OT: How to profit from AGW?

There was a session on this at the recent AGU meeting. It appears that there is more evidence than the one paper.

So I think my original point that contrails are a non CO2 source of the A in AGW appears valid.

/quote

Dr. David W Fahey, of NOAA?s Earth Systems Research Laboratory, introduced the session by highlighting the holes remaining in our understanding of contrail?s climate impact. Airplane engine emissions and combustion products react with the local atmosphere, causing changes to the local atmosphere?s radiative forcing. These contrails last between six and eight hours before dissipating into clouds.

In 2005, aviation represented 3.5 percent of anthropogenic radiative forcing, up to 4.9 percent if you include cloudiness caused by the contrails. Future contrail impacts could be two to three times higher by 2050, a 20 percent increase per decade.

Global models show that contrails can create up to 10 percent of total cloud cover in Europe, comparable to natural cirrus cloud coverage, says Ulrike Burkhardt, from the DLR Institute for Atmospheric Physics in Germany. Natural coverage reacts to the extra humidity by reducing their radiative forcing up to two percent in these high traffic areas.

Preliminary model data from Marc Jacobson of Stanford University indicates a temperature increase between .03 and .06 K in the next decade due airplane emissions. This means that aircraft emissions could be responsible for up to 8 percent of surface warming and 14-20 percent of Arctic warming each decade.

/end quote

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Perhaps, but I've not got much faith in your eyeball, and teh general figure for the arctic is more than twice that. The point is that the Greenland ice-cap is right in the middle of one of the positive feedbacks - changing snow cover in the norther hemisphere - which alows the Milankovitch effect to produce ice ages and interglacials, and it is at one of the ends of the thermohaline circulation (locally manifested as the Gulf Stream) so that any variation in the heat transported through the oceans shows up as a temperature change on the Greenland ice-cap.

It is not a represnetative sample of the globe as a whole, and large fluctuations there don't "prove" that the global climate as a whole naturally moes around anything like as much.

It worked fine last night and the administroator claims to be working to get it back up.

As usual, you are indulging in selective quotation

/quote

In the two upper zones, the increase in the inferred temperatures might reveal recent changes that are due to non-natural forces. Although sediments were less compact near the water/sediment interface and this higher water content could have prevented a good relationship between sedimentology and chironomid-inferred temperatures, our results revealed that both variables are generally close but the relationship between both variables is not as high as the one observed during the MWP. Similar results were observed in Europe with inferred summerMWPtemperatures thatwere the same as those measured into the last quarter of the 20th century (Goosse et al.,

2006). The record from Southampton Island does not reveal such highamplitude climate changes as observed elsewhere in the Canadian High Arctic, but undoubtedly this island is actually experiencing environmental changes.

/end quote

In fact the paper supports my point that the arctic environemnt shows an erratic response to global climate change.

So what? The methane clathrates won't go unstable until the climate warms up more than the peak of last interglacial, which was higher than anything we've seen in thsi interglacial.

It's not exactly interesting to observe that this current interglacial peaked some 8,000 years ago, and that temperatures were slowly declining until we started burning a lot of fossil carbon. Ruddiman thinks we started in on anthropogenic global warming a couple of thousand years ago - agriculture generates extra methane - but his ideas are controversial.

-- Bill Sloman, Nijmegen

Go from the roughly 1878 peak to the roughly 2005 peak, and the increase in HadCRUT-3 is .6 degree C.

And I suspect back in 1878, we were only almost done warming up from the LIA. Looks to me now .5-.55 degree C of actual non-periodic warming. Make that .45-.5 degree C if it turns out they insufficiently filtered for growth of urban contamination of surface stations.

Whether the truth is .5 or .6 degree C of AGW so far, .76 is not all AGW.

No, AMO being high has heat shifted to the north. The world is warmer then - apparently to me, from melting of Arctic sea ice and northern snow cover, where surface albedo positive feedback is strong. The southern hemisphere has much less land with variability in snow cover, and Antarctic sea ice is looking more stable than Arctic sea ice - so surface albedo positive feedback is mostly a northern thing.

It's also a 1-year event, nowadays not looking like it has a large effect on reported 1979-onward warming rates.

Meanwhile, AMO is good for .3-.32, possibly .35 degree C peak-to-peak, and was mostly in upswing during the time since MSU satellites were put to use to monitor lower troposphere temperature.

Solubility of a gas in a liquid is actually a ratio of partial pressure of the gas to concentration in the liquid.

Suppose we manage 4 degrees C of warming of the oceans with CO2 increased to 500 PPMV from the 385 PPMV of now or very recently:

With CO2 partial pressure at 760 Torr, solubility of CO2 in water is 2.1 grams/kg at 15 degrees C (reasonably close to current worldwide average liquid surface temperature if I did not screw up),

and 1.75 grams/kg at 19 degrees C.

So that 4 degree C warming reduces solubility of CO2 in water to 83.3% of what it was.

But if atmospheric CO2 is increased to 500 PPMV from 385 PPMV, multiplying .833 by 500/385 means 1.08 times as much CO2 in the water as we have now. Even if we get that much warming with that little additional CO2 added to the atmosphere, the ocean will still be removing some of it rather than returning any to the atmosphere.

- Don Klipstein ( snipped-for-privacy@misty.com)

Interesting!

However, I have a lot of experience looking at the sky. My day job is largely an outdoor one, and I have been very interested in weather and what goes on in the atmosphere for decades.

My experience in/near Philadelphia (where air traffic is heavy) suggests to me that the mentioned extent of existence of contrails is exaggerated. I don't see contrails existing even within an order of magnitude as much as natural cirrus clouds do. I occaisionally see spectacular contrail presence like that in the photo in the link or even slightly greater, causing significant high cloud cover, but only for a few hours a few times a year.

- Don Klipstein ( snipped-for-privacy@misty.com)

Multidecadal

Except that Little Ice Age seems to have been more of a Northern Atlantic phenomena than a global experience - temperature proxies from other areas show aimilar sorts of excursions, but they aren't synchronous with the proxies from around the North Atlantic. Presumably the thermo-haline circulation was delivering less warm water to the northern parts of the Atlantic Ocean during the Little Ice Age, but more someplace else.

This doesn't really work You think that you can see some trace of a natural long term cycle that accounts for part of the warming over the last century; not the Altalantic Multidecadal Oscillation since we have 130 years of observations, which is two complete 65 year cycles, but something longer term for which we don't have a long enough string of observations to say anything meaningful about

This sort of fits; the satellite records show around 0.18 degree C per decade;

you are claiming about 0.1 degree C for the AMO and the 0.76 degrees C over a century is close enough to 0.08 degrees C per decade

Henry's Law

's_law#Temperature_dependence_of_the_Henry_constant

The Wikipedia article on Henry's Law gives a formula and a single constant for CO2 (amongst other gases) although it does point out that tabulated experimental data is to be preferred.

True, but as the water gets warmer, the proportion absorbed keeps on going down. A proper nerd enthusiast would take the CO2 forcing figures and the temperature-dependent solubility and find out where the cross-over to emission could be expected to happen.

In fact, a lot of the CO2 capture and storage in the oceans is biological. More CO2 makes for a more acid ocean, and diatoms that form carbonate shells apparently won't be able to do it if the ocean gets too acid.

Nutrients also play a part

and Henry's Law may not be decisive.

-- Bill Sloman, Nijmegen

It appears to me that LIA was for real.

- Don Klipstein ( snipped-for-privacy@misty.com)

In , Bill Sloman wrote in part:

I read that every few months, and the numbers for degrees/decade - especially RSS - recently took big jumps that did not make sense to me.

Meanwhile, the decadal trend for UAH from its beginning through November

2009 was .13 degree/decade.

It will be updated with the December figure very soon, fair chance Tuesday 1/5/2010.

RSS says .153 degree/decade for 1979 through 2008.

They say .153 degree/decade as of November 2009:

I am claiming that from the 1878 peak of AMO to the recent one, HadCRUT-3 warmed .6 degree, and .76 degree is not all from AGW. Since CO2 was still pretty close to 280 PPMV in 1878, there was no significant warming prior to then from anthropogenic CO2.

- Don Klipstein ( snipped-for-privacy@misty.com)

l Slomanwrote in part:

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So ask Robert A. Rhode to explain it. He's a graduate student working on a Ph.D, in the area, and probably has a prepared explanation of exactly what is going on.

Basically, we haven't yet collected enough data to nail down exactly what is going on at the moment. The ice core data does give us a reasonable handle on how the sums come out for CO2 levels from about

180ppm to 280 ppm, and the 0.7C rise from 280 ppm to about 380 ppm fits with that.

It may be that the ocean currents are messing up our current measurements and making the global temperature look more sensitive to

+280 ppm CO2 levels than it really is, but we then have to explain which of the positive feedbacks that gave us the ice age to inter- glacial alternation has suddenly stopped working. We've still got sea ice around the north pole, and quite a lot of snow above the Arctic circle - probably more than we had 8,000 years ago, if - sea levels are anything to go by - that should still be working, and the water vapour as a greenhouse gas feedback depends on very basic physics and isn't going to go away until we boil the oceans dry.

-- Bill Sloman, Nijmegen

,

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As the author of the graph points out, "it is still disputed whether these were truly global or only regional events".

Leohle's reconstruction didn't have many proxies, and most of them came from around the North Atlantic.

-- Bill Sloman, Nijmegen

SNIP

It appears that NASA monitor contrails. There are also various astronomical sites commenting on them because of their affect on astronomy. They appear to be more significant at night.

Interesting NASA picture and comment here:

/quote

NASA scientists have found that cirrus clouds, formed by contrails from aircraft engine exhaust, are capable of increasing average surface temperatures enough to account for a warming trend in the United States that occurred between 1975 and 1994. According to Patrick Minnis, a senior research scientist at NASA?s Langley Research Center in Hampton, Va., there has been a one percent per decade increase in cirrus cloud cover over the United States, likely due to air traffic. Cirrus clouds exert a warming influence on the surface by allowing most of the Sun?s rays to pass through but then trapping some of the resulting heat emitted by the surface and lower atmosphere. Using a general circulation model, Minnis estimates that cirrus clouds from contrails increased the temperatures of the lower atmosphere by anywhere from 0.36 to 0.54°F per decade. Minnis?s results show good agreement with weather service data, which reveal that the temperature of the surface and lower atmosphere rose by almost 0.5°F per decade between 1975 and 1994.

/end quote

And here:

And a claim that night time contrails account for 60% to 80% of contrail radiative forcing:

/quote

Contrails and climate

Contrails, by affecting cloud formation, can act as a radiative forcing. Studies have found that contrails trap outgoing longwave radiation emitted by the Earth and atmosphere (positive radiative forcing) at a greater rate than they reflect incoming solar radiation (negative radiative forcing). Therefore, the overall effect of contrails is a warming. However, the effect varies daily and annually, and overall the size of the forcing is not well known: globally (for

1992 air traffic conditions). Other studies have determined that night flights are most responsible for the warming effect: while accounting for only 25% of daily air traffic, they contribute 60 to 80% of contrail radiative forcing. Similarly, winter flights account for only 22% of annual air traffic, but contribute half of the annual mean radiative forcing.

/end quote

Here is a report (which I haven't read beyond the intro) based on hourly observations over 12 months at 19 US Air Force Bases and Army Air Stations.

Yes, interesting photo!

So Minnis estimates .2-.3 degree C per decade of USA warming from 1% per decade increase of cirrus clouds from a general circulation model?

1% per decade increase in cirrus cloud cover does sound plausible to me.

.2-.3 degree C warming from a 1% increase in cirrus cloud cover sounds awfully high to me. By any chance does that particular circulation model predict 8 degrees C global warming from increasing CO2 to 600 PPMV?

How about I try this: Suppose 1% of the whole "effective outward radiating level" (5.5 C, 278.5 K) is covered by something completely transparent to incoming radiation, opaque to outgoing radiation, at a temperature of -50 C (223.1 K), which I consider typical of 250 millibar level - which appears to me usual for where cirrus clouds form.

This would reduce outgoing radiation worldwide by 1.4 W/m^2, out of the

492 W/m^2 Kiehl-Trenberth energy budget. To oversimplify things, using 4th root rule for 493.4/492 and 14 degrees C (287.1 K), this would cause a warming of .3 degree C/K.

Since cirrus clouds are not fully transparent to incoming radiation, almost certainly not fully opaque to outgoing radiation, and a 1% increase in cirrus cloud cover is a change over a fraction of 1% of the world, the temperature rise figures by Minnis would have to depend on a lot of positive feedback - more than actually exists?

Now, I look at:

Says current contrail coverage of the USA "over 4 months" is 1.8%. Increasing that by 1% per decade for 3 decades is .054% increase in percentage of USA covered by contrails. The article says early on that 4 times that much may be for cirrus clouds formed from contrails - that would mean increase in coverage amounting to .27% of USA's area. Assuming world-average rates, this works out to .38 W/m^2 as an upper limit, good for .055 degree C warming before feedbacks if these clouds are perfectly transparent to incoming radiation and opaque to outgoing radiation.

(The article did say that spreading contrails can cause contrail-plus-anthropogenic-cirrus 17 times that of identifiable contrails alone, but that is high side - for contrails noticed as more notably spreading.)

The article says that current contrail coverage is good for .02 W/m^2. If 4 times the linear contrail coverage is in additional anthropogenic cirrus clouds, that would be .1 W/m^2 globally, good for .015 degree C of warming before feedbacks.

.1 W/m^2 worldwide sounds high to me, but possibly true. This compares to .78 W/m^2 for CO2 increasing from 280 to 385 PPMV, using a low-side-but-credible figure of 1.7 W/m^2 for doubling CO2 and effect of CO2 varying with log of its concentration. Add to that maybe almost half that .78 W/m^2 for anthropogenic GHGs other than CO2 (thankfully largely no longer increasing).

The article did mention a concern that jetliner traffic may quintuple by

2050.

- Don Klipstein ( snipped-for-privacy@misty.com)