UVB radiation was the Devonian-Carboniferous extinction kill mechanism
advances.sciencemag.org
advances.sciencemag.org
Did not know this worrisome hypothesis. The idea that a warming world could inject more reactive material into the stratosphere via convective storms seems reasonable. Thanks a lot for one more reason not to sleep tonight.
Scientists really need to learn how to keep it to themselves for like a year or two. /s
http://burro.case.edu/Academics/USNA229/impactfromthedeep.pd...
People don't have a mechanism to "inject ozone" into the stratosphere (we count on the Sun to do that) so if it were removed again, we would all likely die.
Similarly, at least one extinction event was due to volcanism, another thing we puny humans have no means to control (as much as I would love to be able to).
It is not disloyal to the global warming cause to acknowledge that there are things that we aren't responsible for that could kill us too.
I thought there was something funny about the abstract...most abstracts in high profile journals have a much different tone.
Open access journals like Advances or Nature Communications are not that bad, but Nature Scientific Reports is horrible.
It's very low impact journal with minimum review. It's intended to be place for grey literature where technical reports and scientific reports with no importance go. Unfortunately it has started to publish junk science too. Those pieces get posted into HN frequently. All that happens under nature.com that makes them seem legit.
And junk science? Please provide links.
More on Scientific Reports, And on Faked Papers https://blogs.sciencemag.org/pipeline/archives/2016/06/15/mo...
They are supposed to do very light peer review just trying to check if the article is technically sound. Apparently even that review process is broken.
As a matter of fact you can get plenty of crap into the higher tier Science/Nature journals if you just tell a good enough story about importance. You can leave the real work to disentangle whether the story is true to others that can publish in lower impact topical journals.
Generally speaking I believe Science and Nature, and the role they occupy in academia, are a major problem for science. They are huge contributors to overselling and hype driven research.
Sometimes the curation role of a journal is important and peer review can identify errors. In this case it seems like access to the right geological formations by competent scientists is key and I read nothing in the paper made me question the science. I don’t think the lack of journal prestige diminishes the significance of this specific paper; it probably reflects the modern relevance of this extinction event.
I think it's not just a problem on this website; social news link previews also show the domain and favicon which might mislead people as to how high-profile the paper is.
of course, being in a high-impact journal doesn't guarantee good science at all. but it still does lend some credibility.
“Available to the public online since 1996, PubMed was developed and is maintained by the National Center for Biotechnology Information (NCBI), at the U.S. National Library of Medicine (NLM), located at the National Institutes of Health (NIH).” [1]
https://en.wikipedia.org/wiki/Late_Devonian_extinction (376–360 Mya)
That's the ref in the paper. It's a bit confusing because they're looking at chemical processes taking place at 15-20km altitude. Temps there are around -55C maybe, 200K).
They plot changes for activation of the process, but I don't have enough knowledge about it to understand the implications. The bottom axis of their graph runs from 195K - 210K though so clearly it's not a big delta. They seem much more interested in the amount of water vapor at altitude.
The other thing is that it seems like the process has a fairly short cycle time. By which I mean they mention changes on the order of days. When I think about ozone holes I think mainly in the context of decades.
So I'm not sure how much the mention of warming and ozone loss in the OP paper was a 'hey that might be of note,' or was a more substantially linked relationship.
(I kind of wonder if pole reversal/magnetic field weakening or solar events could play into the loss of ozone during the extinction in the original paper?)
The paper makes this statement at the end:
Last, we emphasize that because chlorine ac- tivation depends exponentially on water vapor and temperature, and in turn that the forcing of climate may well control the convective injec- tion of water into the lower stratosphere, the idea that ozone “recovery” is in sight because we have controlled chlorofluorocarbons and halon release is a potential misjudgment.
I thought spores are like sperm, they are needed to produce seeds... or am I wrong?
The lifecycle of ferns is a bit exotic and familiar.
It's classified as alternating between two generations, the one which produces the familiar large plant, and one that produces tiny plants.
It's something like "sexual reproduction with extra steps".
The fern chops its genome in half and produces spores with these haploid genetics. The spores grow into tiny plants (< 1 cm) which grow leaves and roots and then produce the sperm and/or eggs (the sperm actually swims to the egg!) which fertilized, grow into a new familiar fern.
In flowering plants, seeds are the result of fertilization which happens in the plant, they're bigger, contain food, and protective shells. The living cells which carry life are hidden inside. Pollen is a bit like a spore in that it's tiny and contains haploid genes, but still I'm guessing that process of reproduction is considerably more durable to increased UV.
But it's a cool paper. It would be interesting to see if they can find more instances of this sort of damage over various, widely space geographic areas. And especially in other species/other external signs of UV damage.
Even though they do analysis to try to eliminate other possible explanations, I'm not sure I'm super on board with immediately accepting the UV/ozone explanation whole sale. I always like to see bets hedged with "lends further evidence to support...." language.
I'd also love to hear from anyone with domain knowledge that might be able to add their perspective on the paper.
I'm interested in it because suntans seem so much worse now than in the past, where people didn't have access to suncream, yet still spent lots of time outside.
"I got used to it by spending my whole life outside" doesn't seem to fully explain it.
As an aside, don't get misled by nutters talking about ground level UVC levels. They don't know what they're talking about and are citing people who don't know how to use their UV-C meters (which are sensitive at wavelengths other than UVC and therefore require extensive filtering).
Further edit: I should mention total solar irradiance has remained relatively consistent over time (and continues to). I bring up these things because I've talked to some nutty people about this stuff in the past and those are common stepping off points into la-la land.
It should be noted that the 11-year solar cycle is much stronger in the shorter wavelengths, especially below 200nm. Since that is absorbed in the ozone layer there is a change of up to 2K max in the stratopause (~50km). It doesn't really appear to propagate down, and is rather on the level of a scientific curiosity, but still. [0] (Longer-term changes than the 11-year oscillation seem to be much lower, but this is hard to determine.)
[0] https://pubs.giss.nasa.gov/abs/gr08900n.html
To the parent post:
If you want to have information about UV at ground level you can look at proxy data. [1][2][3] Of course there are some complications with that as always though, and it's not that easy to interpret. But it looks like while there is variation it is mainly along the 11-year cycle. (I can't say much about the strength of the change on ground level without further reading. It's in the low percent range on top of the atmosphere, but almost all of that will be stopped in the ozone layer.)
[1] https://pubs.rsc.org/en/content/articlelanding/2009/PP/b9045...
[2] https://www.tandfonline.com/doi/abs/10.1080/0143116050007705...
[3] https://nph.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1469-...
Considering the issue of suntans, I think looking at the clothes people wear is more relevant to the question to be honest.
But a solar powered ozone generating ion wind propelled plane perpetually flying high up there certainly sounds cool.
It could also act as a communications relay.
What if we reverse the polarity on the main deflector dish.. I mean emitter wire?
> The effect is not directly dependent on electrical polarity, as the ions may be positively or negatively charged. Reversing the polarity of the electrodes does not alter the direction of motion, as it also reverses the polarity of the ions to match. Thrust is produced in the same direction, either way. For positive emitter polarity, nitrogen ions are the main charge carriers, while for negative polarity, oxygen ions are the main carriers and ozone production is higher.[citation needed]
https://en.wikipedia.org/wiki/Ion-propelled_aircraft
(also, I just used "reverse the polarity" unironically. I can check that off my bucket list)
Sure, if you wanna take my suggestion of nuclear-powered shock-zeppelins seriously... (loving the conversation my ridiculous idea inspired)
Now I'm curious what the energy efficiency of this process is.
I wonder if the rarefaction at that altitude makes it easier or more challenging.
2) Make a Solar Impulse kind of planes that basically deposit excess power in sparkgaps
3) Ozone
I suspect the ozone layer is not our biggest problem with the warming though.
That reminds me of the Simpsons episode where they bring in a serious of increasingly more absurd animals to deal with a small invasive species they find.
"But-"
"ONCE AND FOR ALL!"