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Topics - F.Tnioli

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Permafrost / Impact of aircraft flights on ice melting
« on: July 17, 2020, 11:37:45 AM »
Airplane trail?

Pretty positive that's it.
Normally there would be hundreds of them in various states of dissipation, forming a veil making it difficult to so clearly see single ones:



The usual half-a-CAB "highway" between US and China&Co especially dense, as you can see. However right now, this is not the case. This recent ICAO publication provides one excellent infographic, which shows how international air travel dropped to nearly nada, and is not in any hurry to recover - note the blue line:



Thus, it is no surprise to me we now see those trails as clearly as never before: single trees are always seen in greatest detail when standing single and not in a dense forest, so to say.

I wonder if anybody could any well quantify how much of an increase this particular 2020's development had on the melting momentum increase from GAAC. Personally, i estimate it be ~12% plus-minus couple percent of an increase, averaged over whole Arctic. This is based on published pan evaporate multi-decadal measurements from a number of NH locations initially meant for agriculture but later used to estimate global dimming phenomena; yet this is not even napkin calc - only a rude guess, as i don't even fathom how to do one in this case. If someone can anyhow improve on that - please do.

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This question, i am pondering upon for years already. And it's yet far from getting any definitive answer to it.

While most concerned citizens around are primarily concerned about how _high_ sea level can rise then or then, me - i'm most concerned about _how_ sea level will rise. Personally, i doubt it'd be slow and steady all the way through.

I'd be grateful for any reasonable thoughts, estimations, geological data (such exceedingly powerful tsunamies had to happen in the past already, at very least after big asteroid impacts, so there has to be some geological evidence left).

In particular, i am most interested to learn about any modelling of effects produced by catastrophic-scale tsunamies which would produce wave over 100 meters high by the time it hits shores. I suspect such modelling was done by some few groups related to asteroid impacts (ones in the past, based on geological evidence - and/or pure modelling for possible future impacts). Yet, i didn't happen to find any detailed research of the sort, so far.

How far tsunamies of this kind of size can go through oceans? How far 100+ meters high tsunami wave would travel on "nearly level" land? How dangerous secondary and tertiary "reflected" waves would be? Will such tsunami waves would still be practically safe for ships which are far enough from any land, or not quite? Etc.

P.S. If you think the answer to all this is "definite NO, that can't happen", then please at least read this recent publication in its entirety and also this one, too. If after reading those you're still sure "definite NO", then please let me know why. I'd like to hear every possible opinion.

P.P.S. I know this matter is not about "tomorrow", "this year" or "this decade", for that matter. Most would say not even "this century" for EAIS case, i bet. But, i'm sure noone would be hurt if we'd learn things about such processes "a bit early". Besides, noone can really know if it's "way too early" to talk about it or not, because we have no idea what it'd take to dodge this kind of bullet for our globalized industrial civilization, which grows increasingly more dependant on regular, intensive and reliable intercontinental trade, most of which is done with ships and ports all around the globe.


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Science / Applicability of Stefan-Boltzmann Law to planets as a whole
« on: August 18, 2014, 03:24:08 PM »
I am no specialist in astrophysics, and i am seeking some basic understanding about whether (and how exactly) Stefan-Boltzmann Law could be applicable to rocky planets with a significantly thick athmosphere.

Few days ago, i've found a link (provided by someone in this forum; thanks!) to a simple calculator: http://www.endmemo.com/physics/radenergy.php . Entering values into the thing confirms one of my old amateurish conclusions: that considering amount of solar radiation reaching Earth and possible albedo and greenhouse effect changes, it is very unlikely to see some +10C warming (for the average annual surface temperature of Earth), and quite impossible to see some +20C or higher (both values are above-pre-industrial, of course).

For said conclusion to be valid, though, one has to assume that Earth's athmosphere is quite transparent - in both directions. Yet, we know that both water vapour and CO2 allow most of Sun's energy in (visible spectrum), but does not (as easily) allow most of Earth's own emission out - since it's in IR spectrum.

And then i had this idea: well, we have a practical example of an extremum of greenhouse athmpshere: Venus. 96,5% of its athmosphere is CO2 (with the rest being 3,5% nitrogen and some trace amounts of other gases), and it's darn thick and heavy athmosphere with that - some 9+ MPa pressure at the surface (Earth has ~0,1MPa surface pressure). What if i'd try to use the calculator to see how much different from Stefan-Boltzmann Law temperature such an athmosphere would produce at the planet's surface? Assuming that long-term, incoming energy = emitted energy in terms of the whole planet, of course.

Here are assumptions and numbers i've got when i tried:

Venus has (known from measurements):
(Bond) Albedo = 0,9  // which is drastically different from Earth's 0,306
ergo, emissivity = 0,1 (Kirchhoff's law)
surface area = 4,6E+14 meters
average surface temperature = 737 K

Using the calculator, we get: 7,7E+17 W //that's her "would be output" roughly

We also know that for Venus:
solar constant = 2611 W/m^2
crosssection = 1,15E+14 m^2 //not counting extra size her athmosphere is
ergo, input = 2611*1,15E+14*(1-0,9) = 3,004E+17 W

Obviously, Venus can not (long-term, at least) emit more than twice amount of energy than it absorbs. Any output from its core - i mean fission of uranium-like radioactive matherials, - can't be of this order of magnitude after some 4+ billions years of the planet's existance in solid form. Therefore, the only possible explanation - is that temperature of Venus' hard surface is higher because of lack of transparency of its athmosphere. If by any chance Venus would have no athmosphere whatsoever, yet its surface would still have the same 0,9 albedo (all wavelengths average) the planet has today with its athmosphere present, - then its surface temperature would be lower. How much lower? sqrt(sqrt(7,7/3,0)) lower, since it's 4th power of the temperature in the formula; i.e. 1,2657 times lower: 737 / 1,2657 = 582,3 K. Therefore, Venus' athmosphere greenhouse effect warms up the surface by 737 - 582,3 = 154,7 degrees Kelvin. No wonder, with so much higher than Earth's solar constant (Earth has it 1366,1W/m^2 iirc), and with such a "greenhouse hell" athmosphere.

The difference is significant, but not awfully dramatic. Back to Earth, our athmosphere has some ~90 times lower pressure at the planet's surface than Venus', and CO2 % content is ~250 times lower. I'd say, Stefan-Boltzmann Law is much more applicable to Earth directly, with greenhouse effect giving relatively minor effect.

Same calculations as above, but this time for Earth, albedo 0,306, surface temperature 288 K, surface area 5,1E+14 m, solar constant 1366,1 W/m^2, crosssection 1,275E+14 m^2:

"would be output" for Earth = 1,38E+17 W
actual input for Earth = 1,21E+17 W


Once again, the crosssection did not include the extra radius given by the athmosphere; this explains some of the difference. The rest (and the most) is the greenhouse effect.

Which is, finally, where i get to a question. Problem is, "official" strength of the greenhouse effect on Earth - is some ~33 K warmer than otherwise expected. This is supposed to be good science. According to the calculator, "would be output" of 33 K colder Earth (so it's 255 K for the temperature, emissivity = 1 - albedo = 0,694) - would be 8,5E+16 W, which is some 30% LESS than actual input for Earth calculated just above. Which seems quite impossible (for a body without an athmosphere and with a given bond albedo / emissivity). If to estimate Earth's greenhouse effect using the numbers above, then it seems the greenhouse effect is just 8 to 9 degrees kelvin - some ~4 times less than the official amount of +33 K. So the question is:

where's an error in my amateurish attempts to apply Stefan-Boltzman to Earth? What am i missing? ><


Thank you in advance for any help...


 

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Policy and solutions / Forced depopulation: solution or barbarism?
« on: June 26, 2014, 02:32:14 PM »
There were few people who seriously considered elimination of many (most?) people now alive as an appropriate solution for the AGW.

I've been asking myself for years: is it a solution, or is it nothing else than barbarism (to say the least)? I sitll have no decisive answer to this. Many would initially say that it's nothing to talk about, that killing people is not a solution, that the answer is clearly "no!!!" to any such plans or even thoughts. The only reason which prevents me from joining such many, - is my understanding that ultimately, the only important thing is how and for how long human species would be able to exist on Earth, and whether they would be able to exist for any long (any many generations into the future), at all. I can imagine a possible future in which some few survivors would be sitting in some cave, and discussing our times, saying something like this: "see, those idiots didn't do a thing till very last moment, adding to AGW all the time, and then they died anyways. If only they'd die few decades earlier, we wouldn't be doomed to this pityful and painful agony, as a civilization". We can't know, of course, if this is the one future we are heading to; we may _guess_ it is, but we can't ever know for sure. Still, some of really able scientists are brave enough to think and even to talk about this, and i hope someone will help me to understand this matter better right here, too.

Eric Pianka, perhaps one of most known scientists of the sort, may be not a best man around, - i just don't know, - but he's definitely a very bright biologist, and he did a whole ton of field work, so ain't no "pen and paper" guy, too. In case some people here are not familiar with his famous speeches on the subject, - here's a tip of the iceberg: http://www.pearceyreport.com/archives/2006/04/transcript_dr_d.php .

P.S. Oh, and if you wonder why i ask about this now (and not before) - well, http://www.msf.org/article/ebola-west-africa-epidemic-requires-massive-deployment-resources . Makes one think, eh.

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