From the University of Toronto, Underwater ‘tree rings’
Calcite crusts of arctic algae record 650 years of sea ice change
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.
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  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.
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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.
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here is the paper:
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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Graphs and other stuff available in S.I. from PNAS:
http://www.pnas.org/content/suppl/2013/11/14/1313775110.DCSupplemental
I’d like a peek behind the paywall here. It sounds like this paper confirms the LIA and that the warm period started already 150 years ago. Probably there’s little in the paper that would surprise an AGW skeptic, but I’m sure the #MannMachine will still market this in the predictable ways…
If You actually look at the data they only seem to have three samples, not all that similar to each other and only one going back before 1800, but it is true that all three seem to indicate warmer conditions post c. 1850. However in all three samples the 1930s-1940s come out as warmer than the last few decades, there most definitely is no trace of any “hockey stick”.
The data is here (the tnree left-hand graphs at the bottom of p. 2):
http://www.pnas.org/content/suppl/2013/11/14/1313775110.DCSupplemental/pnas.201313775SI.pdf
Note that the authors aren’t actually lying, there is evidence of less sea ice in “recent decades” (if recent is understood as post-1850), it is unprecedented (if unprecedented means post 1800, possibly post 1360) and for the rest they are just referring to other peoples models.
In all this is interesting research, unfortunately marred by a transparent effort to toe the party line.
What does The Watcher watch? Where can be found the Mainstream Science that he urges us to trust? Methinks he watches his telescreen. Big Brother also watches.
Dutch and Irish scientists have discovered that in a computer simulation of the climate a spontaneous mini-ice age has broken out.
http://www.telegraaf.nl/binnenland/22068601/__Spontane_ijstijd_in_computermodel__.html
According to the researchers of the KNMI and the UK’s National Oceanography Centre, this computer version of the ice age is a sign that there are “unexpected elements in the climate system.”
In the computer model that simulates the climate it became suddenly one to two degrees colder.
http://www.pnas.org/content/early/2013/11/12/1304912110.abstract
So at last we’re getting some facts to support (or not) the Chicken Little panicking about Arctic sea ice and we find that while it has been on a decline (we knew that) this decline has been going since the second half of the 19th century and not just since 1979.
How are they going to spin that one, I wonder?
This is a very interesting paper and that collection and analysis seems to be thorough and meticulously conducted.
However, I see one logical error that could notably affect the interpretations of the data.
Figure S1 in the SI (linked above) shows the temperature dependency that they find from looking at recent data from different regions with different average temperatures.
This has a distinctive downward curvature as temperature drops. The authors draw a straight line between the first two regions , which are below 52N and apparently _assume_ this reflects the temperature dependency of growth rate in largely ice free conditions.
Any deviation from this line is then attributed to a reduction in the length of time light gets to sea floor, hence is a proxy for ice coverage.
When I see just two points determining the straight line, I tick.
Most chemical reactions have a logarithmic relationship to temperature, roughly doubling with every 10K rise. It would seem that this should be taken into account rather than assuming a linear relationship as it appears that the authors do.
The linear fit is somewhat steeper than 10K per doubling between the two points and should curve in the opposite direction as the change from 200 to 100 would also span 10K
Since the past centuries were generally colder this will affect their long term modelling.
It look like a valuable dataset from which useful information can be derived.
milodonharlani says:
November 18, 2013 at 7:54 pm
“…”
Well, that’s a forceful and intriguing response! Can you give a hint where one can learn more of your views?
fig S1 excerpted from SI
http://climategrog.wordpress.com/?attachment_id=640
These are some of the worst set of comments I have ever seen on WUWT, even without the Watcher’s alarmist rant.
The LIA is generally seen as lasting from 1350 to 1850, so these ice algae indicate it was cooler and/or darker during this period – that is exactly what you would expect.
After 1850, the Earth warms up a little bit – about 0.7 degrees C to the present day – so today you would expect these algae to reflect warmer and/or brighter conditions than during the LIA.
All these algae are doing is demonstrating the reality of natural climate cycles, the great heresy of the alarmist cult.
Even the most extreme of alarmists do not believe man had much of an impact on climate prior to 1970, so even by their twisted standards of interpretation most of the warming (120 years) occurred before there was any impact from CO2.
In addition, if you look at the charts provided by tty, you will see the Arctic is indicated to have cooled and/or become darker since 1970.
Sigh……so much ado about nothing.
Thank you Mr. Miller, for answering, no doubt, unintentionally, and indirectly, my poorly phrased question about the usefulness and accuracy of proxies. Sometimes you don’t really know what to ask until you see the answer. Your brief analysis, is to me, an example of what proxies such as tree rings etc. are, it seems intuitively obvious to me, good for – describing and confirming cycles and trends, not coming up with comparisons in absolute measurements on a scale of precision when you look at the overal range of temperatures on the planet, that seems highly questionable.
Someone can most certainly correct me if I’m wrong.
Apologies for my response to The Watcher’s troll like exposition or ‘ rant’ as you put it.. It did nothing to raise the level of discourse, even if it made me feel better at the time. We should be mindful that Anthony opened up the comments section, knowing there was a risk,. and not abuse something he can take away if he chooses.
It says that data is deposited with NOAA National Climatic Data Center but does not give a precise source.
Anyone know exactly where?
Colonies of creatures living on the seabed for hundreds of years have been removed with a hammer and chisel to add weight to a discredited theory? Ecological vandalism and they say they are trying to protect the environment??
We had evidence that the Arctic had warmed over the last 150 years or so …
http://climate4you.com/images/GISP2%20TemperatureSince10700%20BP%20with%20CO2%20from%20EPICA%20DomeC.gif
… but science is all about checking things in different ways, so this study confirming it is a positive.
As the above climate4you.com graph shows, the recent warming could reasonably have been expected to occur as part of an inexact ~1000yr cycle, and it obviously isn’t driven by CO2. But then the latter is obvious from this study too, because the warming was found to have been in progress for over 150 years.
So why can’t these people just state the obvious, instead of making fatuous statements like “the 20th century exhibited the lowest sea-ice cover in the past 646 years”. Note : (a) The 20thC includes the 1930s. (b) The last 646 years do not cover the MWP. (c) Their data is only from within the Arctic and the Antarctic has recently set satellite-era sea-ice highs.
I thought the ice cores already explained everything. Now we admit we don’t know? However algae will supply the answers?
Sorry, but I have trouble trusting algae. Didn’t algae produce a movie called “The Inconvenient Truth?” (Al G……get it? Hyuk hyuk hyuk.)
All joking aside, I think it is rather brave of the fellow to go swimming in water that cold, and good to gather any sort of real data in the real world, rather than playing video games with virtual data at computers.
Now we will have to see how the conclusions stand up to real scrutiny.
It would be good if they could find some of this algae old enough to tell us how warm the waters were when the Viking were growing barley in Greenland, a thousand years ago.
One of the 3 samples has the lowest ring width around 1860 (signalling the highest sea ice coverage).
While another has the highest ring width data around 1860 (signalling the lowest sea ice coverage).
I think Halfar needs a lot more samples to prove anything with this proxy. He has been using the methodology in many places around the world but you need many samples in any one location and they should have a consistent signal as well, not opposite signals.
The study is interesting. It is clear that Mann is wrong from this study. But no one in academia is willing to point this out.
The study’s genuflection to AGW is disturbing. No study these days seems able to stand on its own without a bowing down to the CO2 obsession.
Notice how the ‘ice free’ prophecy is now back to 2030. It had of course infamously and falsely got too close- now. Then it was moved way out, to 2075 or so. Now it is creeping back down to 2030. This is so similar to the rapture myth, that peaked out recently at 1975, with Jehovah’s Witnesses and Hal Lindsey both naming the mid-1970’s as the time for the great tribulation, then admitting by the early 1980’s it might not be so, and now pulling back in the time for the great tribulation as memories fade.
Greg Goodman says:
November 19, 2013 at 3:11 am
It says that data is deposited with NOAA National Climatic Data Center but does not give a precise source.
Anyone know exactly where?
—————————-
It doesn’t appear to be up yet.
There are 3 other studies from other years in which Halfar is the lead author and 3 others where he is a co-author. Go to Halfar in this index to see the ones where he is the lead author.
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/
This item requires a subscription to Proceedings of the National Academy of Sciences.
You may access this article (from the computer you are currently using) for 2 days for US$10.00.
The SI is available here for free …
http://www.pnas.org/content/suppl/2013/11/14/1313775110.DCSupplemental/pnas.201313775SI.pdf
‘The Watcher’ says:
“PLEASE just GIVE UP the insane religion and START TRUSTING MAINSTREAM SCIENCE.”
In essence that is what 100 mainstream scientists wrote to Albert Einstein.
Who ended up being right? Einstein? Or the ‘mainstream’?
Watcher:
Peer reviewed literature. As shown by your comment, anyone is allowed to comment on this site. Thus, anyone is entitled to review the pieces written as long as they do it in an open and transparent way. As near as I can tell, any “mainstream climate scientist” can review any post here. Frequently, many scientists review a post on this site. The reviewing process on this site is a bit rough and tumble, but open debate is the enduring characteristic. Anyone is allowed to see the reviews and make judgements about the pieces and the reviews themselves.
The closed journals with limited and unknown reviewers where “mainstream scientists” publish are antiquated artifacts of pre-internet ways of doing things. Think Encyclopedia Britanica as compared to Wikipedia. E.B. Is gone. And people make judgements about what to believe in Wikipedia.
Peer reviewed literature as a concept is out of date. In many fields and for many papers, it suffers from group think and slipshod or unknown reviews. In the case of climate science, it appears if the level of understanding of statistics by the group of reviewers at the “peer reviewed journals” is quite low and they miss statistical errors with great frequency. This is a significant problem with the process and leads to bad science.
Appeals to peer reviewed literature don’t cut it with me any more.
Silence about the rest of your comment does not imply [that] I agree with any of it.
milodonharlani says:
November 18, 2013 at 7:21 pm
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.
I would not want to get into this heated argument, but as I have spent a long time looking at research papers that gloss over base assumptions, I asked the same question as Janice Moore on which was it that was the controlling variable for growth of coralline algae – warmth or light.
So a quick look at various papers on the internet showed that there are multiple species of coralline algae (hardly a surprise) that compete in their natural habitats. Some of these species grow under rocks to avoid light that is ‘too strong’. In consequence this study may be showing the levels of growth of different competing algae of the one family: once reduced to calcite it will be impossible to tell which species of coralline algae formed the layer, I would also expect that there are effects from warmth that may also be counter intuitive to an underwater climatologist and other effects from nutrients and salinity changes..
Until this study can normalize for species variance then it really cannot show anything apart from apparent increase in algal growth that appears to have a correlation to the increase in bottom water temperatures after little ice age – not necessarily a causal link. Claiming to know what the ice cover was is a step too far based on unproven assumptions.
To put things in perspective :
I don’t see anything in this article that isn’t already common knowledge.
“Unprecedented loss of ice” hasn’t resulted in any unprecedented rise in sea levels
Soot and CO2 levels have risen in parallel since 1850. Rises in soot seem to explain
why the Arctic is losing ice whilst the much larger (and more important) Antarctic is not,
a phenomenon that CO2 increases cannot explain. Any change in the Arctic but not the Antarctic
is a regional, not global, affair.
A touching article of faith that these folks use current AGW climate models to foresee the future, especially when they have failed so abysmally in the past, especially concerning sea ice.
Why can’t they just publish a paper saying this a tool, here are its capabilities and limits. Lets correlate the tool with modern satellite measurements for several decades and then decide if a wider study of arctic waters would result in a longer baseline and/or more confident results.
Then let some University PR weenie write the Global Warming BS for a magazine or a website.
Algae grows better w/more light & less ice-cover. Who knew? I’ll extrapolate & say phytoplankton in general grows better too. Prb’ly the entire food-chain benefits, as Jim Steele has posted about previously.
It’s much better than we thought.