So there was this exchange in the ameripol w/r to California forest fires vis-a-vis climate change. I promised I'd follow up on it, but then decided not to because I've been having an episode of 'thinking is hard and what's the point of anything'-ism.
But eh, now some article or whatnot reminded me of it, so let me make my points.
Totally forgot the fucking aussie trees, and no, it has little to nothing to do with the climate for a simple reason: warmer climactic periods are LESS arid, sounds crazy but the reason we have large deserts now is because of all the water locked up in various ice caps. Just because the idea seems intuitively fine that hot=arid it doesn't matter if reality disagrees, same with the projections of increased storm intensity/frequency which somehow overlook that storms are driven by the magnitude of the local temperature differences from the equator to the pole, guess what goes down in a warmer planet?
[citations needed]
For what, aridity being higher during glacials? For fucking carnot heat engine efficiency? I thought you knew this stuff man.
This post was there too, for full context:
"DID YOU JUST...
...Ignore the possibility of droughts caused by changing weather patterns worsened by climste change?
When they're presented as a broad and widening thing? Fuck yes I did, it is lying to the layman and it is the worst sin in science. Ice ages are arid, deserts expanded vastly, the sahara is a remnant of the glacial deserts, you want to see what happens when you have a massive ice sheet, look at Antarctica, the largest desert on the planet, literal fucktons of water right there, hard as rock, dry as stone.
To assume that THIS point in time is when we reach the apex of aridity and that it somehow drops off if we enter a warmer climate AND a colder climate is absurd just from a philosophical standpoint, nevermind the physical implausibilities required to support this idea. Somehow we're going to melt the last ice caps and simultaneously turn half the planet into deserts?
I get it, burning oil is shitty, I love cars but we have better things to do with petroleum anyways, and burning lighter distillates of it isn't one of them. Moving away from oil and coal and gas is important, but I can't help but think honesty in the presentation of science is important as well. A big part of that is being able to say "I don't know" or better yet "I'm not certain, but if X holds, then Y following is supported by Z models for these reasons with these assumptions as can be found in blah blah blah" which will probably end up with your audience having their eyes glaze over sadly. I always liked reading through this stuff, but I had to swear off arguing about it, too much time I could have been doing something fun like hurting myself with woodworking tools or picking my nose. I'll gladly provide links to read through and make your own inferences from if you're interested, with the note that you shouldn't believe me, as I do not have perfect information about the future or the past, nor does anyone else. Asking questions and hunting for answers is always a noble pursuit.
Changes in the water cycle are projected to occur in a warming climate (TFE.1, Figure 3, see also TS 4.6, TS 5.6, Annex I). Global-scale precipitation is projected to gradually increase in the 21st century. The precipitation increase is projected to be much smaller (about 2% K–1) than the rate of lower tropospheric water vapour increase (about 7% K–1), due to global energetic constraints. Changes of average precipitation in a much warmer world will not be uniform, with some regions experiencing increases, and others with decreases or not much change at all. The high latitude land masses are likely to experience greater amounts of precipitation due to the additional water carrying capacity of the warmer troposphere. Many mid-latitude and subtropical arid and semi-arid regions will likely experience less precipitation. The largest precipitation changes over northern Eurasia and North America are projected to occur during the winter. {12.4.5, Annex I}
Italics theirs, unnecessarily vague wording which could suggest a majority of regions bolded by me, link here: https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_TS_FINAL.pdf
Now then. If I do know anything, is that simple answers to complex question tend to be red herrings. And probably more importantly, that one should trust certified experts (I ain't one) over one's own insight, because we only ever see Dunning-Kruger in other people.
I don't have a problem with the claim in the first quoted bit that warmer globe = higher average global precipitation. That indeed seems to be the case.
I have a problem with almost everything else in there, because the connections and inferences you're making from that one fact seem to me unjustified, running contrary to what I've been reading.
In broader terms, in that post there are two claims, one about the fires vs humidity, and one from the left field about the storms.
But let's try and break them down into smaller bits:
(...), and no, it has little to nothing to do with the climate for a simple reason (<-1->): warmer climactic periods are LESS arid (<-2), sounds crazy but the reason we have large deserts now is because of all the water locked up in various ice caps (<-3). Just because the idea seems intuitively fine that hot=arid it doesn't matter if reality disagrees (<-true dat), same with the projections of increased storm intensity/frequency (<-4) which somehow overlook that storms are driven by the magnitude of the local temperature differences from the equator to the pole (<-5), guess what goes down in a warmer planet (<-6)?
1.
This is an unjustified connection. It assumes the process at hand (fuel aridity) is driven solely by this one variable (global average precipitation). One would have to substantiate why it's a reasonable thing to assume. From I've read, w/r to the Canadian taiga fires some time ago, increasing temperatures cause increased evapotranspiration that easily exceed gains from increased precipitation. The precipitation would have to increase over 15% per degree Celsius to come out even. So existing forests get drier, even as the air may get more humid. This runs contrary to your claim.
(I think
this is where I read it. It references the ABoVExperiment, but I don't know from where exactly.)
2.
This is one of the two claims you decided to focus on in your brief response. But it's nearly the only one I don't have a problem with. It's true and it's easy to confirm that it is so. It's not a problem, that is, as long as one remembers that it's global average humidity. Because if one starts to try and justify something, regardless of its validity otherwise, about local conditions - e.g. about frequency of forest fires in California or some other relatively small region - then one shows a lack of understanding of what average and global means.
So, even if it were true that higher precipitation=lower fuel aridity (and it doesn't appear to be, cf. 1.), one would have to show that this global and average trend governs fuel aridity in California, specifically.
I'm not sure if I really have to explain this further. In spatial terms, what does it matter for desertification (Arizonization?) of California, if Sahara gets all green? Would you tell a farmer in Syria that it's not true his crops don't get enough rain because more precipitation in the Arctic means the globe gets more moist? Same with the temporal dimension - e.g. get a lot more snow in winter, but relatively less rain during whatever is the driest season, and fire risk increases while average precipitation goes up.
3.
This is another odd connection that I don't know on what basis you're making. Why would the water specifically from disappearing ice caps end up watering the deserts? Why would it not just drain to oceans? Why would increasing global humidity be needing this water, instead of just ocean water and higher temperature permitting more water vapour in the air?
The way I understand it, quite a lot of river systems are supplied by seasonal melts of glacial caps in various mountains. Take away those glaciers, and the rivers drain fully or partially. You'll end up with higher global humidity, but with new deserts all the same.
It's again the same issue as with (2) - global warming causes local climate change.
4.
As long as this is about tropical cyclones, and not some other storms, the prediction is not that of increased intensity and frequency. It's that frequency on average goes down, but frequency on the high-intensity end of scale goes up. Less storms overall, but more strong ones.
5.
Are they, though? Are any locally forming storms driven by that? Like, again, how do you make the connection? Even tropical storms don't span the entire globe, and the explanations for how they emerge that I saw don't require a steep temperature gradient between the equator and the poles. What they (again tropical storms, because I think that's what's usually referred to in this context) need is an energy reservoir in the form of warm ocean water, together with calm winds so that the forming storm does not get disrupted and some other conditions described e.g. here:
http://www.aoml.noaa.gov/hrd/tcfaq/A15.html.
6.
Yeah, man, agreed. That temperature gradient goes down. Is that what you meant by 'Carnot engine efficiency'? Then it's again trying to apply a piece of physics where it's not applicable, and trying to reduce a complex systems to a single variable.
The way I see it, as far as reasoning goes, what you're doing is in the same category as the 'it's the sun, stupid' argument. It's learning some relatively simple but maybe obscure fact about some process, assuming that's all there is to know about it, and (mis)using this newly gained knowledge to prop up some pre-existing world view (which I think in this case is: climate scientists/IPCC are lying to children and/or being alarmist).
Climate scientists hate him. Use this one simple trick to quickly understand what professionals spend years to understand - is what I'm seeing.
The point is, reading a paper or a bunch is not sufficient, if one doesn't have the background to understand how it fits in the larger context of the relevant body of knowledge.
That's why we have experts - professional researchers working full time on understanding how this or that aspect of climate change works.
So if the experts tell me climate change contributed and will continue to contribute to Cali fires*, while Max tells me nuh-huh because he's got this silver bullet of a factoid, then I know which to believe.
*and they do. Here are the sources I got from just one article on the subject, discussing some (all?) of the CC-related contributing factors, published by a (non-English) public outreach
website for climate science:
Extremely low precipitation in California this seasonIncreasing precipitation volatility in twenty-first-century CaliforniaClimate change projected fire weather sensitivity: California Santa Ana wind occurrenceProjected changes in persistent extreme summer weather events: The role of quasi-resonant amplificationImpact of anthropogenic climate change on wildfire across western US forestsI'm not actually suggesting anyone needs to read that. Rather, find a similar English-language public outreach project, led by actual climate scientists, that puts such research into digestible context. Because that's invariably going to be a better source than yours or mine shallow understanding.
Author
Topic: Science Thread (and !!SCIENCE!! Thread!) (Read 87618 times)