Study rehabilitates climate models

Bern study rehabilitates climate models
Sampling of a sediment core from a floating platform. Credit: Oliver Heiri, University of Bern

With new methods of reconstruction, climate researchers in Bern have been able to demonstrate that some 9,000 to 5,000 years ago, the Mediterranean climate was considerably warmer than previous studies had suggested. Among other things, previous concerns regarding the reliability of climate models could thus be dispelled.

Climate reconstructions are necessary because reliable measurement data are only available for the last 150 years. For this reason, research on past climate change uses so-called 'proxies'. These are indicators with which it is possible to reconstruct temperatures in the past. A widespread reconstruction method examines pollen which is embedded in lake sediments. From the composition of this pollen, it is possible to determine the plant species which occurred at a particular location in the past – and since the temperatures that the individual species require are also known, it is possible to reconstruct the temperature conditions for the period in question.

It is on the analysis of pollen – including from silver fir trees in Italy – that the only previously available quantitative summer temperature reconstructions for the northern Mediterranean region were based on. These suggested that the mid-Holocene (9,000 to 5,000 years ago) had been an exceptionally cold period. However, it is also possible to examine past climate using models. In contrast to the pollen analyses, model-based simulations indicated that summer temperatures should have been warmer during this period.

This presented with a puzzle: why do the reconstructions of the summer temperatures for the northern Mediterranean region in the mid-Holocene period clearly contradict the results from the ? "The two results diverged so clearly", explains Oliver Heiri, a Paleoecologist and one of the authors of the Bern study, "that they made some of our colleagues question the reliability of climate models for regions such as the Mediterranean." Different research groups at the Oeschger Centre for Climate Change Research at the University of Bern have now been able to solve the puzzle, however. Their research has been published in the journal Nature Geosciences.

Bern study rehabilitates climate models
Remains of a midge larva. The distribution of these microfossils in lake sediments provides information on past temperatures. Credit: Oliver Heiri, University of Bern

The researchers at Bern demonstrate that the results from further methods of reconstruction agree very well with the climate models. Ultimately, the past distribution of important species of pollen-generating plants had not only been determined by temperature, but also by other factors such as moisture levels, early forms of agriculture and fire. If pollen from silver fir trees is discovered in the layers of sediment for example, this does not necessarily indicate that it was cold. This finding is based on an alternative method of reconstruction which Oliver Heiri and his colleagues applied to this time interval for the first time in the Mediterranean region. The researchers examined past shifts in the abundance of indicative groups of midges (Chironomidae) based on analyses of their fossils in sediment cores from two lakes in the Apennines.

Further researchers at Bern were then able to show that the climate conditions in the Apennines are representative for a large part of the northern Mediterranean region. They also demonstrated the plausibility of the new temperature reconstruction in terms of the results of the models. "It is only discussions between researchers from differing disciplines which enabled new hypotheses to be developed and examined in detail", explains Oliver Heiri, before highlighting that "the Oeschger Centre is predestined for this kind of collaboration."

The new findings on the past climate of the Mediterranean area do not mean, however, that pollen-based reconstructions should be questioned in general. Oliver Heiri emphasizes that the method remains useful in other geographical regions, and especially for other periods. "Our work clearly shows the importance of developing new methods for climate research though." The Paleoecologist explains that this enables existing knowledge to be examined and new research questions to be formulated.


Explore further

Decrypting 1,000 years of past climate history in Europe

More information: Stéphanie Samartin et al. Warm Mediterranean mid-Holocene summers inferred from fossil midge assemblages, Nature Geoscience (2017). DOI: 10.1038/NGEO2891
Journal information: Nature Geoscience

Provided by University of Bern
Citation: Study rehabilitates climate models (2017, February 7) retrieved 19 August 2019 from https://phys.org/news/2017-02-climate.html
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Feb 07, 2017
So, the temp proxies were wrong and the climate models are wrong. The fact that two wrongs didn't make a right caused concern ..."that they made some of our colleagues question the reliability of climate models for regions such as the Mediterranean."

Thus, they tweek the proxies.

Too bad that the climate models are still wrong.

Feb 07, 2017
"Climate reconstructions are necessary because reliable measurement data are only available for the last 150 years."

Apparently not. The author must not be aware that data collected during the past 150 years is never used "raw." Satellite data is subject to "adjustment," due to imperfect orbits and miscalibrated instruments. Sea surface temp data is too meager to be useful without extrapolation. Even data from land-based Stevenson boxes cannot be taken at face value, for a host of reasons including human error, urbanization, instrument failure. Data sets have been adjusted (revised) repeatedly. The current spate of "record high" temperatures is the conflated result of making the past seem cooler through data revision, plus a strong El Nino.

With respect to climate science, there is NO reliable raw data.


Feb 07, 2017
I myself can't wait for the next upward revision of the temp data where I live. Then this damn miserable Feb day can be turned into a balmy day before my lying eyes. Of course this is a short term effect only. As the further into the past we go the colder the revisions make it. By the time I retire it will need to be revised down again and then in fact I will have frozen to death.

Climate change truly can be deadly.

Feb 07, 2017
Oh, and the headline! It's wrong. "Previous studies," the original ones, correctly interpreted the data. It is the latest studies from the IPCC that are wrong. Recall that in the early '90s, a retreating glacier in the Alps revealed the body of a man who had died about 7,000 years ago. It had to be at least as warm then as now, n'est-ce pas? The Romans planted vineyards around York, England, back when they ran the place. It had to be at least as warm then as now, n'est-ce pas? The Vikings' plundering voyages and early explorations in search of a Northwest Passage were possible because, when climate is warm, storms are fewer and northern ice is melted. It had to be at least as warm then as now, n'est-ce pas?

Feb 07, 2017
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Feb 07, 2017
By the time the AGW Cult is done, they will put that other infamous cult; the Church, to shame in rewriting history just to propagate their dogma.

Feb 08, 2017
As the funding lines change in the next 4 years it will be very entertaining watch the AGW crowd throw each other under the bus. It's all about the money and although there will remain much private funding of AGW, the trump hit in the EPA and NOAA will be devastating to their pocketbook.

Look for the rats to start jumping ship sometime this fall.....I am already seeing it in some draft proposals.

Feb 08, 2017
By the time the AGW Cult is done, they will put that other infamous cult; the Church, to shame in rewriting history just to propagate their dogma.

Fortunately we back up our claims with real science, on the other hand, your airhead contributions discussed with your own socks above always leads to confusion and self doubt for yourself.

Feb 08, 2017
So, the temp proxies were wrong and the climate models are wrong. The fact that two wrongs didn't make a right caused concern ..."that they made some of our colleagues question the reliability of climate models for regions such as the Mediterranean."

Thus, they tweek the proxies.

Too bad that the climate models are still wrong.

FactsReallyMatter ? this must be an idiot, I don't see any facts in your lies.

Feb 08, 2017
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Feb 08, 2017
Fact is YOU are a coward for not caring about pollution, nor standing up to Facts and Reality, the bloated empires of the lying and deceitful will come crashing down sooner than you think

Feb 09, 2017
Geesh, I thought chicken little was a fictional character. Seems we have plenty of them on this site. I wonder, is this site based on fiction or fact? Fiction for the AGW cult it seems.

Feb 09, 2017
Don't worry Lot's of funny things in your thoughts everyday, we see them posted on the forum everyday... like the one here just now where you once more tried to lie, and instead (yet again) dumbed down you and your socks even lower than ever before:

https://phys.org/...ade.html

the fact is, you Didn't even know ph is a logs scale, yet You trie and Deny Scienctific Facts LOL

Feb 09, 2017
You believe that log means a cut tree flowing down a river. Your post certainly doesn't have anything to do with what I wrote.

But then again, all you have is belief. I'll stick with the facts, AGW is a cult, the models are completely wrong, and there will soon be much less wasted public funding researching the monster in the closet.

It would seem that you maybe qualify for a job a McD's, better hurry cause the robots are coming.

Feb 09, 2017
The rats are starting to jump ship. Now that whistleblowers in NASA and NOAA are in less fear, reports are coming out about the political manipulation of the data.

Feb 09, 2017
blee blaaa bloo.... Your post certainly doesn't have anything to do with what I wrote.

.. I'll stick with the facts, ..., and there will soon be much less wasted public funding researching the monster in the closet.

It would seem that you maybe qualify for a job a McD's, better hurry cause the robots are coming.

Misunderstanding the facts again monkey poo ? It has everything to do with you, The link i added is what shows YOU not even understanding primary school science, YOU didn't even know that pH is a log scale :D ! here it is, right here on the comment section of that page:
https://phys.org/...ade.html

Now monkey you may stick with your tree climbing skill facts, we've seen you swing by plenty of times catching those bananas, and we're going to see a lot more (better keep practising now ;)
And yes, MR166 is right, and there is nothing YOU can do to change the truth, i'll be nice, you can shine my shoes ;)

Feb 09, 2017
Some of you are stuck with a sock fetish, you seem to have a monkey fetish, or is it a banana fetish?

Not sure what it has to do with the AGW cult, but then again nothing you say has relevance to the truth and so in that sense at least you are consistent with your faith.


Feb 09, 2017
Look at this clown (a newish antigoracle sock)you gotta love it, first we caught him out not passing primary school science, then we post a link to the evidence showing his own words, then finally he denies that it's the truth after the evidence were posted for everyone to see lol.. aaaah this is so much fun :D

Swinging around in a close loop you yourself would tend to think that you're not the one with the problem.

Completely void of the facts real Scientists have put forth over decades, as long as you keep swinging those trees and not find a way out, you will be kept fed with bananas, today you only get one, it could be 5 out of five next time (but we're not betting the house on it ;)

Feb 09, 2017
This comment has been removed by a moderator.

Feb 09, 2017
This comment has been removed by a moderator.

Feb 15, 2017
Hi Forum.

I recall, many years back, pointing out (to a guy named "Trippy" on AGW 'side') that all models, from ANY 'side' were incomplete/naive/simplistic (as to data, variables, factors), and therefore ALL models from EITHER 'sides' were misleading/open to serious errors in 'detailed' projections. He took it as a personal insult and bit my head off, and missed the point!

NOW we can ALL (on both 'sides') see the current reality unfolding before our eyes NOW; and we don't need to continue arguing models (old and newer), because the TREND is NOW clear irrespective of 'official' old/complex/normalized etc data/temp records in long past.

Recently I again pointed out (to antigoracle etc) that they too, should just stop 'fiddling while Rome burns' (ie stop trivial to-and-fro about old/new models/data etc) and just look around at the TRENDING REALITY NOW I pointed to.... http://www.abc.ne.../8268692


Feb 15, 2017
Hi Anonym. :)

I ask, as a friend in science, please ensure you do not fall into same naive/simplistic pitfalls etc you accuse the 'other side' of.

Eg (1), you assume naively:
...retreating glacier in the Alps revealed the body of a man who had died about 7,000 years ago. It had to be at least as warm then as now, n'est-ce pas?
Think about it. His body must have been on top/near surface layers, or it would have been pulverized etc as glaciers move/grind along etc. And anybody can TRAVERSE a glacier walking on its surface, even in bitterly cold temps. Yes?

Eg (2), you assume naively:
The Romans planted vineyards around York, England, back when they ran the place. It had to be at least as warm then as now, n'est-ce pas?
Think about it. The OCEAN currents/temps determine much of the previailing LOCAL/REGIONAL conditions (eg, the warm currents keep present Britain temperate, thus ameliorating its otherwise within-arctic-circle conditions). Etc.

Rethink it all. :)

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