If you are looking for high resolution paleoclimate records during the Younger Dryas, I would recommend ice cores like the GISP2 or stalagmite in China. Hope that helps.

This book and the references in it might help you:  

Roberts, Neil. 2014. The Holocene: An Environmental History. 3rd Edition edition. Hoboken, NJ: Wiley-Blackwell.  

"The Holocene provides students, researchers and lay–readers with the remarkable story of how the natural world has been transformed since the end of the last Ice Age around 15,000 years ago. This period has witnessed a shift from environmental changes determined by natural forces to those dominated by human actions, including those of climate and greenhouse gases. Understanding the environmental changes – both natural and anthropogenic – that have occurred during the Holocene is of crucial importance if we are to achieve a sustainable environmental future."  

You might also find this book useful:  

Alley, Richard B. 2000. The Two-Mile Time Machine. Princeton, New Jersey, USA: Princeton University Press.  

"The Two-Mile Time Machine begins with the story behind the extensive research in Greenland in the early 1990s, when scientists were beginning to discover ancient ice as an archive of critical information about the climate. Drilling down two miles into the ice, they found atmospheric chemicals and dust that enabled them to construct a record of such phenomena as wind patterns and precipitation over the past 110,000 years. The record suggests that "switches" as well as "dials" control the earth's climate, affecting, for example, hot ocean currents that today enable roses to grow in Europe farther north than polar bears grow in Canada. Throughout most of history, these currents switched on and off repeatedly (due partly to collapsing ice sheets), throwing much of the world from hot to icy and back again in as little as a few years."        

Since the Younger Dryas is the most extensivily researched stage in the Late Pleistocene, your question is too broad to answer. I would not focus on a specifiek type of source (ie Ice cores) since other studies show a completely different picture, for instance

http://www.geol.lu.se/personal/seb/Geology.pdf.pdf

For the Younger Dryas one could say that nothing is as it seems. It would help if you could reveal the type of species.

It may be good if you concentrate on Northern and Western Europe where the Younger Dryas Event might have the largest effect on vegetation and has also been well evidenced and mapped.

Daniel,   Guoyu mentioning Northern and Western Europe reminded me of this paper which you might find interesting. It is the exception that proves the rule. Maslin, M. A, and S. J Burns. ‘Reconstruction of the Amazon Basin Effective Moisture Availability over the Past 14,000 Years.’ Science 290, no. 5500 (2000): 2285.

I'm currently running a simulation for the Younger Dryas. There is an older simulation called "TraCE" with CCSM3. Data can be downloaded from

https://www.earthsystemgrid.org/project/trace.html

I'm however not sure to which extent the simulation is correct over Eurasia. In my high resolution simulation, the summers are not really colder but winters are. TraCE shows a very strong summer cooling.

There is another paper here about the Younger Dryas which I find think is important.   Broecker, Wallace S. ‘Abrupt Climate Change Revisited’. Global and Planetary Change 54, no. 3 (2006): 211–15. http://www.sciencedirect.com/science/article/pii/S092181810600186X

@Alistair: I like the old papers very much. However, it is very important to read briefly all of them. We are far from a consistent view on the Younger Dryas. It is to some extent misleading to rely only on ice cores vs. marine sediments vs. terrestrial proxy etc. Models tend to be run in a way to match Greenland and Antartica. Might not be the full story though.

@Frederik

Younger Dryas winters may have been colder but there is ample evidence from multiple palynlogical studies etc that the summer was warmer but drier (a lot), consistent with a plethora of studies for the USA that point to a shift from C3 to C4 photosynthesis. Of course this is all highly controversional, compared to the alleged isotope temperature proxy.

Obviously modelling will suffer from inconsistent data interpretations.

Frederik,

Ouch! It seems like only yesterday when Broecker's paper was published. I must be getting very old :-(

What is the latest thinkiing on the mechanisms which drove the YD? AFAIK, that 2006 paper is the last to discuss the matter.

Daniel,

There is an issue of the PAGES magazine here which mentions the YD. It might be useful: http://www.pages-igbp.org/products/pages-magazine/5114-23-1-glacial-terminations-and-interglacials

@Andre:

Could you suggest one or some recent papers about warm but dry summers during Younger Dryas? I currently look at pollen-based temperatures but I'm not sure if it is really only temperature...

Alistair

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4035952/

Younger Dryas deglaciation of Scotland driven by warming summers

Frederik, I ref a few, but I would suggest to scholar.google on terms like younger dryas c4 vegetation warm summers etc. Also note that not everybody is happy to shout from the roofs that they discovered something that challenged mainstream, so often you have to infer things implicitely, like analysing the species temperature ranges and as said C4 photosynthesis shift like this one:

http://agrilife.org/boutton/files/2013/01/Nordtetal2002_6.pdf

Also don't take it for granted if they haste to model the anomaly away ie Bjorck et al 2002.

Furthermore:

Ager T.A. 2003, Late Quaternary vegetation and climate history of the central Bering land bridge from St. Michael Island, western Alaska Quaternary Research, Volume 60, Issue 1, July 2003, Pages 19-32

Björck, S., Bennike O., Rosén P., Andresen C., Bohncke S., Kaas E., Conley D., 2002. Anomalously mild Younger Dryas summer conditions in southern Greenland. Geology May, v. 30; no. 5; pp. 427–430.

Lücke, A. Brauer A., 2004. Biogeochemical and micro-facial fingerprints of ecosystem response to rapid Late Glacial climatic changes in varved sediments of Meerfelder Maar (Germany). Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 211, Issues 1- 2, 19 August.

Thx Andre and don't worry, I do not take anything for granted anymore. I will have a meeting with Svante Björck next month. I have severe problems with all the proxy data and how it is interpreted in the papers. What we try is to collect as much as possible proxy data to get a better spatial impression. Then I can compare it with my high resolution simulation of the Younger Dryas and late Alleröd. Maybe the role of the AMOC is also exaggerated as major player in summer. We will see.

You're welcome.

Incidentely, almst  the same problem arizes roughly in the period 17.5-14.5 ka, which is dubbed the mystery interval  (Denton et al 2006 Pages)

So the next thing that should be of interest, is why the oxygen isotope records over the YD, like the Greenland ice cores,  speleothems, lake sediments do show the big dip, suggesting the big drop in temperatures, while this not supported in other records and proxies. 

The answer to that question would really shatter a widely believed paleoclimatologic  misconception.

http://www.pages-igbp.org/download/docs/newsletter/2006-2/science_highlights/Denton_etal_2006-2(14-16).pdf

Exactly!! I just asked a colleague here that question on Monday why 18O shows such a cooling while other proxy types don't.  So whether the 18O might not just reflect the cold ocean state but not the actual temperature on land etc. Same for ice cores etc. Very good to see that others pose the same questions because I'm only a climate modeller and not a proxy expert.

The answer is that d18O is not a proxy for global surface temperatures. Willy Dansgaard was not wrong. He just was not a hydrologist and he did not oversee all the variables. (I'm neither a hydrologist but I figured it out)

Interested to write that paper together?

I work with tree rings and have just started a project on a YD site here in New York.  I have also worked on earlier late glacial sites in NY.  I agree with the lack of high resolution records for the YD and the possibility of different conditions around the globe!  So far, with 14C dates, I have the end of the mastodons at around 12,700 cal BP at the older sites, then trees indicating good growth conditions starting at ~12,600, definitely by 12,500 at the YD site.   Perhaps the ice core 18O reflects more the size and proximity of the ice sheet and the route of meltwater drainage?

My knowledge is not good enough to write about that. I just managed to put at least a question mark to d18O. That could be either due to my limited personal knowledge or due to a real problem. So you say it is a real problem?

I just see that my Younger Dryas simulation will not match cold summers suggested by d18O. However, also vegetation seems to show colder conditions but as I said before, it could be also dry, short vegetation season (growing degree days) etc.

Frederick,

Both the Broecker paper I cited and the paper Harry cited describe warm summers but cold winters.

Harry,

Thank you for the link to that paper, but I suspect it is not saying what you think. It is not saying the YD ended in Scotland because of warm summers. It is saying that the ice sheet which formed on the Scottish Highlands had melted away before the YD ended, perhaps as early as half way through the YD. That raises the question of when it formed. I suggest that it formed during either the Older Dryas or the IACP, and disappeared during the Younger Dryas due to the cold dry winds coming off the sea ice that formed in the North Atlantic during the winters.

So it does not explain the abrupt end to the YD, but it does confirm my suspicion that what caused the YD to start is still up for grabs. The start the paper reads: "Determining the causes of abrupt climate change remains an outstanding question of palaeoclimatology, ..."

@Alastair

yes thx I saw some warm summer papers now but I cannot just take them because they agree with my model and dump the rest into the septic tank ;-)

The question remains what is reflected by different proxies (in terms of variable space) when not taking so far results for granted. Are the empirical or physical transfer functions multi-variate, are they stationary?

Frederick

The Lücke and Brauer 2003 ref I gave for the Meerfelder Maar in Germany. If you look into detail of the species in the pollen diagram during the YD,

https://dl.dropboxusercontent.com/u/22026080/meerfelder.gif

Helianthemum is mostly a mediterian genus, Germany being close to it's northermost distribution currently.  Also Sanguisorba officinalis is  listed with limited winterhardiness. Also absent are typical (sub)artic genera like Dryas. What we see here are meadow flowers just like they are there today. There is nothing in there that suggests that de YD had a different climate from today during the YD.

Andre,

Perhaps the Meerfelder Maar is the refugia Daniel is looking for :-)

I have yet another, much better refugia, northernmost Siberia.

http://epic.awi.de/9052/1/Hub2004a.pdf

Check in particular fig 6 on page 1339

Note that the YD under B is part of the last phase of the Late Weichselian (Sartanian) LW II with Dry and warm summer - Warmest tundra steppe.

Not sure about that one. I reckon that the LWII is the Bolling-Allerod inter stadial and the YD is missing in an unconformity.

At NOAA Paleoclimate data website you can find a lot relevant data:

https://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets

Regards, Yi

Alistair

I reread the publication on the deglaciation of Scotland

The authors show that it is summer heat rather than dry conditions that give rise to the melting of the glaciers.

""some reconstructions suggest enhanced YDS precipitation in Scotland (24, 25), which is inconsistent with the explanation that precipitation starvation drove deglaciation (26).We prefer an alternative scenario in which glacier recession was driven by summertime warming and snowline rise"

Or else please show me where they write otherwise

Harry,

You are quite right. I had missed that. They prefer an alternative scenario. But the point I am making is that it was not the warm summers which caused the YD to end abruptly. The mini ice sheet in Scotland had disappeared 500 years before the end of the YD, and during those years presumably the warm summers continued.

Frederick,

The following papers also argue for warm summers during the YD

Björck S, et al. Anomalously mild Younger Dryas summer conditions in southern Greenland. Geology. 2002;30(5):427–430.

Ballantyne CK. The Loch Lomond Readvance on the Isle of Mull, Scotland: Glacier reconstruction and palaeoclimatic implications. Jour. Quat. Sci. 2002;17(8):759–771

Benn DI, Lukas S. Younger Dryas glacial landsystems in western Scotland: Possible modern analogues and palaeoclimatic implications. Quat Sci Rev. 2006;25(17-18):2390–2408.

Alistair

The issue herei is not of the ending but the questioner asked for climate parameters DURING the YD

and in contrast to earlier ideas summers seem to have been qnot colder than "normal"

Contact: https://www.uea.ac.uk/environmental-sciences/people/profile/p-jones

Pradeep

I googled-scholar for Jones and Younger Dryas but got zilch apart from ClimateGate

Harry

Maybe you should also have a look at climategate.nl in Dutch, check my latest articles about the refutal of the isotope paleothermometer 

Hi,

I see that the discussion here went very much off topic. But I would like to repeat the original question since it is also relevant to my studies. What I am looking for (and presumably Daniel as well) is a map that contains 19 bioclimatic variables or at least some data about temperature and precipitation that might allow to reconstruct those 19 variables which are widely used to model potential paleo-distributions of plants. It is something like here: http://www.worldclim.org/paleo-climate

So I was also searching for such data but without success. Since there are people working with past climate reconstructions maybe there is an idea or source that might help?

I provided a link to modeling data on the first page of this discussion. You can download the data and create own maps for key variables. If you have any problems with creating maps from the data, just write me a PM and I might help you out. There is generally not so much data available for the Younger Dryas as it was not a period in the PMIP projects.

Kamil,

Are you looking for the results from computer simulations, or from records of fossils, ice and sediment cores, pollen counts etc? I had assumed that it was the latter, but if so, I suspect you will have to construct you own since no one has yet produced a global record for that period.