Climate, stabilty and feedback

[billvon]

There may be an argument about how disastrous only 2C man- made temperature rise would be, but most certainly consider +3C a very bad thing.

Agreed.

Just releasing enough CO2 at current rate to make +3C increase will probably acidify oceans killing most life in them

It would certainly cause a significant increase in the extinction rate, on the order of hundreds of thousands of times the background rate. (New species will evolve to fill the niches left by extinct species, but that will take millennia.)

Thus I would consider even only +2C "bad thing" as the models have errors - risk too big to take.

Also agreed.

IMO only a vicious sadist, living in latitude north of Mason-Dixion line, would not want to try to avoid +3C.

Or someone ignorant of the effects - which most people are.

Certainly no need to speak of or worry about a Venus like state - all are dead long before that could happen.

As I have mentioned in the past, if that is true, and you no longer feel the need to speak of or worry about it - you'll be helping the cause of reducing the long term problem of AGW overall.

 

[iceaura]

I always advocate for the opposite of what greens want.

People who say that always in practice advocate for one thing and one thing only: less governmental presence (taxes, regulations) in rich people's corporate operations. They don't even know "what the greens want", usually - that would involve listening, with comprehension, to actual "greens".

 

[sculptor]

interhemispheric climate connectivity

for marine benthic isotope stages (MIS) 11c and 31, maximum summer temperatures and annual precipitation values are ~4° to 5°C and ~300 millimeters higher than those of MIS 1 and 5e. Climate simulations show that these extreme warm conditions are difficult to explain with greenhouse gas and astronomical forcing alone, implying the importance of amplifying feedbacks and far field influences. The timing of Arctic warming relative to West Antarctic Ice Sheet retreats implies strong interhemispheric climate connectivity.

start with a 4 degrees C rise for the arctic
plug in the equable climate model(The term ‘‘equable’’ typically refers to both the
weak equator-to-pole gradient and reduced seasonality)

results for 40 degrees north latitude?
30 degrees south?

 

[Billy T]

... if that is true, and you no longer feel the need to speak of or worry about it - you'll be helping the cause of reducing the long term problem of AGW overall.

No need for the "if." In post http://www.sciforums.com/showthread...and-feedback&p=3226902&viewfull=1#post3226902 I prooved I realized that transition to Venus like state, or not, was of no concern to man. There I also said my interest in CH4 had been greatly reduced, explained why, and proved that too with quote of another post of mine.

Please read that post and if you don't want to comment, at least take into consideration what are my two main concerns for months. - I. e. stop beating the long dead horses but address them.

 

[brucep]

Agreed.

It would certainly cause a significant increase in the extinction rate, on the order of hundreds of thousands of times the background rate. (New species will evolve to fill the niches left by extinct species, but that will take millennia.)


Also agreed.


Or someone ignorant of the effects - which most people are.


As I have mentioned in the past, if that is true, and you no longer feel the need to speak of or worry about it - you'll be helping the cause of reducing the long term problem of AGW overall.

Read the Colin Goldblatt paper Billy T linked in his response to your thread originating post. Goldblatt analysis concludes, based on what's known, the 'runaway' can't happen on the planet earth. He also concludes that so much is unknown about the possibility of changing feed backs, over time, the prediction doesn't have much scientific value. Your last comment to Billy T is pretentious bullshit. You've fashioned yourself as an expert on this science when you're clearly not. Anybody who is familiar with the importance of Max Plancks work would know 'infinite temperature' doesn't apply.

 

[billvon]

Your last comment to Billy T is pretentious bullshit.

Sorry you can't have a rational discussion on the topic. Have a good day.

 

[billvon]

I prooved I realized that transition to Venus like state, or not, was of no concern to man. There I also said my interest in CH4 had been greatly reduced, explained why, and proved that too with quote of another post of mine.

Great; like I said, I think that will go a long way.

>at least take into consideration what are my two main concerns for months.

I think high altitude aerosols have the potential to both warm and cool the planet, like most cloud effects. Previous examples of high altitude cloud creation via meteor impacts and volcanism have tended to cause cooling, which argues against that being a "runaway" mechanism.

 

[Billy T]

... I think high altitude aerosols have the potential to both warm and cool the planet, like most cloud effects. Previous examples of high altitude cloud creation via meteor impacts and volcanism have tended to cause cooling, which argues against that being argues against that being a "runaway" mechanism.

That is true, except for the false conclusion which does NOT apply to carbon soot. Again, like in your OP, you prove that a little knowledge is dangerous as you ignore the fact that most aerosols scatter solar radiation instead of absorb it as soot always does. Because very many scatterings are required to "random walk" the photon back towards space there only needs to be a very tiny fraction of soot in the cloud to make nearly a black body absorber. I.e. many small angle scattering return the radiation to space - just like a high altitude, soot-free, cloud does.

Perhaps the most important type of anthropogenic aerosol in radiative forcing is sulfate aerosol. It is produced from sulfur dioxide (SO2) emissions associated with the burning of coal and oil. Since the late 1980s, global emissions of SO2 have decreased from about 73 million tons to about 54 million tons of sulfur per year. {Billy T inserts: this reduction has contributed to GW. Also note that volcanoes emit great masses of SO2 and SO3 plus some CO2; but the sulfates completely overwhelm the warming effect of the CO2 released.}

Nitrate aerosol is not as important as sulfate aerosol, but it has the potential to become a significant source of negative forcing. {I. e. cooling effect} One major source of nitrate aerosol is smog (the combination of ozone with oxides of nitrogen in the lower atmosphere) released from the incomplete burning of fuel in internal-combustion engines. ...

Both sulfate and nitrate aerosols act primarily by reflecting incoming solar radiation, thereby reducing the amount of sunlight reaching the surface. Most aerosols, unlike greenhouse gases, impart a cooling rather than warming influence on Earth’s surface. One prominent exception is carbonaceous aerosols such as carbon black or soot, which are produced by the burning of fossil fuels and biomass. Carbon black tends to absorb rather than reflect incident solar radiation, and so it has a warming impact ...

Natural forms of aerosol include windblown mineral dust generated in arid and semiarid regions and sea salt produced by the action of waves breaking in the ocean.

I note that fine salt crystals and sand dust (unless from relatively rare black volcanic sand) are also scatters, not absorbers. For example, you can get sunburned sitting on beach on sunny day even if never leaving the protection of beach umbrella if you also don't use any sun-screen cream.

 

[billvon]

That is true, except for the false conclusion which does NOT apply to carbon soot.

But it certainly does apply to high altitude aerosols, including sulfur. So if you are lofting high altitude aerosols that include sulfur (which forests do indeed include) you get sulfuric aerosols which persist far longer than soot does, since soot is a particulate.

So which will dominate? The short term warming effects of the soot, or the longer term cooling effects of the sulfur? That's a good question, one that (hopefully) will be answered by research.

 

[Billy T]

But it certainly does apply to high altitude aerosols, including sulfur. So if you are lofting high altitude aerosols that include sulfur (which forests do indeed include) you get sulfuric aerosols which persist far longer than soot does, since soot is a particulate.

So which will dominate? The short term warming effects of the soot, or the longer term cooling effects of the sulfur? That's a good question, one that (hopefully) will be answered by research.

But your "if" is not the case and the sulphates molecules are highly water soluble so rain out - you've heard of "acid rain" I'm sure.

Wood biomass has a very low sulphur content compared to that of coal, oil and peat.
The sulphur content in stem wood is about 0.01 percent, in bark 0.02-0.1 percent, and in needles 0.04-0.2 percent of dry mass. In practice, when burning wood, the total amount of SO2 emissions is very small or unsubstantial.
Therefore the combustion of wood does not require any specific sulphur discharging equipment.

"Dry (moisture-free) wood is about 48-50% carbon, 38-42% oxygen, 6-7% hydrogen and a number of other elements, such as nitrogen and sulfur in very small percentages. These percentages are based on the weight of the elements as a percentage of dry wood mass.

SUMMARY: The Carbon to Sulphur ratio of wood is about 5,000 to 1 (or greater).

I'm not a chemist, but think the SO2 dissolves in H2O to make H2SO3, which some how transforms into weak sulpheric acid (H2SO4) The less common SO3 goes to sulpheric acid directly when dissolved in a cloud's water drop. I'm pretty sure that SO3 is less common in wood fire smoke than SO2, but if the fire becomes a "fire-storm" as large one might with hurricane wind speeds sucking in lots of O2, the combustion may go all the way to SO3, the lower energy state.

 

[billvon]

But your "if" is not the case and the sulphates molecules are highly water soluble so rain out

Are you suggesting that stratospheric sulfur-containing aerosols will be "rained out?"

 

[Billy T]

Are you suggesting that stratospheric sulfur-containing aerosols will be "rained out?"

I think so. I recall reading that the typical H2O molecule does so in a week or ten days. High up it may be in a growing ice crystal that falls faster than fine soot; but even if the soot falls out 100 times faster, it start with the 5000 to 1 advantage, so I bet even a month later it dominates, but don't know if anyone has researched this question.

Also, I don't know Guy McPherson's source but he says that if civilization collapses quickly that the temperature will rise nearly 2C in a week as that collapse terminates the constant injection of sulfate aerosols, mainly due to coal burning, that are now helping hold the temperature down.* In general he does have good documentation for his claims, but may "cheery pick" when there is some range of values in the literature.

* A corollary to this is that the EPA forcing power plants to switch from coal to natural gas may be exactly the wrong thing to do. - Would not be the first time the government has required exactly the wrong thing be done.

 

[billvon]

I think so. I recall reading that the typical H2O molecule does so in a week or ten days. High up it may be in a growing ice crystal that falls faster than fine soot. even if the soot falls out 100 times faster it start with the 5000 to 1 advantage, so I bet even a month later it dominates, but don't know if anyone has researched this question.

Hmm. Given the scarcity of rain/ice in the stratosphere, I don't think that would happen very quickly. After the eruption of Mt. Pinatubo, high altitude sulfuric aerosols remained in the atmosphere, causing measurable cooling, for three years.

 

[Trippy]

I think so. I recall reading that the typical H2O molecule does so in a week or ten days. High up it may be in a growing ice crystal that falls faster than fine soot; but even if the soot falls out 100 times faster, it start with the 5000 to 1 advantage, so I bet even a month later it dominates, but don't know if anyone has researched this question.

That may be true of Tropospheric water vapour.

The e-folding time for sulfur-dioxide -> Sulfuric acid in the stratosphere is on the order of one month. Here (I hope) is a paper discussing the life cycle of stratospheric aerosols.

 

[Billy T]

... The e-folding time for sulfur-dioxide -> Sulfuric acid in the stratosphere is on the order of one month. Here (I hope) is a paper discussing the life cycle of stratospheric aerosols.

thanks for the link. I'm not surprised by a month to form tiny weak H2SO4 drops in the stratosphere. Not much SO2 up there and if I understood on quick skim it was convected up there from lower layers. What did surprise me was how un-important gravity is in even the stratosphere:
"we can get an idea of the residence time of the aerosol particles by assuming the size distribution of Fig. 7 and evaluating the fall velocity for conditions equivalent to 22-km altitude and 220-K temperature. We obtain fall speeds of the order of 1.0 ´ 10-3 cm s-1 for particles of radius 0.06 mm and of the order of 5.0 ´ 10-3 cm s-1 for particles of radius 0.25 mm. At these rates, it would require 6.3 yr and 1.3 yr, respectively, for these particles to fall 2 km to an altitude of 20 km. Thus the sedimentation of aerosol particles is not an effective removal mechanism, except for the very few particles that somehow survive long enough in the stratosphere to grow to large sizes (i.e., an appreciable fraction of a micron in radius)."

I knew that gravity did little in the lower layers to change the molecular mix of the air (but of course makes warm air masses rise) but believed it was why H2 molecules were more lost to space than O2. Its effect must be still higher.

Both the following, I think, may be in part at least what I have been calling the "Hadley cell" transport. - is that correct?
"we assume that air rises in the Tropics, moves out of the Tropics, and descends into the extratropical lower stratosphere (the lowermost stratosphere). This is, of course, essentially the Brewer–Dobson circulation described by Brewer (1949) and Dobson (1956). Once the air has descended into this region of the stratosphere, it can be transported isentropically into the troposphere. Aerosol particles are, of course, carried along with these air masses. As soon as the particles reach the troposphere they are lost, primarily by scavenging in clouds."
AND
"The aerosol is eventually transported to midlatitudes, crossing the boundaries of the “leaky tropical pipe” (Plumb 1996) in the 15°–30° latitude range. " and in Figure 1, the north going arrow called the "Tropical Pipe." If yes - why has Hadley lost the credit?

They make frequent reference to "isoentropic" I assume that is saying that turbulent dissipation is not important. - Is that correct?

It is a good paper, but I doubt I will study it much. Point me to any section you think contradicts or lessens my concern that large tropical fire may make big global warming impact, both by the large CO2 "burp" * and by very significant lowering of the albedo of high clouds and warmed soot in them evaporating water drops it collided with - a "double whammie" as increased local H2O vapor from the drop is strong IR escape blocker while the clean water drop (at least reduced in size if not all gone) helped keep the cloud's albedo high.

* I forget but seem to recall that burning all the Amazon would make a few years worth of man's release of CO2 but I still fear a tiny fraction of very small black soot added to the now clean very high cloud (even the ice crystals) is an even greater GW stress. - might send significant part of the tropics into local thermal run-a-way, as section of SW Pacific Oceans already is. That could become self-sustaining even if the soot slowly was taken back down as the evaporation increase may feed on its self - as seems to be the cause for the enduring Pacific Hot Spot's local thermal run-a-away NASA's Ames center is studying.

I'm sure you know but for others: "local thermal run-a-away" just means that in some local region, more solar heating than IR energy removal is happening. The excess is mainly convected away to keep it (we hope) from becoming an expanding run-a-way region.

 

[billvon]

Point me to any section you think contradicts or lessens my concern that large tropical fire may make big global warming impact, both by the large CO2 "burp" * and by very significant lowering of the albedo of high clouds and warmed soot in them evaporating water drops it collieds with - a "double whammie" as increased local H2O vapor from the drop is strong IR escape blocker while the clean water drop (at least reduced in size if not all gone) helped keep the cloud's albedo high.

The SCAR-B experiment (in Brazil) does indeed seem to contradict the idea that tropical fires will cause warming; indeed, the study indicates that it generates a net cooling effect.

============
The Smoke, Clouds, and Radiation-Brazil (SCAR-B) field project took place in the Brazilian Amazon and cerrado regions in August-September 1995 as a collaboration between Brazilian and American scientists. SCAR-B, an experiment to study biomass burning, emphasized measurements of surface biomass, fires, smoke aerosol and trace gases, clouds, and radiation, their climatic effects, and remote
sensing from aircraft and satellites.. . . Radiative forcing: estimates of the globally averaged direct radiative forcing due to smoke worldwide, based on the properties of smoke measures in SCAR-B ( -0.1 to -0.3 W m-2.)
============
(search for the document jgrd6136.pdf; I have the doc but can't find the link.)

The IPCC notes that in general this is supported by multiple studies. The one exception they found was in areas near snow-covered mountains (like the Himalayas) - in such cases the effect of albedo change on snow overwhelmed the negative forcing, and had a net positive forcing.

 

[Billy T]

The SCAR-B experiment (in Brazil) does indeed seem to contradict the idea that tropical fires will cause warming; indeed, the study indicates that it generates a net cooling effect. ...

Thanks. Google search on SCAR-B Brazil turns up many hits. The only one I have read yet is: ftp://ftp.lalinet.org/Publications_...apportionment in Amazonia Artaxo JGR 1998.pdf and it is quite informative, but I don't think of much use for evaluation of my concern about soot pumped high up to darken highly reflective clouds for two reasons.
(1) Airplanes used could not go above "4 to 5 Km"
(2) There were only many relatively small and widely separated "fires of opportunity" that happen in Brazil annually in the dryer months and at least half the long flights collecting samples were not even over the Amazon rain forest.* The natural winds dispersed the aerosols and only about 1/3 of those collected were related from combustion of organic materials. The problem I am concerned about is a huge fire - with it generating fire storm winds rapidly injecting the carbon black and other aerosols high much higher up.

* See figure 1, which will not copy for me to post, show the flight paths, which were typically 3 or more hours long and rarely in obvious smoke. I need to quit now - will look at some of the other hits tomorrow.

 

[Trippy]

thanks for the link.

You're welcome.

I'm not surprised by a month to form tiny weak H2SO4 drops in the stratosphere. Not much SO2 up there and if I understood on quick skim it was convected up there from lower layers. What did surprise me was how un-important gravity is in even the stratosphere...

I knew that gravity did little in the lower layers to change the molecular mix of the air (but of course makes warm air masses rise) but believed it was why H2 molecules were more lost to space than O2. Its effect must be still higher.

What effect? Gravity?

Both the following, I think, may be in part at least what I have been calling the "Hadley cell" transport. - is that correct?

No.

"we assume that air rises in the Tropics, moves out of the Tropics, and descends into the extratropical lower stratosphere (the lowermost stratosphere). This is, of course, essentially the Brewer–Dobson circulation described by Brewer (1949) and Dobson (1956). Once the air has descended into this region of the stratosphere, it can be transported isentropically into the troposphere. Aerosol particles are, of course, carried along with these air masses. As soon as the particles reach the troposphere they are lost, primarily by scavenging in clouds."
AND
"The aerosol is eventually transported to midlatitudes, crossing the boundaries of the “leaky tropical pipe” (Plumb 1996) in the 15°–30° latitude range. " and in Figure 1, the north going arrow called the "Tropical Pipe." If yes - why has Hadley lost the credit?

Brewer-Dobson circulation is a model of stratospheric circulation (remember, the paper is dealing with stratospheric aerosols), Hadley's cells are a model of Tropospheric circulation. They're two different phenomena.

They make frequent reference to "isoentropic" I assume that is saying that turbulent dissipation is not important. - Is that correct?

No, not quite. Isentropic processes are processes where entropy remains constant. So in weather, for example, there are processes that are isentropic, for example isentropic lifting. Isentropic analyses of weather systems can reveal more information than straight isobaric alone might. And then there's Isentropic potential vorticity. Following isentropic surfaces is one way that air from the stratosphere can be mixed with air from the troposphere - an air-mass moving isentropicly from a high latitude to the equator will cross the tropopause at some point.

It is a good paper, but I doubt I will study it much. Point me to any section you think contradicts or lessens my concern that large tropical fire may make big global warming impact, both by the large CO2 "burp" * and by very significant lowering of the albedo of high clouds and warmed soot in them evaporating water drops it collided with - a "double whammie" as increased local H2O vapor from the drop is strong IR escape blocker while the clean water drop (at least reduced in size if not all gone) helped keep the cloud's albedo high.

There were two reasons I posted the link to that paper.
1: It illustrates that the lifetime of sulfate aerosols in the stratosphere is substantially longer than you were assuming.
2: It demonstrates that in any treatment such as you're proposing you need to consider stratospheric dynamics as well as tropospheric dynamics (everything you've focused on so far has been tropospheric rather than stratospheric dynamics, with the possible exception of methane).

* I forget but seem to recall that burning all the Amazon would make a few years worth of man's release of CO2 but I still fear a tiny fraction of very small black soot added to the now clean very high cloud (even the ice crystals) is an even greater GW stress. - might send significant part of the tropics into local thermal run-a-way, as section of SW Pacific Oceans already is. That could become self-sustaining even if the soot slowly was taken back down as the evaporation increase may feed on its self - as seems to be the cause for the enduring Pacific Hot Spot's local thermal run-a-away NASA's Ames center is studying.

Did you ever look into any of that stuff from Hadly CRU that I posted earlier? The stuff about the conference?

 

[sculptor]

Brewer-Dobson circulation is a model of stratospheric circulation (remember, the paper is dealing with stratospheric aerosols), Hadley's cells are a model of Tropospheric circulation. They're two different phenomena.

Then we plug in rossby waves and orographic gravity wave drag and the picture gets a tad more complex?

 

[sculptor]

oops double post

this seems to be happening a lot more lately