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David Nemerson
Baltimore
Estuarine ecologist and deeply concerned citizen
Recent Activity
Gah - Bill you are correct! As albedo decreases energy absorption will increase. You are not at sea. Yeah, sorry we're flogging a dead horse here. I'm not not questioning the death spiral in way and expect close to a full melt out in the next few years save for a few vestigial holdouts (although the placement of the thick ice above the Fram right now suggests that any hold out will be pretty small). I also agree that once all the ice is gone, arctic amplification might well run away. I was only trying to gain some clarity and improve my understanding of how this issue of the enthalpy of fusion plays in. Andy, the loop you present includes a host of factors but doesn't even mention the fact that the same amount of energy needed to change the phase of a gram of ice to water will raise that gram of water 80 degrees. I guess that's basically an acknowledgment that the arctic is NOT a pan of ice water being steadily heated from below (which I'm well aware will behave as you say). So, my intuition is completely in agreement with yours, given all the factors you name. What I'm (still!) less sure about is how important the latent heat of fusion of ice to liquid water is in the overall dynamic.
Toggle Commented Feb 5, 2017 on A new Arctic feedback (?) at Arctic Sea Ice
Wow, Andy, I don't think you read what I wrote at all. Obviously "Once all the ice melts, it can no longer act as a buffer to clamp the temperature." That's not the question and your statement about "we have science" is pretty condescending. I'm a PhD biologist and I asked a sincere question. I specifically asked about the effect of albedo as it is my understanding that that is what will drive increased arctic amplification, NOT the fact that incoming energy will not longer be devoted to the extra energy needed to change phase from solid to liquid. As I have repeated every time I've brought this up, a poster above asked specifically about the issue of the latent heat of fusion. And I have said that I have read in many places that "once all the ice melts all that energy the used to overcome the latent heat of fusion will now go into raising the temperature." That's a totally different thing than "dark oceans absorbs heat (albedo)." I am certainly not engaging in hyperbolic language. But the first link - the first Google hit - does have this language: "By now, any reader still with me will have concluded that this cooling will be short-lived, and we are currently enjoying the maximum of its cooling effect. Although the ice will continue to melt faster and faster, it's total amount will continue to dwindle, and the amount of LHF absorbed will decline, eventually to zero when there is no ice left. At that point, because there is nothing left to absorb the quintillions of calories in LHFs, global warming speed will take a quantum leap, as if someone had cranked the dial to 10." All I'm saying is THAT seems hyperbolic to me. This is a continuous process. There is not some point in time when suddenly the "needle goes to 10" because there is zero ice left. This seems pretty straightforward to me. And I think that's what Geert was asking about. I wasn't saying that the increased albedo won't increase arctic amplification! Geez.
Toggle Commented Feb 4, 2017 on A new Arctic feedback (?) at Arctic Sea Ice
Yikes, thought I was pretty clear! Someone else else here posed a question: "Hello there, I am wondering what will happen if in a few years no ice will be left over in the arctic to melt... the heat that now goes into the ice to melt it, must go somewhere else like the sea itself and I am wondering if models have taken into account the extra accelleration (feedback) this will bring about in the rising of arctic and global temperature rise... this must be, I guess, a big contributor to extra heat absorption in the oceans..." Answering this is pure physics. No complexity required! No ice movement, no questions about when high, when low. None of that! No new water vapor and storminess regime. Nada! Just looking for some simple confirmation. The energy required to change phase from solid to liquid is returned to the system when the liquid refreezes. In a given year the enthalpy of phase change is balanced as long as the melt and the freeze are equal. But, the size of the ice cube IS shrinking and will continue to shrink. So my question is, does this statement make sense?: "Once all the ice is gone all the energy that used to go into melting ice will go into heating water and the rate of arctic amplification will accelerate." It seems to me it does not. The ice cube has melted over a period of decades and there is nothing magic when the last little bergy bit goes. There is no discontinuity there. The energy that it took to melt the ice over decades is just part of the ongoing and increasing energy imbalance of the planet and has all already been accounted for. There are tons of posts on the interwebs saying things like "Oh my god, the amount of heat required to melt a gram of ice will increase a gram of water by 80 times as much (or is it 160x)! Once the ice melts were screwed!" This is BS. That's all I'm trying to confirm. Because Geert asked!
Toggle Commented Feb 4, 2017 on A new Arctic feedback (?) at Arctic Sea Ice
Zebra, Geert asked "Hello there, I am wondering what will happen if in a few years no ice will be left over in the arctic to melt... the heat that now goes into the ice to melt it, must go somewhere else like the sea itself and I am wondering if models have taken into account the extra accelleration (feedback) this will bring about in the rising of arctic and global temperature rise... this must be, I guess, a big contributor to extra heat absorption in the oceans..." If the same amount of ice melts as freezes every year, the equation is balanced. I get that. And that's why I pointed out that while the ending volume is now less than it used to be, the annual flux is about the same. What you seem to be saying is that there is no net effect whatsoever. You can freeze and thaw a lot of ice every year or no ice every year. Energy in, energy out, no difference. And that makes intuitive sense. When you hear people say things like "Once the ice all melts, all that energy that used to go into melting ice will go into heating up the system" that's fundamentally wrong? Yes, we got rid of a few thousand cubic kilometers of ice over several decades and that had some fairly small effect on the energy balance of the planet, but there is no looming feedback whatsoever. Right?
Toggle Commented Feb 4, 2017 on A new Arctic feedback (?) at Arctic Sea Ice
Thanks Bill. I realize the arithmetic is trivial; it's really the thermodynamics I'm trying to wrap my head around. Geert, above, basically asked if the latent heat of fusion is a big deal in the arctic, or not. You are completely correct in pointing out that comparing the latent heat embodied in the 10 or 11,000 cu km loss in summer volume minimum over the past decades and the excess heat stored in the oceans in one year is apples to oranges. I'd go one further and say that comparing the dynamics of latent heat in the arctic to long term storage of the mounting global energy imbalance (mostly in the oceans) is a pretty meaningless way of looking at this issue. I did look at Wip's graphs and went ahead and downloaded the data. According to PIOMAS, the total volume of ice created and then melted every season hasn't really changed that much. It is generally in the 15-18,000 cu km range every year and has actually increased a bit in recent years. So, during recent melt seasons, if anything more energy is being "spent" on the latent heat of fusion than earlier in the record. So, my, and I think Geert's question is, as this stage of the arctic's decline transitions into one where there is just less ice to melt each year, and less energy is needed to change phase, will that have a big impact on the energy budget in the arctic? For the sake of argument, let's imagine an upcoming season where the max is low enough to melt out by, say July 1 (even if there is still some vestigial ice around the CAA or whatever). Will the fact that no energy will need to go into melting for the remainder of that season have a big impact on the energy budget? Is this effect swamped by albedo for example? I apologize if the answer to this is well known. There does appear to be some serious handwringing on the web about the problems this will cause. Thanks.
Toggle Commented Feb 4, 2017 on A new Arctic feedback (?) at Arctic Sea Ice
Assuming your correction is right, it does affect the conclusion, doesn't it? The earthscience link says it would take 3.7 x 10^18 joules to change phase of 11,000 cu km of ice from solid to liquid. You suggest it's more like 3.3 x 10^21. The reference goes on to say that the oceans are absorbing 2 x 10^23 joules per DECADE or 2x10^22 per year. So is the latent heat thing is actually within one order of magnitude of the total amount of excess heat going into the oceans per year? That does not strike me as "minuscule". This calculation would appear to refer to the amount of heat that is no longer devoted to melting already lost ice, not the amount that will no longer be needed in the future contributed by further ice loss. I'll try and dig deeper into this. Can someone more familiar with this math weigh in?
Toggle Commented Feb 3, 2017 on A new Arctic feedback (?) at Arctic Sea Ice
I googled "Latent heat of fusion arctic ice melt" Here are a few hits: http://www.occupyforanimals.net/how-the-climate-will-change--the-role-of-latent-heat-of-fusion-in-global-warming.html http://arctic-news.blogspot.com/p/latent-heat.html and: Latent heat is a factor, but is completely eclipsed by the rate of global warming. For example, since 1978 the April (maximum) Arctic sea ice has decreased in volume by about 11000 cubic km. The latent heat absorbed by the ice to achieve this is about 3.7 x 10^^18 Joules. Compare this to the amount of excess heat, which has been absorbed by the oceans, which is about 2.0 x 10^^23 Joules per decade. That is, some three to four orders of magnitude more heat than the decadal heat required to melt the Arctic ice. Of course there are complications of the heat absorbed by land (much less than in the oceans), melting of Greenland and Antarctic ice sheets, and uncertainty over the depth of oceanic warming, due to sparsity of measurements, especially in the southern hemisphere. But however you cut the statistics, the latent heat is minuscule compared to the planetary heat imbalance. http://earthscience.stackexchange.com/questions/6527/is-global-warming-being-moderated-by-latent-heat-of-melting-polar-ice
Toggle Commented Feb 3, 2017 on A new Arctic feedback (?) at Arctic Sea Ice
Could you add the global volume graph that Wipneus posted on the forum?
There is a good discussion on the Forum about this issue. See here, starting with Bill Fothergill's post #1761: http://forum.arctic-sea-ice.net/index.php/topic,1611.1750.html
Toggle Commented Jan 6, 2017 on Global warming 2016: Arctic spin at Arctic Sea Ice
I think the super rich are more of a symbol of the problem than the problem itself. A cap on total wealth would do nothing to tame the material ambitions of the two billion eager to enter the global consumption class. There has to be a more universal change in the global zeitgeist that values non-material goods like leisure, community, togetherness, quality, arts, health and more, over material acquisition. The median lifestyle of a European would be far too great to imagine for the 7.4 billions humans now, much less the 10 billion of the future.
Toggle Commented Jan 5, 2017 on Global warming 2016: Arctic spin at Arctic Sea Ice
At a 1.11% growth rate a population doubles every ~63 years. That is exponential growth. If the growth rate slows in the future then the doubling time will increase. But a population with any positive, intrinsic rate of growth, measured at a moment in time, is growing exponentially. Is this a true statement?: "Exponential growth which exponent decreases with time ... is not exponential growth." I honestly don't know. I would think that as long as the growth rate remains above zero it is growing exponentially because the population will grow indefinitely and in a compound fashion. What if you knew the growth rate would asymptote at 1.00%? "r" would still be falling every year but would you really say it was not growing exponentially as the doubling time would also asymptote at ~70 years? FWIW, I have little doubt that the exponent will fall to zero and go negative, likely within a few decades.
Toggle Commented Jan 5, 2017 on Global warming 2016: Arctic spin at Arctic Sea Ice
AJbT: Global population is currently growing at about 1.11%/yr. That is exponential growth. "Population in the world is currently (2017) growing at a rate of around 1.11% per year (down from 1.13% in 2016). The current average population change is estimated at around 80 million per year. Annual growth rate reached its peak in the late 1960s, when it was at 2% and above." http://www.worldometers.info/world-population/
Toggle Commented Jan 5, 2017 on Global warming 2016: Arctic spin at Arctic Sea Ice
Feel the need to add that continuing to burn sh*t while engaging in any sort of Solar Radiation Management (SRM) does nothing to address ocean acidification. It is hard to imagine that humanity won't embrace SRM as a license to keep on keeping on. The only possible hope is if some near-magical paradigm shift sweeps across the globe ushering in a post growth, non-materialist ethos. Unwinding our inherently unstable, growth-based global financial system is as wicked a problem as the technological issues around renewable energy, nonrenewable resource depletion, sustainable agriculture, etc.
Downpuppy: Yes! The rate of decline for the past 5 days (extent) dwarf's the rate for the same 5 days from 2012. By 35% ish. I would guess that the current condition of the ice makes all correlation analyses more or less irrelevant.
Toggle Commented Jul 2, 2013 on Problematic predictions 2 at Arctic Sea Ice
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Jul 2, 2013