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Post by Pttg on Jun 2, 2017 20:10:49 GMT
Ah, so we do have a denialist here. Capable of agilely leaping from cherry-picked data to faulty conclusion, without touching a clue along the way.
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Post by newageofpower on Jun 2, 2017 20:28:10 GMT
Even the Paris agreement wouldn't have been enough. The only faith I have right now in countering climate change is through geoengineering. (Aerosol injection, active carbon scrubbing, etc.) Solar shades! Full SMAC! Ah, so we do have a denialist here. Capable of agilely leaping from cherry-picked data to faulty conclusion, without touching a clue along the way. Hey man, I respect you quite a bit for your normally high-quality and informative posts, but can you cut it out with the shitty ad-hominems? At least, post some SCIENCE! of your own to counteract his claims, thanks. I was 2 seconds away from flaming you, but I like you... Let's not do this again.
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Post by thorneel on Jun 2, 2017 20:31:04 GMT
apophys I was going to steer away from this due to having developed kind of heterodox opinions on it last years, but to add to it... In the last IPCC report (the one from 2015), if you take the data on temperature and CO2 by time, use a light low-pass filter on them (Excel is good at that) and compare them, you may notice that CO2 clearly seems to be following temperature variations with a 6 months delay. There may be good explanations, but the weird thing is that AFAICT there is no explanation nor even observation of this fact in the report itself, which you would expect in such a serious, reference document. Also, there is no word on the effect of wild biomass (as opposed to the much less massive cattle biomass), a rather, well, massive CO2 factor. (Most of said mass is micro-organisms) Also, there is a theory based on different models linking temperature variation with solar activity (not temperature, activity has more to do with particles and cosmic rays received than photons received). The theory may be disproved, I don't know, but again, no word on it. Interestingly, we actually don't know much about how clouds (a rather capital factor there) form, and some recent works link it to cosmic rays. So stop emitting CO2 if you want - thermal powerplants ( COAAAL!!!) and mass hydrocarbon car traffic is rather unhealthy, after all (though be careful with alternatives). But don't you even think about starting active climate engineering.
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Post by shiolle on Jun 2, 2017 21:45:01 GMT
The conclusion to draw is that either temperature is dictating CO 2 levels, or that some third factor controls both of them (more likely). In fact, insolation is a great candidate for the controlling factor: I'm afraid there is a bit of confusion here about the question we are trying to answer. The graph shows the onset and recess of the ice ages. The lag you describe means that changes in atmospheric CO 2 didn't cause their beginning or the end. Neither insolation nor CO 2 could be the final answer to what causes ice ages because that would immediately beg the question what causes changes in CO2 and insolation. You may notice that those cycles are quite regular, so their ultimate cause must also be some regular process. And the likely answer is Milankovitch cycles. I will return to them in a bit. But it wasn't the claim that CO 2 changes started or ended ice ages. The claim was that CO 2 is a greenhouse gas and if its concentration increased, it would make the planet to heat up. So: - Does this data prove that CO2 doesn't affect temperature? No. CO2 is considered a greenhouse gas because it can absorb and emit infrared light.
- Does this data indicate that rising temperature can increase atmospheric levels of CO2? Yes, and this is most likely due to changes in CO2 solubility in ocean water with temperature. So as the temperature raises more CO2 is freed from the ocean which causes further rising in temperature which again raises atmospheric levels of CO2 and we have what is called runaway greenhouse effect. To reverse this positive feedback loop there should be some outside factor, and that is likely the changes cycles I mentioned.
- Does the Malinkovitch cycles alone fully explain changes in temperature? No, they don't. The correlation isn't perfect and it appears that in absence of other factors their effects should be much less pronounced, so there has to be something that greatly amplifies the effects of orbital changes. What could that be? Well, if you look again that the combined graph for CO2 and temperature you might notice two things:
- The lag is between them is larger when the temperature is dropping.
- The temperature raises rapidly but falls slowly.
So, this is thought to be the evidence that CO2 can amplify temperature increases and that it takes time for it to be reabsorbed by the ocean.
Actually, global biodiversity hasn't particularly cared for either temperature or CO 2 levels. Compare this with my long-term view above: Our current mass extinction has much more to do with habitat destruction, pollution, and over-harvesting (imho). The problem for biosphere, if I understand it correctly, is not as much the magnitude as the rate of changes. The onset of an ice age took thousands of years; now we may be looking at changes of similar magnitude in the span of two or three centuries. The fear is that many types of plankton won't have time to adapt and that causes significant chain reactions up the food chain. Of course, other factors you mention pose a severe threat too, but temperature changes are much more important for marine rather than land life. P.S. It would be really great to hear petrifiedwalnut opinion on this, but alas I think it is unlikely.
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Post by apophys on Jun 3, 2017 0:29:55 GMT
Neither insolation nor CO 2 could be the final answer to what causes ice ages because that would immediately beg the question what causes changes in CO2 and insolation. You may notice that those cycles are quite regular, so their ultimate cause must also be some regular process. And the likely answer is Milankovitch cycles. I understand that insolation means the sum total of radiation accepted by the Earth from the sun. In which case, Milankovitch cycles are part of the cause of changes in insolation (I'm not very knowledgeable here though; I'll read up on them). I expect that long-timescale variations in the sun itself are part of the rest of the answer. The fact that it is a greenhouse gas just means it is an insulation blanket for the planet; it does not quantify how large of an effect this is. The data suggests that the effect of CO 2 variation is small compared to the real driver of the cycle. Yes, it indicates that rising temperature increases atmospheric CO 2, but the converse is not visible in this data. A runaway effect should result in an exponential increase in both temperature and greenhouse gas, which does not appear to be the case on the rising portions (they look approximately linear). Also notice that we are currently just after a peak. So if a runaway effect does happen, it already happened ~20,000 years ago and ran out of steam (pun intended; water vapor is also a greenhouse gas). Consider the analogy of a greenhouse. It accepts light through the glass, which then becomes heat and is trapped. Thus it warms up very quickly during the day. At night, it releases its heat, but it does this slowly, due to thermal mass and the insulation by the greenhouse glass. (This is indeed what happens in a regular greenhouse.) Compare a warming period to day and a glaciation to night. This thought experiment is consistent with the fast rise and slow fall seen. Adding glass will not accelerate heating, but it will certainly slow cooling. No runaway effect is necessary to explain the bulk of the observations; thus if there is one, it must be small. The rate of adaptation of weeds to herbicide, of bacteria to antibiotics, and of mosquitoes to DDT, suggests that is unlikely to be a huge problem. A few hundred years is not enough for speciation, but it is certainly enough for a few genes to appear or dormant genes to re-emerge. That being said, I don't know of the timescales of the changes involved in past mass extinctions.
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Post by The Astronomer on Jun 3, 2017 2:49:10 GMT
Say good bye to the marine ecosystem and biodiversity, say hello to more extreme weathers, hotter climate and new deadly diseases (or old ones which got released from the thawing permafrost). Actually, global biodiversity hasn't particularly cared for either temperature or CO 2 levels. Compare this with my long-term view above: Our current mass extinction has much more to do with habitat destruction, pollution, and over-harvesting (imho). See: Ocean acidification. Ocean acidification (and pollution) destroys coral reef, which is home to millions of species. I think I saw both habitat destruction and pollution I don't blame apophys for being skeptical. It's healthy, but it seems like he's misunderstanding something?
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Post by apophys on Jun 3, 2017 4:02:45 GMT
I don't blame apophys for being skeptical. It's healthy, but it seems like he's misunderstanding something? I may indeed be misunderstanding something. If so, I would like to be pointed out where...
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Post by The Astronomer on Jun 3, 2017 4:08:48 GMT
I don't blame apophys for being skeptical. It's healthy, but it seems like he's misunderstanding something? I may indeed be misunderstanding something. If so, I would like to be pointed out where... Well, I'm no expert (except you want a Star Wars-level verbal battle), so I guess I'll sit back and get a popcorn.
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Post by shiolle on Jun 3, 2017 6:33:49 GMT
I understand that insolation means the sum total of radiation accepted by the Earth from the sun. In which case, Milankovitch cycles are part of the cause of changes in insolation (I'm not very knowledgeable here though; I'll read up on them). I expect that long-timescale variations in the sun itself are part of the rest of the answer. The important caveat here is that insolation is the power received on Earth per unit area on a horizontal surface, i.e. insolation is solar irradiance measured at Earth surface. The difference between solar irradiance at the top of the atmosphere and at the Earth surface can be quite dramatic: The graph you provided for insolation thus already includes in it the insulation effects of greenhouse gases. I am sorry, I would like to talk more about it but right now I have very little time. One point I would like to address though is this: This thought experiment is consistent with the fast rise and slow fall seen. Adding glass will not accelerate heating, but it will certainly slow cooling. No runaway effect is necessary to explain the bulk of the observations; thus if there is one, it must be small. I think the analogy here is incomplete because in our case the glass is getting thicker as the temperature inside the greenhouse rises because warmer sea water can solve less CO 2 and thus as the ocean warms, CO 2 concentration in the atmosphere increases. This slows the cooling further thus increasing the net energy absorbed by the Earth. I would be glad to give a more complete answer when I get home during the weekend.
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Post by apophys on Jun 3, 2017 7:53:22 GMT
The fear is that many types of plankton won't have time to adapt and that causes significant chain reactions up the food chain. I found some interesting information on this issue. 1. www.ecoanalysts.com/2015/12/16/evolving-phytoplankton-can-tolerate-warming-waters/"A study conducted by the University of Exeter in Cornwall, England, found that phytoplankton exposed to warming temperatures modeling those expected at the end of the century initially failed to thrive. However, at the end of 45 days (approximately 100 generations) the populations showed an evolving tolerance for the increased temperature. The experiment also showed that as the water temperature rose, the phytoplankton were able to absorb more carbon dioxide compared to the amount of carbon dioxide absorbed at the current water temperature." "The researchers used a common phytoplankton species Chlorella vulgaris (typically utilized in climate modeling)" "The researchers held the temperature steady at 33 degrees for 100 generations, and during that time, the growth rate increased exponentially showing that the species evolved from exposure to the warm conditions." 2. www.sciencedaily.com/releases/2015/12/151217151533.htm"The groundbreaking study, published in the journal PLOS Biology, was carried out over five years using artificially warmed ponds that simulated the increases in temperature expected by the end of the century. The researchers found that phytoplankton in ponds that had been warmed by four degrees, had 70% more species and higher rates of photosynthesis" "In contrast to previous work conducted in small scale, short-term laboratory experiments, these findings demonstrate that future global warming could actually lead to increases in biodiversity and photosynthesis in some locations. These results cannot be extrapolated to the global scale as declines might occur in other places where different ecological mechanisms prevail." "The authors attribute their findings to the fact that the experiments were conducted in open outdoor ecosystems where local extinctions of species can be replaced by new immigrants from surrounding locations."
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Post by The Astronomer on Jun 3, 2017 7:59:18 GMT
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Post by thorneel on Jun 3, 2017 9:24:19 GMT
(This is indeed what happens in a regular greenhouse.) That's what was thought until a few years ago when a trollish German team demonstrated that regular greenhouses don't actually use greenhouse effect. Instead, they prevent convection (which is the main heat equalisation mechanism anyway) and, to a lesser extent, conduction, but do pretty much nothing about radiation. But then if greenhouses don't use the greenhouse effect, how should we call them?
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Post by The Astronomer on Jun 3, 2017 9:30:38 GMT
(This is indeed what happens in a regular greenhouse.) That's what was thought until a few years ago when a trollish German team demonstrated that regular greenhouses don't actually use greenhouse effect. Instead, they prevent convection (which is the main heat equalisation mechanism anyway) and, to a lesser extent, conduction, but do pretty much nothing about radiation. But then if greenhouses don't use the greenhouse effect, how should we call them? Wait a minute. I thought infrared light cannot travel through glass.
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Post by apophys on Jun 3, 2017 9:57:16 GMT
www.icriforum.org/about-coral-reefs/status-and-threat-coral-reefs"Overfishing, pollution and coastal development top the list of chronic stressors." "Fishing with dynamite, cyanide and other methods that break up the fragile coral reef are highly unsustainable." " Fishing with dynamite" www.scientificamerican.com/article/coral-reefs-show-remarkable-ability-to-recover-from-near-death/"reefs that weathered 1998 proved even more resilient in the 2010 bleaching event off Indonesia. "Many reef corals just might be capable of adapting fast enough to survive current rates of global environmental change," wrote marine biologist John Pandolfi of the University of Queensland" www.bbc.com/earth/story/20140916-the-corals-that-come-back-from-the-dead"Based on the known growing rates for the species, Mumby predicted it would take the Porites nearly 100 years to recover, not 15. “Our projections were completely wrong,”" en.wikipedia.org/wiki/Coral_bleaching"Coral in the south Red Sea does not bleach despite summer water temperatures up to 34 °C (93 °F)." "In 2010, researchers at Penn State discovered corals that were thriving while utilizing an unusual species of symbiotic algae in the warm waters of the Andaman Sea located in the Indian Ocean. Normal zooxanthellae cannot withstand temperatures as high as in that location, so this finding was unexpected. This gives researchers hope that with rising temperatures due to global warming, coral reefs will develop tolerance for different species of symbiotic algae that are resistant to high temperature, and can live within the reefs." "10% of the world's coral reefs are said to be threatened by coral bleaching induced by sunscreen alone." Don't get me wrong; warming is definitely bad for coral, but it's probably survivable long-term. If we stop blowing them up and dumping sewage and cyanide and sunscreen...
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Post by The Astronomer on Jun 3, 2017 10:01:11 GMT
Don't get me wrong; warming is definitely bad for coral, but it's probably survivable long-term. If we stop blowing them up and dumping sewage and cyanide and sunscreen... Are you serious with that? Half of the coral reef is bleaching right now.
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