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wili

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Toward a complete list of climate feedbacks
« on: August 25, 2013, 07:56:54 PM »
These are both consequences and causes of further GW. (If mods want to shift this to the Science section, that's fine.) I have been trying to assemble as complete as possible a list of climate feedbacks as I have come across them over the years. This is a brief list, without citations attached, but I could supply those easily in most cases if anyone is interested.

I would love to hear people's comments, additions, critiques...Obviously some of these are both more major and more certain than others. Ultimately it would be good to try to rank them, but that difficulte (impossible?) task will have to wait. For now I just want to know if I am missing any major ones, or if people think any I have here are completely off (or wrong sign!).

“Positive”--exacerbating

charney = “fast” feedbacks:
--albedo change with loss of land and sea ice and snow (stops when all snow and ice gone)
--water vapor
--cloud (both ways?)
--lapse rate (though this may also cut both ways?)

non-charney “slow” feedbacks:
   carbon feedbacks
--forests, grasslands, peat dry up and burn/die>CO2
--“  “    get bugs/diseases, die>termites>methane; die>burn
--soils, already weakened from above, wash away with increasingly extreme downpours, leaving no medium for plant that could absorb CO2 to grow
--terrestrial soils dry up>CO2 methane “If the bank of carbon held in the world’s soils were to drop by just 0.3 percent, the release would equal a year’s worth of fossil fuel emissions”
--permafrost melts—release CO2&methane from new bacterial activity/ free methane from deeper reservoirs, starts to (net) release rather than absorb (sink) C
--melting Greenland and Antarctic icecap uncovers same
--feedback combo: Each extreme weather event leads to less CO2 absorption, leads to more warming, leads to more extreme weather events, leads to....
--sea bed permafrost, clathrates, free methane
--sea surface increased activity of methanogens
--newly flooded areas from sea level rise become new swamps—more methane
--as atmospheric humidity increases with global warming, the amount of high troposphere ice particles will increase, and as these ice particles generally serve to reduce the rate of methane oxidation; this implies that with increasing global warming, the global warming potential, GWP, of the methane in the atmosphere over the Antarctic will increase.
--Rising CO2 In Atmosphere Also Speeds Carbon Loss From Forest Soils
--newly ice-free Arctic ocean erodes islands and coastlines releasing carbon in soils
--warming ice encourages dark cryophilic bacteria which alters albedo
--Trees excude CO2 rather than taking it in
--Sudden switch from a three cell NoHem system to a one cell system because of loss of temp differential between equator and No Pole. One cell will transport heat from equator to pole much more efficiently.
--if methane reaches a big enough level in the atmosphere, its average time aloft starts going up, because saturation point is reached to where there's not enough OH around in the atmosphere so that methane can be split apart that way
--warmer ocean absorbs less CO2
--warmer oceans kill phytoplankton that otherwise sequester CO2
--draw downs behind damns during (CC induced) droughts increases methane release

   Other:
--drought, an expected outcome of GW, can increase intensity of heatwaves
--end of change of state--when all ice gone in a region, no more heat sucked up by its melting
--newly open Arctic Ocean evaporates more H2O (a GHG) (but open ocean can also absorb more CO2)
-- Stripping of Oxygen from the Oceans
--melting permafrost releases NOX
--accelerating albedo shift with black carbon (soot) concentrating on surface as melt goes on
--accelerating albedo shift with more trees growing in the tundra; now happening faster than once thought, since many ‘shrubs’ native to and widespread throughout the tundra grow into trees as conditions warm
--uplift from isostatic rebound as Gr icesheet melts changes angle to greater slope down which ice slides faster
--similar activity could cause local earthquakes which may increase collapse of fragile ice
--Loss of GIS accelerating as highest areas melt down to lower, warmer areas, not only increasing sea level (see above), but also hastening the time when there will be no more ice cap to absorb hundreds of quintillions of joules of energy as it melts (see above)
--More wild fires also means more soot in the air which further changes albedo of ice and snow, leading further to the effects mentioned immediately above
-- Bigger storms from GW cause updrafts to carry moisture all the way into the stratosphere, reducing ozone and creating more ghg (water vapor) into part of the atmosphere that has very little of it.
--Hadley cells shift "so that air is being pulled along the earths surface from mid latitudes towards the Arctic... more soot and dust will accumulate on the remaining ice including on Greenland."
--Reversal of the Polar Vortex
"Putting together the above information, we see what powers the polar vortex.  As the Arctic air radiates heat into space, it sinks, sucking high altitude air toward the poles.  Coriolis effect skews this flow of air to the right so at high latitudes, on the surface of the earth there are North East winds (flowing towards the South West).    With more and more heat being absorbed by an ice free Arctic ocean and transmitted to the air, this circulation pattern should reverse.  This would be expected to bring a huge flux of warm air from the south which would exacerbate the effect and cause sudden extremely warmer conditions in the Arctic for the months in question. These will be South West winds (flowing toward the North East)”
--As beetles and other diseases move north aided by GW, the number of sick trees increases rapidly. The levels of methane these emit can be high enough to ignite
-- mixing has an immediate effect upon ice through churning rather than the longer term greenhouse effects from bubbling methane, which of course opens up more water which, through albedo, warms up the water, which radiates down to liberate more methane…
--Loss of GIS and other ice sheets (as well as other shifts in water on land –drying and flooding…) lead to tectonic shifts and increased eruptions of volcanoes—releasing carbon that leads to likely longer-term warming (though their aerosols and other particles will lead to a temporary cooling).
--Oceans that grow more acidic through Man's fossil fuel burning emissions, can amplify global warming by releasing less of a gas that helps shield Earth from radiation http://phys.org/news/2013-08-science-global-source-sea.html (Thanks to johnm33 for just posting this one on the science thread, though as ccg points out, it is unclear if they are talking about direct aerosol shielding, or about increased cloud formation.)
 


Human responses:
--war
--AC
--denial
--geo—engineering attempts gone bad
--more and more people moving to avoid consequences of GW—refugees, both burning oil to move and burning ff to build new cities…
--more and more ff-fueled infrastructure built (sea walls, etc) to stave off effects of GW…
--aerosol—as we turn away from coal in response to GW (and clean up aerosol pollution from those that remain), the ‘aerosol parasol’ goes away causing and essentially immediate global temp increase of .5 – 2 degrees C. (see below)
--rush to ever dirtier sources with lower EROEI—tar sands, low grade coal, deepwater oil…
--Rivers dry, barges can’t haul material—more sent by more ff intensive truck and rail
--newly ice-free Arctic leads/has lead to more ff extraction/burning as well as new oil spills, and perhaps activity that further accelerates methane hydrate (and other methane) release

Negative (=damping) Feedbacks (and related dynamics)
--black body radiation ^4, Planck and all that
--clouds (?)
--weathering of rock, mountains; the reaction SiO3 + CO2 > CaCO3 + SiO2 (?)  runs faster in  a warmer climate (but this effect is limited by the amount of exposed rock available, so it is a very slow feedback)
--ocean absorption
--same enhanced in Arctic by loss of sea ice
--a more ice-free Arctic may directly absorb more CO2 into its waters
--desertification alters albedo so more light reflected into space(?)
--increased biological activity in warming permafrost and tundra (overwhelmed by other factors?)
--lapse rate--as heat and moisture get distributed more evenly through the whole air column, it can more easily be radiated into space (help needed here)
--Loss of GIS and other ice sheets (as well as other shifts in water on land –drying and flooding…) lead to tectonic shifts and increased eruptions of volcanoes—whose aerosols and other particles will lead to a (temporary) cooling (but likely longer-term warming).
----flooding and deepening of continental shelves increases the activity of the ‘continental shelf pump’ which moves particulate carbon off of the shelf (where it might eventually get back into the atmosphere) down into the deep sea, where it is likely to remain for a very long time.
--SLR increases pressure on subsea clathrates keeping them stable (but not as fast as ocean temperatures increase?)
--some plants growing faster with increased atmospheric CO2 (overwhelmed by predominantly negative effects of GW on plant growth?)

Human response(??)
--as major impacts kick in, global PTB or general population wakes up and drastically decrease ff burning...(dream on)
--planting native grasses in mid latitudes, trees in tropics, terra-preta (?)
--geo-engineering (very likely to very wrong—best in other side)
--eating less meat, traveling less (esp by plane), consuming less, make fewer babies…
--alt energy, because of promotion through policy, economic tipping points, or a combination, rapidly replace nearly all ffs (are we seeing the beginnings of this??)
--major breakthroughs in C sequestration technology that can be rapidly built out with minimal use of ff (but this could prompt 'moral hazard' behavior, and in any case seems rather a techno-fantasy than an even remote likelihood)
--revolution (could go either way?)
--grimmer—gw leads to widespread shortages of basic food supplies—mass starvation, fewer using ff-powered machines…; econ collapse…same (BUT economic collapse also could lead to big drop in coal plant emissions—good in the long run, but in the short run, this would quickly bring down aerosol emissions. Aerosols have been working as a “parasol,” blocking sunlight from entering the lower troposphere, so keeping us perhaps 2 degrees C cooler. So with this removed, we could see a sudden increase of 2 degrees, which could set off other positive feedbacks discussed above.)

.........................

Please add more of your own in any category (or create a new category!?), or critique any of the above.

--

--
« Last Edit: August 26, 2013, 02:01:27 PM by wili »

Survival Acres

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Re: Toward a complete list of climate feedbacks
« Reply #1 on: August 27, 2013, 05:58:13 AM »
You forgot the big one.

Extinction.

wili

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Re: Toward a complete list of climate feedbacks
« Reply #2 on: August 27, 2013, 06:26:59 AM »
If there is anything I am more obsessed with than feedbacks, it is extinction.

But perhaps you could clarify what you mean. Is there a particular extinction that you see as a "positive" (exacerbating) feedback to GW. Or do you mean when humans go extinct, that will represent a negative (damping) feedback on GW?

Meanwhile, this just came out at CP:
http://thinkprogress.org/climate/2013/08/26/2525901/ocean-acidification-amplify-global-warming/

Ocean Acidification May Amplify Global Warming This Century Up To 0.9°F

It looks like what I just added to the end of my "other" (not exclusively C cycle) positive feedback sublist that johnm33 posted on in the science thread. Still not sure how cloud formation might figure into this.

ritter

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Re: Toward a complete list of climate feedbacks
« Reply #3 on: August 27, 2013, 05:30:01 PM »
You forgot the big one.

Extinction.

That would be a useful negative feedback, but only if it were to occur before we've liberated all the stored carbon. And nobody would be around to see if it worked!

Sigmetnow

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Re: Toward a complete list of climate feedbacks
« Reply #4 on: August 28, 2013, 02:44:51 AM »
Another possible Human response:  migration off-planet (for a select few).  To Low Earth orbit, the Moon, or Mars.

wili

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Re: Toward a complete list of climate feedbacks
« Reply #5 on: August 28, 2013, 03:42:16 AM »
Good point, S. Of course, every space shot sends huge amounts of CO2 and other GHG's into the atmosphere. If the rich really think that this is their way out, it would be about the fastest way that they could make things much worse for everyone they leave behind. (Not that their end will likely be very pleasant.)

Laurent

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Re: Toward a complete list of climate feedbacks
« Reply #6 on: August 28, 2013, 09:23:56 AM »

Sigmetnow

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Re: Toward a complete list of climate feedbacks
« Reply #7 on: August 28, 2013, 05:27:32 PM »
Although I love the idea of space travel, I’m waiting for the big, bright ships with artificial gravity.  :)
But more than 165,000 people have applied to join the manned Martian colony effort envisioned by the non-profit Mars One Foundation.

“The organizers say the $6 billion cost for the first landing would be covered through reality-TV deals and merchandising, but they skirted pointed questions about the plan's financial feasibility.”

http://www.space.com/22498-mars-one-martian-colony-deadline.html
http://www.nbcnews.com/science/thousands-want-take-one-way-trip-mars-will-you-pay-6C9552007?franchiseSlug=sciencemain

wili

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Re: Toward a complete list of climate feedbacks
« Reply #8 on: August 28, 2013, 06:39:40 PM »
That seems utterly crazy but also utterly unsurprising.

I guess all this could fit under the fifth of my "positive feedback: human response" categories:

"--more and more people moving to avoid consequences of GW"

though I have to admit that when I penned this I had not been thinking about off-planet migration.

Artful Dodger

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Re: Toward a complete list of climate feedbacks
« Reply #9 on: August 29, 2013, 07:22:39 AM »
The topic of off-planet migration is quite popular in 'Cli-fi' these days.

Cheers!
Lodger

Anne

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Re: Toward a complete list of climate feedbacks
« Reply #10 on: September 11, 2013, 02:42:27 AM »
Here's a feedback I haven't come across before: jellyfish.
Our changing climate is also having many impacts on jellyfish. As the oceans warm, the tropical box jellyfish and the Irukandjis are likely to extend their ranges, while other species will benefit from the lowered oxygen levels that warmer waters contain. Remarkably, jellyfish may have the capacity to accelerate climate change. This can happen in two ways. Jellyfish release carbon-rich feces and mucus (...) that bacteria prefer to use for respiration. As Gershwin puts it, “jellyfish blooms turn these bacteria into carbon dioxide factories.” But jellyfish also consume vast numbers of copepods and other plankton. These creatures migrate vertically through the water column, taking in carbon-rich food at the surface and releasing it as fecal pellets, which fall to the sea floor and are buried. The plankton are thus a major means of taking carbon dioxide out of the atmosphere and oceans. If their loss occurs on a large enough scale, it will hasten climate change.

That snippet is just one aspect of this long and fascinating NYRB article on Lisa-ann Gershwin's Stung! On Jellyfish Blooms and the Future of the Ocean. It is well worth the time. The book charts the relentless march and proliferation of jellyfish following overfishing of its predators and competitors, and the ways it impacts on human life, and will not make for happy reading.

wili

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Re: Toward a complete list of climate feedbacks
« Reply #11 on: September 11, 2013, 06:13:16 PM »
Thanks, that's not one I had heard or thought of, either, though I knew, of course, that jellyfish were becoming predominant in more and more of the sea. I suspect that it is these biological feedbacks that will be the hardest to take account of in aggregate.

wili

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Re: Toward a complete list of climate feedbacks
« Reply #12 on: September 23, 2013, 06:51:02 AM »
Here's another one I didn't expect. Thx to prok at rc for the link:

Global Warming Amplified by reduced Sulfur Fluxes as a result of Ocean Acidification


Climate change and decreasing seawater pH (ocean acidification)1 have widely been considered as uncoupled consequences of the anthropogenic CO2 perturbation2, 3. Recently, experiments in seawater enclosures (mesocosms) showed that concentrations of dimethylsulphide (DMS), a biogenic sulphur compound, were markedly lower in a low-pH environment4. Marine DMS emissions are the largest natural source of atmospheric sulphur5 and changes in their strength have the potential to alter the Earth’s radiation budget6.
Here we establish observational-based relationships between pH changes and DMS concentrations to estimate changes in future DMS emissions with Earth system model7 climate simulations. Global DMS emissions decrease by about 18(±3)% in 2100 compared with pre-industrial times as a result of the combined effects of ocean acidification and climate change. The reduced DMS emissions induce a significant additional radiative forcing, of which 83% is attributed to the impact of ocean acidification, tantamount to an equilibrium temperature response between 0.23 and 0.48 K. Our results indicate that ocean acidification has the potential to exacerbate anthropogenic warming through a mechanism that is not considered at present in projections of future climate change.


http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1981.html

And on the importance of including "slow" as well as fast feedbacks in our models:

http://www.theguardian.com/environment/earth-insight/2013/sep/18/climate-change-double-impact-study
« Last Edit: September 23, 2013, 07:29:20 AM by wili »

prokaryotes

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Re: Toward a complete list of climate feedbacks
« Reply #13 on: September 24, 2013, 02:15:15 AM »
Re plant food

Plant Productivity Reduction with Climate Change
http://climatestate.com/2013/09/23/plant-productivity-reduction-with-climate-change/
ClimateState / Video Streaming & Research Magazine http://climateState.com

wili

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Re: Toward a complete list of climate feedbacks
« Reply #14 on: September 25, 2013, 03:49:25 AM »
Thanks again, prok. You de man.

Don't let the bastards (at rc and elsewhere) get you down.

ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #15 on: September 25, 2013, 08:23:25 AM »
The most obvious feedback not on your list is mankind. Since AGW is the result of human behavior, human behavior can change it and human behavior can change as quickly as the desire to do so.

The conditions to make an ice age cycle are also conditions to produce feedback. Feedbacks are not determined by direction. Large continental masses near the equator, disrupting ocean circulation towards the poles, large continental masses near the poles and oceans landlocked near the poles are the only conditions I know of that will cause the Earth to respond to the ice age cycle. The dynamics of sea ice within a basically landlocked ocean should not be expected to behave like sea ice surrounding a large continental mass near the pole. Why wouldn't a landlocked polar ocean with weakened sea ice respond by generating more sea ice once it reached a critical low? The arctic sea ice should respond to the same landlocked conditions based on it's yearly cycle. When ASI is weakened enough during cold sea ice forming times, it should respond by fragmenting, producing more sea ice and venting heat.

Now, I'm not saying the arctic sea ice can't be melted during summer times of glacial minimum or thermal maximums, because it has been, but we don't have a record of global temperatures accurate enough to show the process. I'm simply saying that arctic sea ice is a product of both winter and summer and it's yearly cycle isn't totally determined by a summer melt. I'm saying these recent summer melts can produce FYI weak enough during sea ice forming times to fragment forming more sea ice and vent heat from the ocean in a basically landlocked ocean near the poles.   

If you want to put that into a category, call it wishful or hopeful thinking! Call it prayers, who cares!

wili

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Re: Toward a complete list of climate feedbacks
« Reply #16 on: September 25, 2013, 11:59:25 AM »
"The most obvious feedback not on your list is mankind."

I realize there are a lot to scroll through so it's easy to see how you could have missed them, but at the end of both the 'positive' and the 'negative' feedback sections I actually do have fairly long lists of possible human responses that may serve as each kind of feedback. It would be great if you could look through them and see if there are any obvious ones that I missed (though that is a pretty open ended category).

As we have seen, the ice dynamics are endlessly complex in the Arctic. Your analysis seems reasonable, but I have a feeling there may be a number of other things going on. It's obviously an area of active discussion and research that I hope to keep somewhat abreast of from neven's forums and blog.

ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #17 on: September 26, 2013, 02:34:46 AM »
"The most obvious feedback not on your list is mankind."

I realize there are a lot to scroll through so it's easy to see how you could have missed them, but at the end of both the 'positive' and the 'negative' feedback sections I actually do have fairly long lists of possible human responses that may serve as each kind of feedback. It would be great if you could look through them and see if there are any obvious ones that I missed (though that is a pretty open ended category).

As we have seen, the ice dynamics are endlessly complex in the Arctic. Your analysis seems reasonable, but I have a feeling there may be a number of other things going on. It's obviously an area of active discussion and research that I hope to keep somewhat abreast of from neven's forums and blog.

wili, I don't need to scroll to read something on my computer monitor. The idea of my paragraph that contained more than the sentence you quoted is mankind has changed and can change the climate. The past human presence of converting forests to areas producing rice changed that climate. The deforestation in Europe and North America changed the climate. The summation of human desire can be as powerful as any physical climate feedback and the direction of that summation is as fickled as the direction of the wind.

I'm glad the 2013 arctic sea ice minimum didn't reach my estimate. Having the arctic sea ice exist is more important than having my vanity of being right about an estimate. Since I am free to have my personal concerns, I grant others similar freedom.

You asked for a complete list of climate feedbacks, so explain what were the feedbacks that produced those rapid changes of temperature based on ice cores and what were the feedbacks that changed ocean currents making a green Sahara! I'm not trying to be rhetorical, but let's think about it! There has to be some feedbacks working in those examples that we aren't aware of. Why wouldn't the main feedbacks like isolation and albedo changes control the times as expected and they don't? Granted, people who have studied it have some good analysis about aspects, but I don't consider it an explanation of the total, do you?

wili

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Re: Toward a complete list of climate feedbacks
« Reply #18 on: September 27, 2013, 12:26:33 AM »
"I'm glad the 2013 arctic sea ice minimum didn't reach my estimate. Having the arctic sea ice exist is more important than having my vanity of being right about an estimate."

Nicely put. Same here.

Notice that I said "toward" a complete list. I suspect we will never know all the feedbacks that have ever or will ever come into play. I hope to have some handle of over the major ones and some minor ones. I am not as knowledgeable about the formation of the Sahara as I'd like to be. If you have any useful links or insights, I'd love to look into it.

One thing I probably should have included is a clear definition of "feedback," specifically distinguishing it from "forcing." A forcing is what initially starts pushing something in a specific direction (in this case, the main forcing was human release of massive amounts of GHG, especially CO2 and CH4).

A ("positive") feedback is something that the forced system itself effects which then causes the system to go further or faster in the direction it was pushed by the initial forcing.

It sound so me as if perhaps you may be confusing the two terms, but I'm not sure I'm completely following your arguments. It's hard, for example, to see how the movement of continents could be a feedback, unless you know of some reason that climate change would accelerate (or slow) the rate of continental drift. When such drift affects ocean currents, that could (and has, iirc) push or 'force' climate in a certain direction. But that would make it a forcing rather than a feedback.

(Some things that started as forcings can, of course, become part of the feedbacks, like using more and more fossil fuels to power more and more ACs to keep people cool in a hotter and hotter world, but the essential concepts are distinct.)

I have a feeling that I'm missing your main point, though. Are you saying that because feedbacks have not lead to a hothouse earth at various points in the past, they therefore can't (or are not likely to) do so now or in the near future?

That would be a reasonable point, but I don't want to address if it is not the point you are trying to make.

ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #19 on: September 29, 2013, 04:46:04 PM »
"I'm glad the 2013 arctic sea ice minimum didn't reach my estimate. Having the arctic sea ice exist is more important than having my vanity of being right about an estimate."

Nicely put. Same here.

Notice that I said "toward" a complete list. I suspect we will never know all the feedbacks that have ever or will ever come into play. I hope to have some handle of over the major ones and some minor ones. I am not as knowledgeable about the formation of the Sahara as I'd like to be. If you have any useful links or insights, I'd love to look into it.

One thing I probably should have included is a clear definition of "feedback," specifically distinguishing it from "forcing." A forcing is what initially starts pushing something in a specific direction (in this case, the main forcing was human release of massive amounts of GHG, especially CO2 and CH4).

A ("positive") feedback is something that the forced system itself effects which then causes the system to go further or faster in the direction it was pushed by the initial forcing.

It sound so me as if perhaps you may be confusing the two terms, but I'm not sure I'm completely following your arguments. It's hard, for example, to see how the movement of continents could be a feedback, unless you know of some reason that climate change would accelerate (or slow) the rate of continental drift. When such drift affects ocean currents, that could (and has, iirc) push or 'force' climate in a certain direction. But that would make it a forcing rather than a feedback.

(Some things that started as forcings can, of course, become part of the feedbacks, like using more and more fossil fuels to power more and more ACs to keep people cool in a hotter and hotter world, but the essential concepts are distinct.)

I have a feeling that I'm missing your main point, though. Are you saying that because feedbacks have not lead to a hothouse earth at various points in the past, they therefore can't (or are not likely to) do so now or in the near future?

That would be a reasonable point, but I don't want to address if it is not the point you are trying to make.


If you view the world as an Ice Age world, then all types of radiative forcing are the same when converted to units that can be measured. The magnitude and direction changes in the ice age cycle, but the Physics doesn't. Consider a world that doesn't have mankind! Let's say a virus killed them all off tens of thousands of years ago. There is no industrial revolution and additions to the atmosphere, to the environment, or any contribution cause by man that we know of that can significantly affect the Earth. Can you explain why that world has to be better than our present world? Wouldn't the world be colder without mankind and why is that better?

The Earth obviously has cycles of solar insolation, but does it respond exactly to that change? Greenhouse gases also have cycles, including water vapor. Albedo changes also have their cycles. In terms of radiative forcing, these are the main drivers in our Ice Age world and I'd include changes in cloud formation and aerosols in my list of main drivers. Of those, some can be accurately measured and some can't. For example, we can accurately measure CO2 and methane in ancient atmospheres trapped in ice cores, but we can't measure water vapor. We can't accurately measure the contribution of man made aerosols and natural aerosols have always contributed to radiative forcing. We can estimate an albedo change and do so fairly accurately on land, if we have enough past data. Consider the complexities of estimating albedo changes in the North Atlantic Ocean! It's believed that sea ice extended all the way down to the Mediterranean Sea, between major glaciers. Scientists have speculated very large pieces of this North Atlantic sea ice would periodically break away causing global temperature fluctuations.

I gave you the three conditions to produce an Ice Age Earth and never mentioned continental drift. Two of those examples are present in our Earth today. The conditions involve disruptions of heat circulating to the poles. Continental drift was initially responsible for ending the Hothouse Earth and it followed this scenario. India collided with Asia causing decreases in atmospheric CO2. Antarctica separated from Australia and South America allowing the formation of a circumpolar current. An isolated Antarctica produced conditions for glaciation. At some point the cooling was enough to stop having a 22 degree C Hothouse Earth. The last major cooling event was North and South America connecting, disrupting a circum-equatorial current and isolating the Atlantic Ocean allowing it to cool. That allowed glaciation in Greenland and the Arctic Ocean to cool. Eventually other glaciers, mostly in the Northern Hemisphere joined in creating our present extreme shifts in global temperatures and approximately 100,000 year ice age cycles. To truly appreciate those events, you have to look at the time scales involved.

The information on the Green Sahara has been posted and it's just common encyclopedia information. It was mentioned because you were interested in feedbacks.

Geologic evidence from the beginning and end of the African Humid Period suggests that both the onset and termination of the African Humid Period were abrupt. In fact both events likely occurred on a timescale of decades to centuries. The onset and termination of the African Humid Period both occurred when the insolation cycle reached a value of roughly 4.2% higher than today. However, shifts in the insolation cycle are too gradual to cause abrupt climate transitions like those seen at the onset and termination of the African Humid Period all on their own. So to account for these rapid shifts in the climate of the Sahara, several nonlinear feedback mechanisms have been proposed. One of the most common sets of nonlinear feedback mechanisms considered, are vegetation-atmosphere interactions.[17] Computer models looking at vegetation-atmosphere interactions and insolation across North Africa have shown the ability to simulate the rapid transitions between "green Sahara" and "desert Sahara" regimes.[1] [18] Thus the results from these models suggest the possible existence of a vegetation-insolation threshold, which if reached, allows the Sahara region to rapidly transition from "green Sahara" to "desert Sahara" and vice versa.


Source: http://en.wikipedia.org/wiki/North_African_climate_cycles       


wili

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Re: Toward a complete list of climate feedbacks
« Reply #20 on: September 30, 2013, 08:12:47 PM »
I'm not sure it's worth continuing the conversation much further. If there were no humans, of course, there would be no one to make judgments about whether it was better or not. I'd just point out that humans have caused a sixth massive extinction events, so from the point of view of the rest of life, it could well be argued that it would have been a better world without us.

But I see no great benefit to discussing this further right now--a tall stack of freshman composition papers awaits my gentle attentions.  :) :( :'(

wili

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Re: Toward a complete list of climate feedbacks
« Reply #21 on: October 04, 2013, 06:26:11 PM »
Here's a particular aspect of water-vapor feedback that seems to be more important than previously supposed:

increased surface temperatures, such as from the addition of carbon dioxide to the atmosphere, leads to increased humidity in the stratosphere. Because stratospheric water vapor is a greenhouse gas, this leads to additional warming…

"We find that this stratospheric water vapor feedback is probably responsible for 5-10 percent of the total warming you get from adding carbon dioxide to the climate," Dessler explained. "While it's not really surprising that this process is going on, we were surprised at how important the process is for our climate system."

Climate models already include this process, but unevenly.


http://phys.org/news/2013-10-stratosphere-key-role-earth-climate.html

ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #22 on: October 04, 2013, 07:22:56 PM »
Here's a particular aspect of water-vapor feedback that seems to be more important than previously supposed:

increased surface temperatures, such as from the addition of carbon dioxide to the atmosphere, leads to increased humidity in the stratosphere. Because stratospheric water vapor is a greenhouse gas, this leads to additional warming…

"We find that this stratospheric water vapor feedback is probably responsible for 5-10 percent of the total warming you get from adding carbon dioxide to the climate," Dessler explained. "While it's not really surprising that this process is going on, we were surprised at how important the process is for our climate system."

Climate models already include this process, but unevenly.


http://phys.org/news/2013-10-stratosphere-key-role-earth-climate.html


Well, here is another thing that isn't worth continuing a conversation about!

When I think of increases in stratospheric water vapor, the first thing that comes to mind is methane and not carbon dioxide. Water is the most important greenhouse gas, but it has such an affinity for itself that it forms clouds in the troposphere. Methane and carbon dioxide doesn't behave that way and spreads more evenly throughout the atmosphere, so those greenhouse gases can easily get to the stratosphere. Methane breaks down to carbon dioxide and water.

I have no idea why that study talked about global warming and carbon dioxide while completely overlooking the role of methane increasing stratospheric water content. The IPCC and atmospheric scientists make that connection, so why didn't they? The process is well known.

wili

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Re: Toward a complete list of climate feedbacks
« Reply #23 on: October 05, 2013, 06:55:32 AM »
"Well, here is another thing that isn't worth continuing a conversation about!"

Yep, probably so. :)

I know about the methane thing, too. You know about it. We're just two @ssholes sitting around with our d!cks in our hands. So I have to assume that this study was, mmmm, maybe trying to point out something that every tomdickandhairy didn't already know? Like, mmm, maybe that's the whole point of doing, mmm, science?

Sorry about the sarcasm, but really?? Your main critique of the article is that it didn't tell you something you already knew??

I guess it's back to not continuing the conversation. 8)

ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #24 on: October 05, 2013, 11:10:16 AM »
@ssholes is spelled a$$holes. Free up one of your hands and get the Republicans to provide you their spellcheck!

On Earth, stratospheric water comes from methane. This isn't Uranus.

wili

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Re: Toward a complete list of climate feedbacks
« Reply #25 on: October 06, 2013, 06:20:03 AM »
LOL. Thanks for taking my off-color snark in the humorous vein it was intended.

ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #26 on: October 06, 2013, 08:35:12 AM »
LOL. Thanks for taking my off-color snark in the humorous vein it was intended.

Touche!

GeoffBeacon

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Re: Toward a complete list of climate feedbacks
« Reply #27 on: November 10, 2013, 01:43:53 PM »
Has this been mentioned on the ASF before?

 Previdi et. al. Climate sensitivity in the Anthropocene

http://onlinelibrary.wiley.com/doi/10.1002/qj.2165/full

wili

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Re: Toward a complete list of climate feedbacks
« Reply #28 on: November 10, 2013, 03:01:13 PM »
Thanks for reminding us of that one, Geoff. The take away quote from the abstract would seem to be:

The 2×CO2 Earth system sensitivity is higher than this, being ∼4–6°C if the ice sheet/vegetation albedo feedback is included in addition to the fast feedbacks, and higher still if climate–GHG feedbacks are also included.

It's not acceptable in scientific circles to claim a sensitivity of about 1 degree C from CO2 forcing, because, even though that's what it would be with no feedbacks at all, fast 'Charney' feedbacks from, for example, water vapor and a couple other factors, pushes it up to about 3 degrees for every doubling of CO2.

So why is it acceptable to constantly leave out these other feedbacks? Doesn't that just give a false sense of how dangerous a game we are playing? Is it because the uncertainties get higher the more of these you add? So why not just include the range of likeliest sensitivities once all known feedbacks are figured in?

ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #29 on: November 10, 2013, 05:44:49 PM »
The problem becomes calculating the Earth's sensitivity to climate change or more specifically what is the Earth's sensitivity now. I believe our adding CO2 changed all those feedbacks, which were slowly supporting negative temperatures to positive and any calculation of global temperature changes based on a single factor, such as increases or decreases of CO2, has to be lacking, if viewed without feedbacks. Delta CO2 seems quadratic or Gompertz when taken to equilibrium, but it's only my estimate based on limited data and something I can't prove. I believe climate sensitivity to CO2 is a function and not a constant number. 

I accept life one hazelnut at a time, with the sense to know Hansen doesn't know how sensitive our Earth is to CO2 and Robby the Robot's arms will guide my "Lost in Space." "Danger, danger, Will Robinson" doesn't cut it with someone who has already visited "Forbidden Planet" or tabloids of it's origin.

Do I really need to calculate climate sensitivity to CO2 to the nth degree, once I felt the snake crawling up my ass, trying to strike my neck and caught it in my left hand? Survivors don't look at their world that way and they don't place that snake on their enemies. Survivors respect life, including the life of that snake.

My Dr. Smith, lord (why didn't someone just smack the Queen upside her head) Monckton claims a very low value for the Earth's sensitivity to CO2. Consider that a minimum value based on someone who always starts off saying "I'm not a Scientist" and then being an aPolitician tries to act like one to his nth degree. Help us out, mighty Queen, because even the lowest peasant in all the lands deserves equal recognition compared to Mockhim. Letting loose the scoundrels from prisons and calling them lords is surely better than the status quo.

It's too bad Margaret Thatcher with her memory of chemistry isn't still around. Chemists believe in science and don't sell out like aPoliticians.

Maybe I'm just a dreamer, but I believe the largest missing climate feedback will be the people. I have the love and the hope and even the faith we can turn this world around.

wili

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Re: Toward a complete list of climate feedbacks
« Reply #30 on: November 10, 2013, 08:22:21 PM »
I'm not sure what that all was supposed to mean. But I'll just reiterate that a climate forcing of over 6 degrees C per doubling of CO2 should have different and even more pressing policy implications than a sensitivity of 3 degrees or less per doubling.

Or perhaps I should have said it should have had such policy implications years to decades ago, since things are now already so far gone, that we essentially need an international crash program essentially immediately.

http://www.ipsnews.net/2013/11/world-headed-for-a-high-speed-carbon-crash/

World Headed for a High-Speed Carbon Crash


https://www.youtube.com/watch?feature=player_embedded&v=KumLH9kOpOI

ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #31 on: November 10, 2013, 09:43:41 PM »
Can you provide evidence of even a global 1 degree C change, based on what is already done? Even a plus or minus 1 degree C global temperature change will drastically change our planet as we know it and is ill advised. Could mankind create the Hothouse +6 degree C Earth you envision? It's possible, if he burnt all fossil fuels and worked on carbonates to get that much CO2 into the atmosphere. It would be insane to do so and more insane to think mankind would do so. If it's so rational to compare our present Earth with the past, can anyone explain how the oceans had life with CO2 levels far above what we presently have? Our present Earth is positioned to have climate sensitivity to irradiance variability, but I doubt the old changes in solar irradiance affected it as much as today; it wasn't that sensitive then. It's the nature of life to not give up, until after it's last breath. Surely life can be destroyed, but when it comes to an alpha life type threatening it's family, I'll destroy it before it destroys me or mine. That's just the way life works.

I know adding CO2 to the atmosphere is a big problem, but I also know there are no immediate solutions. There could have been solutions developed in the past, but governments were too busy butting heads to smell the flowers. Thank God those days are gone!

My training has taught me in life, that a person doesn't even know what limits they can obtain, because who in their right mind would go there willingly. I still have faith in humanity and ultimately governments will bow down to them, even if knees need to be bent.

Our world isn't over, until it's over. Death doesn't come easy no matter how our mind prepared for it; our body just says no. 

wili

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Re: Toward a complete list of climate feedbacks
« Reply #32 on: November 11, 2013, 05:50:04 AM »
gge, again, I'm sorry, but I really find it hard to follow what you are trying to say.

You want evidence for a one degree celsius global change. Well, that hasn't happened yet (in our current warming) so it would be a bit hard to present evidence that it has. The figure is about .8 C rise since pre-industrial times, though, so we're getting close.

And note that I didn't "envision" a +6 degree C earth. I just said that that is the sensitivity implied by Hansen for a doubling of CO2 if you include all feedbacks.

Perhaps we could still avoid that now if we essentially stopped all further CO2 and methane emissions, though it certainly seems possible that the feedbacks that have already kicked in will be taking us up close to that number.

There is certainly no way at this point that we can avoid well over one full degree C rise above pre-industrial temps, and its almost certainly possible to avoid two degrees now either. Scientists have been warning TPTB about this now for decades, yet the only substantial response has been ever higher rates of carbon emissions.

 "It would be insane to do so and more insane to think mankind would do so"

So again, not sure really what you mean. Yes, insane for us to do so. But hardly insane to think that "mankind" would do so. We already have committed the earth to catastrophic warming and we continue to head down that highway to hell with ever more alacrity.

Again, the final part of your post leaves me even more baffled. You seem to be grasping at some kind of straws of a global revolution that will come in time to stop utter destruction. Do you see one scintilla of a hint of anything like that about to erupt in your own neighborhood or among your circle of friends and family? 'Cause I don't.

And after you say it's insane to think that humans would destroy the planet, you then admit that there are no solutions at a hand. But then you end by the rather cryptic statement that "the body just says no"! Whose body says no to what?

As for the past, it's been a very long time since we've had CO2 levels even this high, and they are going much much higher. We have assaulted the oceans from multiple directions, but the speed at which we are both heating and acidifying them is unprecedented in the history of the planet, iirc.

And of course the rate of change is most of what kills things. It's the difference between having a ball of iron slowly pressed against your cheek, giving you plenty of time to move away from it, and having the same hunk of iron fired out of a cannon at your head point blank. The only difference is speed of change.

ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #33 on: November 11, 2013, 09:39:20 PM »
I appreciate the work Hansen has done to alert us to global warming, but let's be specific!

Some of these numbers that get tossed around just don't make sense. I assume doubling CO2 means doubling pre-industrial levels of 280 ppm to 560 ppm and the +6 degree C increase is also +6 degrees C at equilibrium more than the pre-industrial temperature. Is that correct and when did Hansen make that prediction?

We are presently around 400 ppm CO2 and live on a planet that responds to orbital cycles where CO2 varies from around 180 ppm to 300 ppm, based on the best data I've found available. The planet became that way about two and a half million years ago, when it's thermohaline circulation changed following the connection of North and South America. The event allowed the Atlantic Ocean to cool and the planet started to respond to orbital forcing, first by minor swings of global temperatures over short periods, but later by major swings in temperatures over long periods of time. Prior to that our planet was cooling due to weathering loses of CO2 and Antarctica developing a circumpolar circulation that isolated it and allowed the first ice sheets to form.

When we look back in the history of our planet, there is no time with recent continental arrangements that had 400 or 560 ppm CO2 with a planet warming and not cooling. The confidence that 400 or 560 ppm CO2 in our atmosphere is going to drastically change our planet is as near to certain as one can get, but the timing is highly uncertain.

I only have respect for Hansen, because he stood up when others didn't, but I think his estimates are twice what will be. We'll both be dead long before it's proven and it doesn't make a difference, because even minor global temperature warming is a disaster to our planet. We need to put things on hold and even remove CO2 from our atmosphere.

Even "Bob the Builder" knows "yes we can."


wili

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Re: Toward a complete list of climate feedbacks
« Reply #34 on: November 12, 2013, 12:16:28 AM »
Some of these numbers that get tossed around just don't make sense. I assume doubling CO2 means doubling pre-industrial levels of 280 ppm to 560 ppm and the +6 degree C increase is also +6 degrees C at equilibrium more than the pre-industrial temperature. Is that correct and when did Hansen make that prediction?


Ummm, that was from the link posted above by GB:
http://onlinelibrary.wiley.com/doi/10.1002/qj.2165/full


Specifically, it is my interpretation of this line from that abstract, also posted above:

The 2×CO2 Earth system sensitivity is higher than this, being ∼4–6°C if the ice sheet/vegetation albedo feedback is included in addition to the fast feedbacks, and higher still if climate–GHG feedbacks are also included.


(My emphases.)

Higher than 4-6 to me implies higher than 6 degrees C for a doubling of CO2. So, yeah, 6+ degrees C above pre-industrial temps by the time we hit 560ppm.

We are in the process of blowing past 400. The rate of increase was about 1 ppm/year through the '80's, iirc. More recently it has been in the 2 ppm/year range, most recently touching 3ppm/y.

So our contributions to the problem are accelerating even as we start to feel some of the first effects (and hints at pale comparisons to what is to come).

Even if:
1) we level off at 3ppm increase for a while (instead of increasing the rate of increase as we have so far), and even if:

2)no serious carbon feedbacks kick in, and if

3)carbon sinks that have been absorbing half our carbon emissions continue to hold up...

Even if all those unlikely-to-happen scenarios actually happen, we would hit 560 in about 100 years.


But since:
1) the rate of increase is almost certain to continue increasing, and since
2) carbon feedbacks almost certainly will bestarting to kick in in the next few years (if they haven't already), and since
3) carbon sinks are likely to give out sooner or later (probably sooner) some of them turning from sinks to sources...

Since all these are the most likely outcome, we are more than likely to hit the 580 level in 20-40 years, imvho. Of course, that doesn't mean that we will hit or exceed 6 degrees above industrial levels by then, necessarily, since it takes a while for the equilibrium temperature to catch up with the forcing. But we will have irrevocably committed ourselves to that level of heating at some points, and many people and major research institutions think that will be around 2100 or in the succeeding few decades.

(I no longer hold out much hope for 'peak oil' saving our sorry @$$e$ in spite of ourselves. Even though conventional crude does seem to have peaked, nasty stuff like tar sands seems to be more than ready to take its place, and there's a he!! of a lot of it, and even more shale guck after we go through the tar gunk.)

Sorry if this ruined your day.



TeaPotty

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Re: Toward a complete list of climate feedbacks
« Reply #35 on: November 12, 2013, 01:00:41 AM »
I share your sentiments Wili.

I wish I could tell myself that this is just some probability arrived at by correlation, but that math is really adding up.

IMHO, no scientist has better expressed this than Kevin Anderson, commenting here on Joe Romm's optimism about "economic growth", and the weakness of our actions:


1)  Once we quantify the 2°C probabilities and carbon budgets underpinning our analysis (and provided there are no nearby microphones and it is not a public fora) seldom is there any serious disagreement with either our analysis nor the broad thrust of our conclusions. Consequently, it is not, as Joe Romm asserts, that others simply consider our “view of economics is … wrong”. Rather, that when in more open fora, many people, including NGOs, find it either uncomfortable or unproductive to challenge the doctrine that ‘growth is compatible with combatting climate change’. On the few occasions where disagreements with our conclusions do remain, they stem typically from: 1) a strong belief in the efficacy and very rapid diffusion of negative emission technologies; 2) a suite of abstract assumptions on early mitigation accompanied with a higher probability of exceeding 2°C (see below); or, 3) a nebulous framing of climate change and unquantified rates of mitigation.

However and in contrast, by far the most common view expressed privately, is that we have left it too late to meet our 2°C commitments without unacceptably high rates of decarbonisation (i.e. rates incompatible with conventional economic growth). This position is shared by many senior scientists and economists advising government.

2)Our conclusion that “… dangerous climate change can only be avoided if economic growth is exchanged, at least temporarily, for a period of planned austerity within Annex 1 nations” was premised on a series of highly specified and explicit assumptions. Pivotal amongst these were the estimates, by Stern, the UK’s Committee on Climate Change and others, that mitigation rates in excess of 3% and 4% p.a. are incompatible with economic growth (we are unaware of any IAM that, for a reasonable probability of 2°C, outputs a prolonged mitigation rate over 4% p.a. – and most are well below this). So for Romm to justify his statement that “the literature, as well as [his] own experience helping companies reduce carbon pollution for two decades” doesn’t support our conclusion, he must demonstrate, a) Stern et al are wrong in their judgment that mitigation rates above ~4% p.a. are incompatible with economic growth; b) our choice of 2°C probabilities and accompanying carbon budgets is inappropriate; or c) our estimates of the 2°C mitigation rates for Annex 1 nations is flawed.

If it is either b) or c), then Romm has to make a case as to which assumption underpinning our analysis he disagrees with. In this regard, I point Romm directly to our Royal Society paper Beyond Dangerous Climate Change for a detailed account of our assumptions. However, to simplify, if it is judged appropriate to accept both a 50:50 chance of 2°C and that non-Annex 1 nations peak their emissions in 2025, then just one of the CO2-only scenarios delivers a 2°C budget (C+5 in the paper). This scenario requires immediate reduction rates of over 8% p.a. from Annex 1 nations, with non-Annex 1 nations delivering similar reductions in their emissions from fossil fuels from 2025.

In many respects we agree with the broad thrust of Joe Romm’s views as expressed in his Introduction to climate economics: Why even strong climate action has such a low total cost. However, the rates of reduction he is referring to are still well below those necessary for the Annex 1 nations not to renege on their international commitments on 2°C. Consequently, we hold to our original conclusion, noting only that given fossil fuel CO2 emissions in 2013 are likely to be almost 3 billion tonnes higher than they when our analysis was published (online in 2010), the necessary mitigation rates will be more challenging still.


http://kevinanderson.info/blog/follow-up-to-articles-by-klein-romm-about-2c-and-economic-growth/

ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #36 on: November 12, 2013, 01:39:06 AM »
It doesn't ruin my day, but does Hansen claim his estimates are fact, like you do? What is the range of error Hansen considers?

Let's just consider the CO2 level to become Eemian conditions and the number isn't important! I think Hansen and I can agree that at a certain CO2 atmospheric level, the radiative forcing will match the Eemian conditions. I think we would both agree on an approximate estimate of time for those conditions to manifest themselves. I'm sure Hansen and I would both agree that not only does the world have to stop adding CO2 to the atmosphere, but it has to find ways to remove damage already done.

Does that mean the world will end tomorrow or in the near future? No, it means our worlds (Hansen's yours and mine) will end basically tomorrow in a blink of geological time. The concern isn't immediate for destruction and involves people using their minds that don't want to leave that kind of legacy for future generations. That means there is time to fix it. Doesn't Hansen suggest growing trees and many others suggest removing carbon by many other means? Can you explain what you said on the biochar thread?

wili

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Re: Toward a complete list of climate feedbacks
« Reply #37 on: November 12, 2013, 03:35:06 AM »
"What is the range of error Hansen considers?"

Range of error cuts both ways, and, from what I've seen, generally the direction for higher probability of error is not the one you are hoping for--there is a fat tale in the distribution of possible error toward the hot side.

"That means there is time to fix it."

We can't exactly "fix it."

First, it's not a machine with replaceable parts. It's a fragile blue planet with lots of fragile living ecosystems within it, most of which are badly damaged or worse. CO2 doesn't go away. (But even if we can't fix it, we certainly can break it even worse than we have already by UN-sequestering massive amounts of carbon to the tune of 10 billion tons a year and rising, as we are very busily doing.)

And, no, you can't sequester it all away reliably in soils (not that I'm against sequestering as much as we can--it's just not a silver bullet.) See further discussion on at:

http://www.realclimate.org/index.php/archives/2013/11/cows-carbon-and-the-anthropocene-commentary-on-savory-ted-video/

The maths just don't work out. And, as one of the commenters pointed out, there is no guarantee that the even the soils that you do manage to sequester some CO2 in won't become desert and lose it all again under the gentle ministration of catastrophic climate change.

Keep in mind that permafrost is right about at the point when it will start emitting more carbon than it takes in--it is about to turn from a net sink into a net source. Once we cross that line, it is highly unlikely that anything will be able to stop the loss of all the permafrost.

Permafrost holds about as much carbon in it as all the other soils on earth combined.

So, no. A necessarily small subset of all those soils is not likely to hold more than all the carbon in all the soils on earth.

And I'm afraid there no other reliable way to re-sequester carbon at anything remotely like the scale and speed now needed.

But, yes. Of course. No one can say exactly what the timing will be. Perhaps it will take centuries rather than decades to reach the 6 degree equilibrium (if that is where it stops).

But so far, we mostly get surprises that things are going along decades or even centuries faster than models were predicting just a few years ago--the melting of Arctic sea ice being exhibit A, in this case.

......
Thanks for the Kevin Anderson quote.
« Last Edit: November 12, 2013, 03:45:51 AM by wili »

ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #38 on: November 12, 2013, 04:40:05 AM »
Keep in mind I'm not here to debate matters and am only here to discuss science! Cherry picking something to support your worn out point of view isn't science. I think Hansen would have better sense than to confirm your claims, but that's just an estimate of the relative respect I have for both of you. You don't behave like a scientist and Hansen does. Hansen makes sense and you don't.

Has it ever occurred to your mind, we have been warmer than now? We have trapped atmospheres of those times and there is no record of massive greenhouse gas release, like CO2 and methane.

I don't think it's possible to make a +6 degree C Earth, based on present temperature or pre-industrial and I'll tell you why. If it ever reached that temperature, it would just keep going higher until a 22 degree C Earth existed, via feedback. That would take millions of years to reach equilibrium.

Maybe we should just get Hansen on site to speak for himself. 

wili

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Re: Toward a complete list of climate feedbacks
« Reply #39 on: November 12, 2013, 05:21:52 AM »
"I think Hansen would have better sense than to confirm your claims"

I would appreciate it if you would not assume that you and Hansen are intellectual buddies.

I have cited Hansen's own words and given what seems to me to be a reasonable interpretation of them based on my understanding of the English language and of the science. If you have an alternative interpretation that you think better represents Hansen's view, please explain either how I may have misinterpreted the passage I quoted, or bring up another passage that I have overlooked.

Just claiming that you know what Hansen really think is...well, let's just call it not very productive.

Note that I didn't claim that I thought a 6 degree world was stable. But can you support your claim that it would take "millions of years to reach equilibrium"? Or should we just take your word for it again, like we should take your word that you know exactly what Hansen thinks and that he agrees with you?

We don't need the man himself here (though you should feel free to invite him, if you wish). We have his words.

I've referred to those words. You haven't. That would not suggest to most people that your position is closer to his than is mine.

I am not presenting my interpretation as some kind of debating point. You asked, and I answered to the best of my ability and understanding.

I am more than happy to be corrected if you can please point out to me where exactly I have misinterpreted the passage quoted. If you can't there's really no use continuing the discussion. It's boring to talk with someone whose position is essentially "I'm right and you're wrong, and I know it because...well, I just know it, and I don't have to back it up with anything more than broad suppositions."

Ignoring what a scientist is actually saying while claiming to be the great champion of his good sense is not a very impressive stance to take.
« Last Edit: November 12, 2013, 05:47:37 AM by wili »

Anonymouse

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Re: Toward a complete list of climate feedbacks
« Reply #40 on: November 13, 2013, 06:57:11 AM »
GAH.  I don't even know where to start but I imagine y'all have had the same experience.  So I do visit various websites for entertainment and brain candy.  This one often has many people  who are self-aware, educated and progressive commenting on various subjects, but some of the comments on this particular article on this particular website on this particular subject (as usual) has highlighted the lack of knowledge in some segments of the commentariat.  To be fair, there are a goodly number of people who, as usual, try to stem the tide of ignorance. 

http://gawker.com/good-news-for-bored-people-climate-change-promises-non-1463073776

ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #41 on: November 13, 2013, 04:31:58 PM »
According to your link, my <b>:

Hansen et al. (2008) estimated an Earth system sensitivity including ice sheet and vegetation albedo feedbacks of about 6°C for doubled CO2. This is an average Earth system sensitivity for the range of climate states between glacial conditions and ice-free Earth, and thus it largely reflects the changes that occurred during the Pleistocene glacial cycles. For smaller ice sheet changes, the sensitivity would be somewhat less. In this case, a useful palaeo-analogue for the future could be the mid-Pliocene warm period (∼3 My BP), which, relative to present-day, featured similar atmospheric CO2 levels and considerably smaller changes in global ice volume compared to those which characterized the Pleistocene glacial cycles. Lunt et al. (2010) estimated an Earth system sensitivity for doubled CO2 of 4–4.5°C for the mid-Pliocene relative to pre-industrial times. Although clearly smaller than the 6°C sensitivity given by Hansen et al. (2008), this nevertheless represents a significant enhancement (by ∼30–50%) of the fast feedback sensitivity.


(d) Earth System Sensitivity additionally including Human Behaviour Feedbacks: In the most comprehensive type of climate sensitivity, changes in human activity (e.g. changes in fossil fuel burning, land use and land/ocean ecosystem management) in response to ongoing climate change are regarded as a feedback. (Note that human behaviour changes can be either a forcing or a feedback, since they can initiate Earth system change and also be a response to that change.)


Source: http://onlinelibrary.wiley.com/doi/10.1002/qj.2165/full

Which Earth would be more sensitive to warming, our present Earth or the mid-Pliocene Earth?

Obviously every doubling of CO2 can't produce a 6 degree C increase in global temperature.

wili

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Re: Toward a complete list of climate feedbacks
« Reply #42 on: November 13, 2013, 06:42:31 PM »
Thanks for pointing that out. Yes, that, presumably, is the reason that, instead of saying 6 degrees, they only say 4-6 degrees to cover the low end (which is still alarmingly high) that Lunt came up with. But again, that is based on adding just the two noted feedbacks--ice sheet and vegetation albedo, both relatively "fast" feedbacks. The more you add other feedbacks, such as carbon feedbacks, the higher you have to set the sensitivity level, which brings you back up near or beyond 6 degrees.

As to human feedbacks, that could go either way.

Increased use of air-conditioning--especially as having it becomes more and more a life and death issues for more and more of humanity--will likely drive ever more coal burning (till we can get all electric generation totally renewable, still a far off goal.)

The wars, which most studies suggest will increase in scope and intensity with increased GW, are pretty much guaranteed to be fought using fossil fuels both for ordinance and for transport of all sorts; and of course, a good number of wars will continue to be fought over those ff wells and mines, with inevitable consequences of many of those sources catching fire.

If droughts and heat waves, two of the most reliable and predictable consequences of GW, have a great chance of people global warming seriously, Inhofe, senator of Oklahoma, ground zero for the recent heat waves and the on-going drought, would be one of the world's leaders in combating GW.

Reality, however, is a bit more complex (and depressing) than what simple thought experiments would tend to suggest.


Meanwhile, I came across this:
On our current emissions path, CO2 levels in 2100 will hit levels last seen when the Earth was 29°F (16°C) hotter

The disinformers claim that projections of dangerous future warming from greenhouse gas emissions are based on computer models.  In fact, ClimateProgress readers know that the paleoclimate data is considerably more worrisome than the models (see Hansen: ‘Long-term’ climate sensitivity of 6°C for doubled CO2).  That’s mainly because the vast majority of the models largely ignore key amplifying carbon-cycle feedbacks, such as the methane emissions from melting tundra...

Science has just published an important review and analysis of “real world” paleoclimate data in “Lessons from Earth’s Past” (subs. req’d) by National Center for Atmospheric Research (NCAR) scientist Jeffrey Kiehl.  The NCAR release is here: “Earth’s hot past could be prologue to future climate.”  The study begins by noting:

    "Climate models are invaluable tools for understanding Earth’s climate system. But examination of the real world also provides insights into the role of greenhouse gases (carbon dioxide) in determining Earth’s climate. Not only can much be learned by looking at the observational evidence from Earth’s past, but such know ledge can provide context for future climate change.

    The atmospheric CO2 concentration currently is 390 parts per million by volume (ppmv), and continuing on a business-as-usual path of energy use based on fossil fuels will raise it to ˆ¼900 to 1100 ppmv by the end of this century (see the first figure) (1). When was the last time the atmosphere contained ˆ¼1000 ppmv of CO2? Recent reconstructions (2-4) of atmospheric CO2 concentrations through history indicate that it has been ˆ¼30 to 100 million years since this concentration existed in the atmosphere (the range in time is due to uncertainty in proxy values of CO2).

The data also reveal that the reduction of CO2 from this high level to the lower levels of the recent past took tens of millions of years. Through the burning of fossil fuels, the atmosphere will return to this concentration in a matter of a century. Thus, the rate of increase in atmospheric CO2 is unprecedented in Earth’s history."

...

"What was Earth’s climate like at the time of past elevated CO2?

Consider one example when CO2 was ˆ¼1000 ppmv at ˆ¼35 million years ago
(Ma) (2). Temperature data (5, 6) for this time period indicate that tropical to subtropical sea surface temperatures were in the range of 35° to 40°C (versus present-day temperatures of ˆ¼30°C) and that sea surface temperatures at polar latitudes in the South Pacific were 20° to 25°C (versus modern temperatures of ˆ¼5°C).

The paleogeography of this time was not radically different from present-day geography, so it is difficult to argue that this difference could explain these large differences in temperature. Also, solar physics findings show that the Sun was less luminous by ˆ¼0.4% at that time (7). Thus, an increase of CO2 from ˆ¼300 ppmv to 1000 ppmv warmed the tropics by 5° to 10°C and the polar regions by even more (i.e., 15° to 20°C).

What can we learn from Earth’s past concerning the climate’s sensitivity to greenhouse gas increases? Accounting for the increase in CO2 and the reduction in solar irradiance, the net radiative forcing””the change in the difference between the incoming and outgoing radiation energy-of the climate system at 30 to 40 Ma was 6.5 to 10 W mˆ’2 with an average of ˆ¼8 W mˆ’2. A similar magnitude of forcing existed for other past warm climate periods, such as the warm mid-Cretaceous of 100 Ma (8). Using the proxy temperature data and assuming, to first order, that latitudinal temperature can be fit with a cosine function in latitude (9), the global annual mean temperature at this time can be estimated to be ˆ¼31°C, versus 15°C during pre-industrial times (around 1750) (10).

 Thus, Earth was ˆ¼16°C warmer at 30 to 40 Ma.

The ratio of change in surface temperature to radiative forcing is called the climate feedback factor (11). The data for 30 to 40 Ma indicate that Earth’s climate feedback factor was ˆ¼2°C Wˆ’1 mˆ’2. Estimates (1, 11) of the climate feedback factor from climate model simulations for a doubling of CO2 from the present-day climate state are ˆ¼0.5 to 1°C Wˆ’1 mˆ’2. The conclusion from this analysis””resting on data for CO2 levels, paleotemperatures, and radiative transfer knowledge””is that Earth’s sensitivity to CO2 radiative forcing may be much greater than that obtained from climate models"
(My formatting and bolds, mostly)



ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #43 on: November 13, 2013, 08:35:52 PM »
I'd say global the temperature was around 5 degrees C at the coldest point of glaciation and rose about 8 degrees C at the thermal maximum. Atmospheric CO2 levels changed from 180 ppm to 280 ppm during that period. The time period allowed most feedbacks to play out, but not all. It takes millions of years to change ocean temperatures to reach equilibrium. Therefore:

During the Pliocene the earth climate system response shifted from a period of high frequency-low amplitude oscillation dominated by the 41,000 year period of Earth's obliquity to one of low frequency-high amplitude oscillation dominated by the 100,000 year period of the orbital eccentricity characteristic of the Pleistocene glacial-interglacial cycles.[6]


Source: http://en.wikipedia.org/wiki/Pliocene_climate



http://pubs.giss.nasa.gov/docs/2005/2005_Dowsett_etal.pdf

Hansen is just giving his best estimate and he could be too low just like Monckton. The difference is Hansen put some thought in his estimate and Monckton just made it up.

The whole thing is academic, because we don't want to go there and I doubt we will. BAU can work in the now with minor problems, but not for decades without major problems. It's easier to work on ways to stop emitting CO2 than it is to remove it from the atmosphere, but there is nothing wrong with doing both. Hansen suggested trees. Nations can cooperate in space, so they should be able to work together in many ways to fight a climate war and multiply their efforts.   

wili

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Re: Toward a complete list of climate feedbacks
« Reply #44 on: November 14, 2013, 01:06:50 AM »
"It takes millions of years to change ocean temperatures to reach equilibrium. "

Source?

Mentioning Monckton in the same breath as Hansen is an insult to the latter. Why even mention the fraud?

I'd like to think we were on the brink of international cooperation in seriously fighting a 'climate war,' but I see little evidence of it.

sidd

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Re: Toward a complete list of climate feedbacks
« Reply #45 on: November 14, 2013, 07:37:48 AM »
oceans equilibrate in few millennia ... thermally

ocean oscillations never equilibrate ... these are like tose asymptotically _non_ convergent functions ...

look at some of the isaac held simulations on his blog

ggelsrinc

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Re: Toward a complete list of climate feedbacks
« Reply #46 on: November 14, 2013, 12:50:37 PM »
"It takes millions of years to change ocean temperatures to reach equilibrium. "

Source?

Mentioning Monckton in the same breath as Hansen is an insult to the latter. Why even mention the fraud?

I'd like to think we were on the brink of international cooperation in seriously fighting a 'climate war,' but I see little evidence of it.

You were given a source. Equilibrium climate sensitivity does keep traveling down as the Atlantic Ocean, the main connection to the Arctic Ocean cools and changes salinity during a cooling period, cause by the reduction of CO2 and changes in thermohaline currents. The change in climate frequency and magnitude is evidence. There is absolutely no doubt that the world we live in today doesn't have the same sensitivity to CO2 as the mid-Pliocene world, because the physics can't change. I often get assaulted, because I don't jump on the Doomsday bandwagon parade as a cheerleader, but there is enough time to fix things. Fixing ASI by human intervention should be step number one, because it's dumb to lose such an easy battle allowing an assault on Greenland that could be prolonged. The world needs some governments with Arctic territorial interests to side on their side. What the hell is wrong with putting a moratorium, for like let's say 50 years, and spend your time as nations developing what you already have and taking care of your people? When you know you are going too fast, you slow down. So what if some industry suffers in the process, it's called capitalism. It's the price you pay to advance and not keep dinosaur industries.

Can someone explain to me in numbers why a doubling of atmospheric CO2 is exactly 6 degrees? Why was it 8 degrees during the last glaciation for an increase from 180 to 280 ppm CO2 and that isn't double? 180 doubled to 360 doubled to 720 doubled to 1440 is beyond the difference between a 5 degree C world and a 22 degree maxed out temperature world? Climate sensitivity would have to be a function over time with evidence from the past that events can cause warming faster than cooling. 

wili

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« Last Edit: November 14, 2013, 03:23:28 PM by wili »

sidd

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Re: Toward a complete list of climate feedbacks
« Reply #48 on: November 17, 2013, 05:20:53 AM »
re:changing climate change sensitivity


Phil. Trans. R. Soc. A 2013 371, 20120294

http://dx.doi.org/10.1098/rsta.2012.0294

Hansen et. al, Fig 7b is attached

but read the whole thing, free access, quite good.

sidd


wili

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Re: Toward a complete list of climate feedbacks
« Reply #49 on: November 17, 2013, 06:24:02 AM »
Thanks, sidd, for that link. I'm generally blind to the obvious, so bear with me.

The graph you copied seems intriguing, but I have to confess to not having much of a clue as to how to interpret it.
« Last Edit: November 17, 2013, 06:49:27 AM by wili »