'fast' feedbacks to fully kick in? And haven't we unleashed about half of all the extra carbon we have ever unleashed into the atmosphere in just the last 30-40 years? So I'm betting we have some pretty amazing heating coming our way in the next few years and decades, no matter what we do.

(Also don't forget that, when you add in all the other GHGs, we're already at more like 480 ppm CO2 equivalent.)

Of course, we can always make things even much much worse, which is pretty much what we are doing.

I do recommend the link in the lead post, if people have time. The second Kevin Anderson lecture, 'The Ostrich and the Phoenix,' was new to me, and worth a look.

His 'optimistic' approach is basically, there's about a 99.99% chance of blowing past the 2 degree limit, so let's focus on what we would need to do to have a chance at that last .01%--basically crashing the economies of OECD countries at a rate of GDP reduction of about 15% per year for decades.

(The collapse of the Russian economy after the fall of the USSR saw under 10% reductions per year in GDP, iirc, and corresponded to huge increases in suicide and alcohol poisoning--suicide by other means--among the general population.)

[Apneaman]

This from last year says 10 years. We be finding out.


Maximum warming occurs about one decade after a carbon dioxide emission


http://iopscience.iop.org/article/10.10 ... ld.iop.org

[dohboi]

Yeah, but I think that was under rather artificial conditions, iirc. But in any case, the general point still holds.

ETA: This was the earlier study that I was thinking of. I haven't kept completely up to date on this discussion, though: http://www.skepticalscience.com/Climate ... ffect.html

I see that the abstract to your article also includes: "90% probability range of 6.6–30.7 years"

And my article is actually a simplification of Hansen's range of 25 - 50 years.

As always, assumptions going into these models can make a huge difference.

Here's another place where your study is discussed: https://andthentheresphysics.wordpress. ... m-warming/

[PrestonSturges]

I would love to see the "science" that demonstrates that 2C is a safe upper limit.

There was a pretty meaty paper a couple years ago that suggested the last ice ages were the result of only a 2 degree cooling, so the suggestion was that a change of only two degrees either way could alter the environment practically beyond recognition.

[Apneaman]

The mid-point of this is 37.5 which I have rounded to 40 years.

Global Warming Fact: More than Half of All Industrial CO2 Pollution Has Been Emitted Since 1988
PETER FRUMHOFF, DIRECTOR OF SCIENCE & POLICY | DECEMBER 15, 2014, 13:14 PM EST


http://blog.ucsusa.org/peter-frumhoff/g ... e-1988-764


We be finding out

[Tanada]

Given the roughly 30 year lag between emission and prompt effects due to the thermal inertia of the system as a whole I suspect we will emit another doubling from current totals before we make even a half hearted effort to actually stop.

[PrestonSturges]

Given human nature, we are much more likely to wait until the door has closed on all other possibilities except geoengineering. Assuming a 50 year timeline, I expect our odds are fairly good.

[Plantagenet]

I would love to see the "science" that demonstrates that 2C is a safe upper limit.

I would love to see the science that demonstrates that increasing CO2 emissions to even higher levels will cause global warming to stop at a 2°C upper limit.

There isn't any such science. The Paris meeting is engaging in magical thinking.

The 2°C "limit" is a farce. You can't stop climate change by signing a treaty or passing a law that says Temps can't go up more than 2°C. The only to reduce global warming is to reduce global CO2 emisions---which this treaty won't do.


The Paris COP conference is an exercise in magical thinking

[dohboi]

Andy Skuce has an interesting comment to the last link I provided:

Transient climate sensitivity is a function of concentrations of GHGs (a stock) not emissions (a flow).

The response to a fixed concentration of GHGs is a slow response—the “warming in the pipeline” we hear about—but the maximum response to a single slug happens sooner.

A fixed concentration of CO2 in the air requires continuing emissions.

So it sounds a bit like comparing apples and oranges.

[Plantagenet]

Andy Skuce has an interesting comment to the last link I provided:

Transient climate sensitivity is a function of concentrations of GHGs (a stock) not emissions (a flow).

The response to a fixed concentration of GHGs is a slow response—the “warming in the pipeline” we hear about—but the maximum response to a single slug happens sooner.

A fixed concentration of CO2 in the air requires continuing emissions.

So it sounds a bit like comparing apples and oranges.

It sounds like magical thinking.

There is no "fixed stock" of CO2 in the air. The amount of CO2 in the atmosphere (and in the ocean) is constantly increasing due to human FF use and CO2 emissions. Future emissions of CO2, such as those being proposed in Paris, will inevitably result in more CO2 in the atmosphere and more global warming.


There is no "fixed concentration of CO2 in the air". In the real world the amount of CO2 in the atmosphere is constantly increasing due to human FF use and concomitant anthropogenic CO2 emissions.

[dohboi]

Plant, these are studies based on hypotheticals.

The hypothetical in the main model being discussed is, if there were a sudden, one-time pulse of CO2, how long would it take for temperatures to rise and how far. That's why the term 'flow' was used of that scenario, and it was being contrasted with the 'stock' of CO2 already in the atmosphere.

I'm afraid we're mixing up discussions of physics with discussions of policies here, and confusion is sure to ensue.

[onlooker]

Well then since we are discussing a huge one time pulse and methane is known to be in the short term much more potent GHG than CO2, is it not accurate to say that shortly have a massive release of methane we would expect for temperatures to rise noticeably?

[Apneaman]

The positive self reinforcing feedbacks are numerous and new ones keep appearing - I can hardly keep up. I doubt we are aware of them all.

Spatio-temporal variability of lake CH4 fluxes and its influence on annual whole lake emission estimates

"Abstract
Lakes are major sources of methane (CH4) to the atmosphere that contribute significantly to the global budget. Recent studies have shown that diffusive fluxes, ebullition and surface water CH4 concentrations can differ significantly within lakes—spatially and temporally. CH4 fluxes may be affected at longer scales in response to seasons, temperature, lake mixing events, short term weather events like pressure variations, shifting winds and diel cycles. Frequent measurements of fluxes in the same system and integrated assessments of the impacts of the spatio-temporal variability are rare. Thereby, large scale assessments frequently lack information on this variability which can potentially lead to biased estimates. In this study, we analysed the variability of CH4 fluxes and surface water CH4 concentrations across open water areas of lakes in a small catchment in southwest Sweden over two annual cycles. Significant patterns in CH4 concentrations, diffusive fluxes, ebullition and total fluxes were observed in space (between and within lakes) and in time (over diel cycles to years). Differences observed among the lakes can be associated with lake characteristics. The spatial variability within lakes was linked to depth or distance to stream inlets. Temporal variability was observed at diel to seasonal scales and was influenced by weather events. The fluxes increased exponentially with temperature in all three lakes, with stronger temperature dependence with decreasing depth. By comparing subsets of our data with estimates using all data we show that considering the spatio-temporal variability in CH4 fluxes is critical when making whole lake or annual budgets."


http://onlinelibrary.wiley.com/wol1/doi ... 2/abstract

[Apneaman]

Simpler way to estimate feedback between permafrost carbon, climate
Scientist leads effort to shed light on a potentially huge player in the planet's climate
Date:
October 5, 2015
Source:
DOE/Lawrence Berkeley National Laboratory
Summary:
A simple model of permafrost carbon based on direct observations has been developed by a team of scientists. Their approach could help climate scientists evaluate how well permafrost dynamics are represented in Earth system models used to predict climate change.


"One of the big unknowns in predicting climate change is the billions of tons of carbon frozen in Arctic permafrost. As global warming causes soil temperatures to increase, some of this carbon will decompose and enter the atmosphere and accelerate climate change."

http://www.sciencedaily.com/releases/20 ... 132854.htm

[Lore]

Given human nature, we are much more likely to wait until the door has closed on all other possibilities except geoengineering. Assuming a 50 year timeline, I expect our odds are fairly good.

Which is why I contend we are a failed species in waiting. The geoengineering thing will be just a Hail Mary pass in the end. A last gasp attempt as it were. Producing little to none, or chaotic results.

The whole discussion is rather an exercise in futility since the markers are constantly moving. The milestone of 2100 is only a subjective fixed date. The climate change, which we have set in motion, will swallow that up and continue to move beyond it for many thousands of more years.

[onlooker]

Yes but we will almost certainly not be around to witness what we have wrought, being the continued warming of the Earth.

[Lore]

Anything put down here will be lost in cyberspace over time when the whole system goes down. So yes, we can enjoy our current discourses, but posterity will have far and more pressing things to worry about then the past tense of unsolvable human rectitude.

[dohboi]

Good point, ol. Even though the study was for CO2, I would think that the general slopes for those graphs would be pretty similar for CH4. The effect of a mega-burp from either clathrates or permafrost or (God help us) both, would be felt in years--we wouldn't have to wait decades.

[Subjectivist]

Good point, ol. Even though the study was for CO2, I would think that the general slopes for those graphs would be pretty similar for CH4. The effect of a mega-burp from either clathrates or permafrost or (God help us) both, would be felt in years--we wouldn't have to wait decades.

God gave us a beautiful self sustaining garden. We mucked it up from pole to pole.

[PrestonSturges]

Given human nature, we are much more likely to wait until the door has closed on all other possibilities except geoengineering. Assuming a 50 year timeline, I expect our odds are fairly good.

Which is why I contend we are a failed species in waiting. The geoengineering thing will be just a Hail Mary pass in the end. A last gasp attempt as it were. Producing little to none, or chaotic results.

The whole discussion is rather an exercise in futility since the markers are constantly moving. The milestone of 2100 is only a subjective fixed date. The climate change, which we have set in motion, will swallow that up and continue to move beyond it for many thousands of more years.

I expect it will still be TEOTWAWKI, but as much as a third of the population might survive.