Inverse Underwater Hockey Sticks?

From the University of Toronto,  Underwater ‘tree rings’

Calcite crusts of arctic algae record 650 years of sea ice change

Caption: This alga can be found in coastal regions of the North Atlantic, North Pacific and Arctic Ocean, where it can live for hundreds of years. Credit: Nick Caloyianus

Almost 650 years of annual change in sea-ice cover can been seen in the calcite crust growth layers of seafloor algae, says a new study from the University of Toronto Mississauga (UTM).

“This is the first time coralline algae have been used to track changes in Arctic sea ice,” says Jochen Halfar, an associate professor in UTM’s Department of Chemical and Physical Sciences. “We found the algal record shows a dramatic decrease in ice cover over the last 150 years.”

With colleagues from the Smithsonian Institution, Germany and Newfoundland, Halfar collected and analyzed samples of the alga Clathromorphum compactum. This long-lived plant species forms thick rock-like calcite crusts on the seafloor in shallow waters 15 to 17 metres deep. It is widely distributed in the Arctic and sub-Arctic Oceans.

Divers retrieved the specimens from near-freezing seawater during several research cruises led by Walter Adey from the Smithsonian.

The algae’s growth rates depend on the temperature of the water and the light they receive. As snow-covered sea ice accumulates on the water over the algae, it turns the sea floor dark and cold, stopping the plants’ growth. When the sea ice melts in the warm months, the algae resume growing their calcified crusts.

This continuous cycle of dormancy and growth results in visible layers that can be used to determine the length of time the algae were able to grow each year during the ice-free season.

“It’s the same principle as using rings to determine a tree’s age and the levels of precipitation,” says Halfar. “In addition to ring counting, we used radiocarbon dating to confirm the age of the algal layers.”

After cutting and polishing the algae, Halfar used a specialized microscope to take thousands of images of each sample. The images were combined to give a complete overview of the fist-sized specimens.

IMAGE: This is a diver dislodging coralline red algal crust from rock surface using hammer and chisel while enduring the near-freezing water temperatures of the Labrador Sea.

Click here for more information.

Halfar corroborated the length of the algal growth periods through the magnesium levels preserved in each growth layer. The amount of magnesium is dependent on both the light reaching the algae and the temperature of the sea water. Longer periods of open and warm water result in a higher amount of algal magnesium.

During the Little Ice Age, a period of global cooling that lasted from the mid-1500s to the mid-1800s, the algae’s annual growth increments were as narrow as 30 microns due to the extensive sea-ice cover, Halfar says. However, since 1850, the thickness of the algae’s growth increments have more than doubled, bearing witness to an unprecedented decline in sea ice coverage that has accelerated in recent decades.

Halfar says the coralline algae represent not only a new method for climate reconstruction, but are vital to extending knowledge of the climate record back in time to permit more accurate modeling of future climate change.

Currently, observational information about annual changes in the Earth’s temperature and climate go back 150 years. Reliable information about sea-ice coverage comes from satellites and dates back only to the late 1970s.

“In the north, there is nothing in the shallow oceans that tells us about climate, water temperature or sea ice coverage on an annual basis,” says Halfar. “These algae, which live over a thousand years, can now provide us with that information.”

###

The research, which was published in the Proceedings of the National Academy of Sciences, was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and Ecological Systems Technology.

###

here is the paper:

Arctic sea-ice decline archived by multicentury annual-resolution record from crustose coralline algal proxy, www.pnas.org/cgi/doi/10.1073/pnas.1313775110

They claim:

Significance

The most concerning example of ongoing climate change is the rapid Arctic sea-ice retreat. While just a few years ago ice-free Arctic summers were expected by the end of this century, current models predict this to happen by 2030. This shows that our understanding of rapid changes in the cryosphere is limited, which is largely due to a lack of long-term observations. Newly discovered long-lived algae growing on the Arctic seafloor and forming tree-ring–like growth bands in a hard, calcified crust have recorded centuries of sea-ice history. The algae show that, while fast short-term changes have occurred in the past, the 20th century exhibited the lowest sea-ice cover in the past 646 years.

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milodonharlani

Great to have some actual climate science practiced & published now & then.
As expected, the Little Ice Age had already begun by the 1360s, & Arctic ice cover has decreased during the past 150 years, as climate recovered from the LIA, which ended around 1860, after double bottoming during the sunspot Minima of Maunder c. 1645-1715 & Dalton c. 1790-1830.
Just the normal fluctuations of the Holocene, although with a disturbing longer-term (millennial scale) downtrend.

The findings are in agreement with the world emerging from the LIA in the mid 19th century, leaving the 20th century as the only one during that time to be free of the effects of the LIA.

John

Once again, someone tell Michael Mann that the Little Ice Age really existed.
Too bad the mainstream media, when the pick up on a study like this, refuse to examine how it relates to the iconic hockey stick.

TomRude

As usual all this is behind paywall. Thus the conclusions cannot be verified, in particular the arctic is vast and where in the Arctic is paramount to drwaing conclusions on atmopshere, sea ice and climate.

Janice Moore

A bona fide question from a non-scientist:
Re: “Longer periods of open and warm water result in a higher amount of algal magnesium.” (emphasis mine)
How do they know that the controlling variable is not the temperature of the water? How do they know that sea ice extent (i.e., amount of light) is a significant causation?
Isn’t a parallel (and erroneous) assumption commonly made about the controlling cause of tree ring width?
In other words….
How does this study prove ANYTHING?

pokerguy

“While just a few years ago ice-free Arctic summers were expected by the end of this century, current models predict this to happen by 2030.”
🙂

milodonharlani

pokerguy says:
November 18, 2013 at 6:07 pm
The authors probably know this is garbage, but made the obligatory obeisance to the One True Gas in order to get published under our Neo-Lysenkoist anti-science regime.

Janice Moore

Well, I guess I asked such a stupid question it wasn’t worth addressing. Sigh. What would a better question be? …… Is there a teacher in the house??
@ Poker Guy — heh. “… models predict ” tells me, at least, to be highly skeptical of this paper. It reeks of the Cult of Climatology’s spew. The faux science du jour, no doubt.

milodonharlani

Janice Moore says:
November 18, 2013 at 6:03 pm
To answer a question with a question:
You are aware are you not that most algae are photosynthetic, ie they use sunlight to make their own food?

Steve from Rockwood

“2012 exhibited the lowest Arctic summer sea-ice cover in historic times.”
If they are referring to the satellite record I’m not impressed.

lowercasefred

Q: How do they know the decreased ice cover is the result of climate warming instead of soot?
A: They don’t.

milodonharlani

Steve from Rockwood says:
November 18, 2013 at 6:39 pm
In consensus climate science, “unprecedented in history” means since 1979. Since anything less than 30 years at absolute minimum is weather, not climate, that gives us a record of observations on 1.13 climate units out of 150,000,000 such climate units. More than enough for post-modern climate science to make policy recommendations affecting the lives of seven going on eight billion people. Of course if the consensus, settled climate scientivists have their way seven going on one billion would be better, as long as they’re among the one out of seven saved by neo-Calvinist grace of superior election.

Chuck Nolan

pokerguy says:
November 18, 2013 at 6:07 pm
“While just a few years ago ice-free Arctic summers were expected by the end of this century, current models predict this to happen by 2030.”
🙂
—————————————-
I saw that too, they forgot their /sarc tag
cn

Janice Moore

Dear Milodon Harlani,
Thank you for your reply. Telling the student to take the basic premises and reason it out for herself is good didactics. Good for you to encourage scholarship. I’ll try to figure out the warmth vs. light problem and how the paper’s assertions prove ANYTHING about causes of global climate myself. Until then, I’ll just have to take it on your (and others’) authority alone that this paper is a good one. I was wrong to ask for free tutoring, here.
I hope that you have many lovely hours of enjoyment playing in the woodwind section (clarinet? oboe? bassoon?).
Take care.
Disappointed but grateful,
Janice

milodonharlani

Janice Moore says:
November 18, 2013 at 7:00 pm
Don’t know why you’re disappointed.
I’d have thought the relevance of light to the growth of algae was obvious, but you’re none the less welcome.
I hope the information will encourage you to study biology, in which case you’ll realize that the anti-scientific paid lying pseudo-philosophers from the Discovery Institute whose mendacious videos you keep linking in lieu of actual learning & thought on your part are not only not biologists but blasphemous imps of Satan who have led you astray on the path to eternal damnation, since their image of God is of a cruel, sadistic, incompetent, deceptive liar.

Janice Moore

Dear Milodon Harlani,
Have you ever watched the videos I linked? Every time I ask that, you do not answer. Did you think I did not notice? I think that, if you look into it, you will find that Dr. Stephen Meyer’s and Dr. David Berlinski’s credentials provide an excellent basis for their scholarship.
You accuse me of not learning, but you refuse to watch the lectures I posted (I only re-posted them because from your remarks, it was pretty clear that you had not watched them). How do you know that they are not well-reasoned and persuasive without listening to them?
I take great hope from your snarling response! Why? Because only one who senses that he is in danger lashes out like that. Watch out, Mr. Harlani — you are being prayed for and I believe God is going to reveal the truth to you!
And I still love (agape) you. #(:))
Yours,
Janice
P.S. How’s the clarinet (or oboe or bassoon) playing going? I hope it gives you much joy.

milodonharlani

Janice Moore says:
November 18, 2013 at 7:38 pm
I don’t need to look into it, Janice Moore, because I’m thoroughly familiar with their total lack of credentials. They have practically no knowledge of biology, except just enough to know that they are lying shamelessly, but they don’t care, because they’re paid to hoodwink suckers. I’ve listened to their pack of lies for over a decade. To call their mendacity “scholarship” is the deepest possible insult to every scholar who has ever lived.
I don’t refuse to listen to your pathetic videos. I’ve heard them & talked to them in person. They’re paid liars, plain & simple.
I’m not the least bit in danger. It is you whose soul is in mortal danger. Your heroes are liars against the God of creation, Janice Moore. I pray you learn that before it’s too late.
God has revealed Himself to me through His creation. His Works in creating the universe(s) take precedence over your satanic, bibliolatrous, blasphemous interpretation of His Word. Wake up! You’ve been sold a bill of dangerous goods. Learn actual science instead of false religion. Worship the Creator & not a book written by men (& maybe one woman) trying to grasp the Infinite.
BTW, please don’t try to tell me what an English neologism from corrupted Koine Greek roots “means”. Greek “agape”, as dragooned into biblical English in the 17th to 19th centuries is cognate with English “agape”, as in slack-jawed. I’ll let you figure out how that could be. The hint is that it has to do with an early Christian ceremony.
Like most creationists, you have almost as much to learn about science as about the Bible, about which you need to unlearn almost everything, your satanic tutors having intentionally misled you.

Manfred

Another study matching well with either the sun or black carbon and not so well with CO2 as the main drivers in the Arctic.

Katherine

Almost 650 years of annual change in sea-ice cover can been seen in the calcite crust growth layers of seafloor algae, says a new study from the University of Toronto Mississauga (UTM).
[…]
During the Little Ice Age, a period of global cooling that lasted from the mid-1500s to the mid-1800s, the algae’s annual growth increments were as narrow as 30 microns due to the extensive sea-ice cover, Halfar says. However, since 1850, the thickness of the algae’s growth increments have more than doubled, bearing witness to an unprecedented decline in sea ice coverage that has accelerated in recent decades.

Their proxy covers less than 650 years and they have the gall to use “unprecedented”?! What idiots.

davidmhoffer

“It’s the same principle as using rings to determine a tree’s age and the levels of precipitation,” says Halfar.
Wow, how’d that get past the censors? Tree rings respond to precipitation? Mann must be scurrying around in circles screaming “off with his head!”

milodonharlani

Katherine says:
November 18, 2013 at 7:58 pm
Unprecedented is another obligatory buzzword. Please cut researchers some slack who try to fit real science into the cracks of the CACA paradigm. If unprecedented means since 1360, they might be right. If since AD 1060 or 60 BC or 1060 BC or 2060 BC or 3060 BC or earlier, then OK, precedented. CACA corrupted quackademia is a bitch right now.
But maybe you’re a scientist with the integrity not to play that game & still survive. If so, & you can still get published so as not to perish, then more power to you! You go, girl!

Mushroom George

Recently, sea ice area increases in Antarctica seem to balance out most of the sea ice decreases in Uncle arctica. I would like to see algal growth rates from both poles compared.

TRM

Okay good start. Now about going back further, you know to that medieval warm period. I wonder why they chose the starting date that they did? Hmmm?
” lowercasefred says:November 18, 2013 at 6:45 pm
Q: How do they know the decreased ice cover is the result of climate warming instead of soot?
A: They don’t.”
Good point. The industrial revolution has put a lot of soot up there especially lately. It would be interesting to see if there is a correlation between their data and soot.

davidmhoffer

http://www.pnas.org/content/suppl/2013/11/14/1313775110.DCSupplemental/pnas.201313775SI.pdf
supporting data
they seem to have only six samples, of which only two go back further than 1800. The other two have a glaring discontinuity about 1850. Will be interesting to see if SteveM decides to pick this one apart.

milodonharlani

Mushroom George says:
November 18, 2013 at 8:07 pm
Excellent point.
Of course the Antarctic & Arctic are very different environments, but your allusion to ice algae in the Antarctic reminds me of one of my favorite species, ie Antarctic krill, one of the animals whose biomass challenges the human. Besides phytoplankton, one of their main food sources is, wait for it, you guessed it…ice algae. Here’s a tight shot of the tiny krill in action, grazing on the ice algae:
http://en.wikipedia.org/wiki/File:Krillicekils.jpg
Needless to say, the tiny krill feed the biggest animals & organisms ever to have evolved, baleen whales. By D. H. Lawrence, edited for biological correctness:
“Whales Weep Not!
They say the sea is cold, but the sea contains
the hottest blood of all, and the wildest, the most urgent.
All the whales in the wider deeps, hot are they, as they urge
on and on, and dive beneath the icebergs.
The right whales, the sperm-whales, … the killers
there they blow, there they blow, hot wild white breath out of
the sea!…”

Dr. Bob

Is there any data supporting the hypothesis that growth rings are directly proportional to temperature, sunlight penetration or maybe perhaps dissolved CO2. Unless you can prove that growth rings are proportional in width to some factor, it is hard to say anything about these data. It seems to me that people take for granted proportionality when they don’t have proof of concept.

milodonharlani

Dr. Bob says:
November 18, 2013 at 8:23 pm
As with tree rings, many factors go into annual growth rates in algae, making them in both cases problematic as paleoclimatic indicators. However, for under ice algae, sunlight is critical, so I’m OK with this proxy, subject to caveats.

dp

How many more coincidental events beginning with the end of the LIA do we need to bury the CAGW hoax? That was the end of the most recent glacial expansion and so glaciers have been receding, ice all over the planet had passed the zenith and there is melt to the pre-LIA level. The end of LIA’s are going to do things like this. Warming? Of course there will be warming – that was going on even before the LIA because the BIA (big ice age) had ended. What we’re seeing today is not climate change – it is the response to the most recent climate change which happened quite a long time ago when the LIA began and before that the beginning of the interglacial period.

Brian H

Weasel-words again.

the 20th century exhibited the lowest sea-ice cover in the past 646 years.

Yup, that would be the peak and plateau of the post-LIA Warming, all right. Period.

davidmhoffer

As little as 3 years ago the same researcher was singing a different tune:
Large positive changes in algal growth anomalies were also present in the 1920s and 1930s, indicating that the impact of a concurrent large-scale regime shift throughout the North Atlantic was more strongly felt in the subarctic Northwestern Atlantic than previously thought, and may have even exceeded the 1990s event with respect to the magnitude of the warming.
http://www.sciencedirect.com/science/article/pii/S003101821000218X

milodonharlani

davidmhoffer says:
November 18, 2013 at 8:44 pm
The two perspectives might not be mutually exclusive. In the new paper, the author(s) look at centennial scale changes. The fact that there was less ice in the 1930s than 1990s doesn’t negate the finding of less ice in the 20th century than 19th.

The Watcher

[Snip. Read the site Policy. Labeling others as ‘denialists’ is not allowed here. It is a mindless pejorative that takes the place of thinking. —mod.]
The unbridled skepticism here–based on cherry-picking the incredible reports of a few so-called scientists with credentials practically written on toilet paper (and far more easily shredded)–reminds me of a preteen bullying and boasting session in a schoolyard. 
If you want to pick apart scientific work, bring ACTUAL SCIENCE to the game and leave out the name-calling BS that gives NOTHING for real scientists to do but guffaw at. The childish games most you offer in lieu of facts remind me of nothing so much as adolescent boys’ boasting/gloating/bullying sessions about nonexistent sluts and orgies they wish they really experienced. 
The cult of the Flying Spaghetti Monster is alive and well in Skeptic Land.
“A mind is a terrible thing to waste,” and i feel terrible having wasted mine watching the waste pile up on this wasteland of a website. Don’t you all feel just sooooo useless believing in tattered shreds of hope made of such UTTER feces??? I mean, REALLY, people!
The scientists you blindly believe in are hoaxers whose work is so lame it can’t be published in peer-reviewed journals, and– certainly in the case of Patrick Michaels, a researcher whose bias is completely transparent in the Big-Oil-tilted funding he enriches himself on–TAINTED and SUSPECT. Their work seems made up wholesale out of hodge-podge bits of dire fear, wishful thinking and rag-tag nonsequitur-like pools of unrelated facts. It almost comprises its own sub-genre of fiction.
PLEASE just GIVE UP the insane religion and START TRUSTING MAINSTREAM SCIENCE. Unless you like to be seen (figuratively, of course) riding dinosaurs in the oxymoronically named Creation Science Museum.
[Note: Use one screen name only, please, per site rules. Pick between ‘Tshane3000’ and ‘the watcher’. Thanx, ~mod.]

Ken L.

As a non scientist, who nonetheless has a vague understanding of statistics, how does the science community manage to ensure that using proxies does not inadvertently miss other variables that might render the correlations spurious – especially ones in the past that cannot be observed or accounted for? I can see how proxies are useful, but can they be selected as a method to test and devise hypotheses? It is just difficult for me to get hold of.

davidmhoffer

Congrats Watcher.
One sentence complaining about ad hominem attacks accompanied by 7 paragraphs of ad hominem attacks.

milodonharlani

davidmhoffer says:
November 18, 2013 at 9:14 pm
LOL!
I know, it’s one of those “Where to begin” problems.

Ken L.

The Watcher:
“If you want to pick apart scientific work, bring ACTUAL SCIENCE to the game and leave out the NAME CALLING BS that gives NOTHING for real scientists to do but guffaw at.”
As in your post, sir?
The Watcher:
“PLEASE just GIVE UP the insane religion and START TRUSTING MAINSTREAM SCIENCE.”
I distrust alarmist science, largely because of persons who post material such as you have. While not a scientist myself( there are a great MANY who comment here, who are), I’ve taken enough math and science in school, read enough, and thought for myself enough to recognize the pseudo – religious nonsense that is propaganda masquerading – as science. It’s obvious that you would love there to be a technocracy, with you or your scientific papal wannabes handing out the truth to be accepted without question.
If you are spoofing(and one has to be suspicious), good job. You got me! If not, are you one of Al Gore’s internet bots?

davidmhoffer

milodonharlani says:
November 18, 2013 at 8:48 pm
davidmhoffer says:
November 18, 2013 at 8:44 pm
The two perspectives might not be mutually exclusive.
>>>>>>>>>>>>>>>>>.
Fair enough, but I was focused on this statement from the current round:
However, since 1850, the thickness of the algae’s growth increments have more than doubled, bearing witness to an unprecedented decline in sea ice coverage that has accelerated in recent decades.
I interpret “recent decades” to be the last two or three, not the last 10.

Jquip

@milodon: “Like most creationists, you have almost as much to learn about science as about …”
Any theory is the same as any other theory. I’ve as much problem with any of them as I do with non-Euclidean geometry. The only relevant showstopper is when you attempt to apply it to the physical world, and the physical world disagrees with you.
“As with tree rings, many factors go into annual growth rates in algae,…”
This is the critical issue as, like treemometers, it is warm and open and magnesium levels. I assume for the most part that we can treat mag as constant and ignore it. If so then it passes an impromptu smell test as you don’t get ice unless it’s cold, and if you have ice you lack light. Not terribly impressed with it however. It repeats what’s commonly accepted and avoids the MWP as such series commonly do. If they’d looked at the latter at all, I’d be inclined to spend time with the paper.

Eugene WR Gallun

To The Watcher
I am guessing that you would consider Michael Mann’s hockey stick to be mainstream science.
But for the record, tell me — what is your opinion of Michael Mann and his hockey stick? State clearly the opinion you hold about him and his hockey stick.
Eugene WR Gallun

FrankK

“While just a few years ago ice-free Arctic summers were expected by the end of this century, current models predict this to happen by 2030. This shows that our understanding of rapid changes in the cryosphere is limited, which is largely due to a lack of long-term observations.”
Well, its an interesting and novel study and requires further verification. Skeptics and many climate scientists acknowledge warming from the Little Ice Age. So what? Doesn’t prove warming by CO2 does it ?
What I find disingenuous is the statement that “While just a few years ago ice-free Arctic summers were expected by the end of this century current models predict this to happen by 2030” Really? Its not that long ago Anthony Watts was running a count on the claim that it would be ice-free in this year’s Arctic summer. Moving the goal posts seems to be the strategy all too often in these research papers beyond the author’s tenure time period. And peeeleese, the models are junk leave them out of it.

milodonharlani

Jquip says:
November 18, 2013 at 9:35 pm
My brother, not all “theories” are created equal, as I’m sure you’d agree.
I too am not terribly impressed, but it is IMO a more or less honest attempt to conduct actual science, so should be welcomed, however skeptical you or I may be. Either the study stands up to skeptical analysis or it doesn’t. But at least it puts an thesis out there for you, me & various & sundry to attack, as science would have it.

“…. in particular the arctic is vast and where in the Arctic is paramount to drwaing conclusions on atmopshere, sea ice and climate.”
Vast? Everything is relative, but to claim that Arctic is vast is a bit far? 80N-90N is about 0.76%, less than 1%, of the World.
70N-80N is about 2.2% of the world
In comparison EQUATOR to 20N is about 17.1% of the World.
70N-NORTPOLE(90N) is about 3% of the World. If 3% is vast, what is 17.1%?

HGW xx/7

The Watcher (aka I Have a Really Deep and Mysterious Name and, Thereby, Am to Be Taken Seriously!!!) says:
I won’t bother quoting any of his ‘post’. Amongst the misspellings, complete absence of the evidence he wails for, ad hominem, projection AND BIG BOLD LETTERS, there’s a frightened little Prius driver who is upset that more people didn’t die in this disaster or that.
Worry not, oh Bearer of the ‘Coexist’ and ‘Wage Peace’ Stickers. Someday, you will stumble upon the readily available information on this site, actual hard data, provided by the very agencies and sources you uphold as mainstream and unassailable, the ones we can’t question and quell the need for any discussion.
Hmmm…actually, blindly screaming and pointing to an authority, demanding adherence… Gosh, that sounds an awful lot like… Nah! 😉 You’re too smart to fall for religion, aren’t you, THE WATCHER!?!!?!1!!! (That’s supposed to be said with dubstep screaming in the background, by the way.)

F. Ross

@ Watcher:
May I suggest that you read some of the commentary on this website by Dr.R. G. Brown, a physicist at Duke University –none so far on this article but he posts on WUWT occasionally.
Who knows, you might even learn something, but then that is up to you.

AndyG55

“The Watcher”..
because its all you are capable of…

Mark Fawcett

As with all proxy studies, surely the major potential stumbling block is that of multiple variables that can affect the main metric and how, or indeed whether, you can legitimately address, reduce or remove them.
In the case of tree ring widths (the metric) it’s sunlight, precipitation, disease, population-density, temperature (the variables) when you’re attempting to find a link twixt only width and temperature (you obviously can’t IMHO).
For this latest study there’s another host of potential variables that spring to mind: sunlight, disease, water temperature, salinity, alkalinity and predation (that’s little fishies eating the stuff). How can you possibly remove, reduce or account for all of these other variables when trying to show a definitive link between sunlight and growth?
Cheers
Mark

Mike M

Doesn’t increased algae correlate to a greater abundance of other sea life ultimately leading up the food chain to polar bear food, (seals)? Food supply is usually found to be the strongest determinant of species survival – not climate by itself.

dp

Mr. Watcher – I looked for science in your post and came up empty. Might you have a link to actual and effective rebuttal material to the notion that the leftist think pro alarmist catastrophist meme propaganda has other than clay for a foundation? Tickled to learn more. Show us what you have – don’t just dine and dash on us, yours always,…

Jquip

milodon: ” But at least it puts an thesis out there for you, me & various & sundry to attack, as science would have it.”
Bingo. If it fails, it still makes good for fiction. If it fails to fails it brings different considerations to the table. Which is, at the least, useful for highlighting our unstated prior assumptions.

juan slayton

Mark Fawcett: …surely the major potential stumbling block is that of multiple variables that can affect the main metric…
Nice list, that can readily be extended. Comes to mind that CO2 itself is one that should be considered. If I understand correctly Graybill and Idso were originally investigating the CO2 / ring width correlation 20 years ago.