EU funding for the collection of a new tree ring network covering the Northern Hemisphere and the development of tree ring growth and density models
Johannes Gutenberg Universitaet Mainz
Tree rings tell us a lot about what the climate was like in the past and are therefore used by researchers for climate reconstructions – something that is particularly relevant in a time of climate change. However, since the 1960s, the rings of trees have no longer provided an accurate reflection of temperature development. This problem, known as divergence, is the starting point for a new research project, for which paleoclimatologist Professor Jan Esper of Johannes Gutenberg University Mainz (JGU) will be receiving more than EUR 2.5 million in EU funding. Over the project’s five-year duration, Esper and his team will track the development of trees at 100 sites in the Northern Hemisphere to develop a new model for the reconstruction of tree growth that will generate reliable data for climate research. The European Research Council (ERC) has awarded Professor Jan Esper and his MONOSTAR project an ERC Advanced Grant, the EU’s most richly endowed funding award that is earmarked for outstanding researchers.
Tree rings present a prime archive in which hundreds of years’ worth of climatic developments have been recorded in great detail, from regional to global scales. However, climate reconstructions depend on reliable correlations between tree growth and climate. “It worked very well up until the second half of the last century,” explained Esper. “But since the 1960s, the tree ring width and densities have not been able to keep pace with global warming.” It was during the 1990s that the divergence problem was recognized as a phenomenon with far-reaching consequences. Not only does it undermine the reliability of temperature reconstructions based on tree rings, it also has implications for our understanding of how sensitive the Earth’s climate is to man-made greenhouse gases. “The problem impacts all climate reconstructions based on year-to-year changes over the past 1,000 to 2,000 years,” Esper pointed out.
Sampling and monitoring tree sites in the Northern Hemisphere
The scientist therefore proposed to start by collecting new data, among other tasks. To this end, Esper and his team along with cooperation partners from many different countries will launch a uniquely international project to record the growth of various species of conifers in cold locations and in boreal coniferous forests of the Northern Hemisphere. The width and density of tree rings will be measured at 100 locations, from the Rocky Mountains through the Alps and as far as the Himalayas. Additional extensive monitoring procedures will be carried out at ten of these locations in order to collect detailed findings on influencing factors so that a new tree ring density model can be created. The core samples from each of the locations will be analyzed at two laboratories in Germany, one lab in Russia, and another one in Switzerland.
Studying the influence on ecology, archeology and history beyond climate research
Paleoclimatologists suspect that temperature is not necessarily the only decisive factor in the divergence problem. “There are many other influencing factors that can influence plant growth in extreme locations, such as levels of ozone or changes in radiation,” added Esper. The results of MONOSTAR, an acronym for Modeling Non-Stationary Tree Growth Responses to Global Warming, could have far-reaching consequences: If historical warm periods and climate changes can be reconstructed more accurately, this will not only help climate researchers, but will also spark new research ideas in ecology, archeology, and historical studies.
Distinction for scientific excellence
Jan Esper studied and later earned a doctorate in geography at the University of Bonn. After a postdoc position at Columbia University in New York City, he continued his work on dendrochronology at the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), and qualified as a professor at the University of Bern. Since 2010, Esper has been a professor at the Department of Geography at Johannes Gutenberg University Mainz. He became a member of the Academy of Sciences and Literature in 2018. His research focuses on the paleoclimate, urban climate, and dendrochronology.
ERC Advanced Grants are awarded to outstanding researchers to enable them to undertake projects considered to be highly speculative due to their innovative approach, but which, because of this, can open up access to new approaches in the corresponding research field. Only researchers who have already made significant breakthroughs and have been successfully working for at least ten years at the highest levels of international research are eligible for the grant. The only criteria considered in awarding ERC funding are the academic excellence of the researcher in question and the nature of their research project. An ERC grant thus also represents acknowledgement of the individual achievements of the recipient.
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Related links:
https://www.blogs.uni-mainz.de/fb09climatology/ – Climatology Group at the JGU Institute of Geography
https://erc.europa.eu/news/erc-2019-advanced-grants-results – ERC press release “€450 million for Europe’s long-term frontier research”
https://erc.europa.eu/news-events/magazine/erc-2019-advanced-grants-examples – ERC 2019 advanced grants examples
Read more:
https://www.uni-mainz.de/presse/16168_ENG_HTML.php – press release “Natural climate archives play an important role in climate reconstructions of past millennia” (4 Feb. 2013)
https://www.uni-mainz.de/presse/16094_ENG_HTML.php – press release “International team of researchers publishes first reconstruction of Eastern European springtime temperatures since the Middle Ages” (15 Jan. 2013)
https://www.magazin.uni-mainz.de/970_ENG_HTML.php – JGU MAGAZINE “Finnish trees tell the story of 2,000 years of climate history” (22 Aug. 2012)
https://www.uni-mainz.de/presse/15491_ENG_HTML.php – press release “Climate in northern Europe reconstructed for the past 2,000 years: Cooling trend calculated precisely for the first time” (9 July 2012)
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The more I think about this, the more I see exceptions to the tree-rings display temperature hypothesis.
Dendro-chronology works well because there are so many variables at play in tree ring formation.
Well, you can’t make the tree ring proxy data any worse… So they have that in their favor!
“Tree rings tell us a lot about what the climate was like in the past”
No, they’ll only tell you whether general conditions were favorable or not for tree growth. You won’t know whether those favorable conditions were due to temperature, moisture, nutrient availability, etc.
“But since the 1960s, the tree ring width and densities have not been able to keep pace with global warming.” It was during the 1990s that the divergence problem was recognized as a phenomenon with far-reaching consequences”
Don’t temperature reconstructions have large uncertainties anyway and therefore use multiple proxies?
https://tambonthongchai.com/2019/04/02/mwp/
Did they ever apart from spurious correlations in a select few trees?
Why don’t they do this?
Photosynthesis. NOT Thermosynthesis, or even Thermo-photosynthesis.
Grant application rejected, if it were down to me.
Check out table 1S in this paper by Wahl and Amman “Verifying” Mann, Bradley, Hughes ‘ 1998 “Hockey Stick” paper,
https://ral.ucar.edu/projects/rc4a/millennium/refs/Wahl_ClimChange2007.pdf
For the “verification period”, r² was less than 0.02 for all years prior to 1759. The models don’t just suck post 1960, they suck for 1400 to 1749 also,
There are so many species and sub-species of conifers across the globe that it is unbelievable. Their growth rates vary widely just based on species differentiation let alone local environmental conditions.
1. Taking samples from some place in Colorado and some place in the Himalayas and trying to compare them is a waste of time because of simple genetic drift even in the same species.
2. If they use the same seeds in controlled plots in widely varying geographical locations then their results will not only take years to collect, the results will have absolutely no correspondence with naturally growing conifers. You may as well just depend on local thermometers.
There are so many confounding variables at play in nature that, as someone else said, any statistical analysis depending on one variable will be impossible, it would be voodoo science. Not only are rainfall, temperature, and cloud cover confounding variables but so are local animal populations, root competition with other plants and trees, insect infestations, parasitic vine impacts, and shade from other trees which changes over time. These are just off the top of my head, there are probably lots of others. There is simply no way to control for these variables in widely separated geographical locations. It’s probably impossible to do even in a single, local location because this kind of data is simply not available.
Has anyone tried looking at violins ? ( instead of hockey sticks)
We have violins going back to the mid 16th Century.
IN the 17th century, we have all the violins from Cremona, such as Stradivari and Guarneri.
Tree ring analysis can be useful but there are too many variables involved. I work in woodland management and an important fact that is ignored is that growth rates of trees vary depending on:
Species
Light levels (within the same woodland a tree with more light can be twice as wide as a tree of the same species and age that doesn’t have that light)
Age of tree( trees grow slowly, then quickly then slowly as a factor of age, usually some trees such as yew have more complex growth rates)
Soil type/quality ( again huge variations in growth)
Rainfall ( some species will shed leaves as early as June in drought, this would show a small growth ring which would imply a cold year when in fact it may well be a record breaking hot year)
Tree form and management ( not even going to bother filling in the variables here)
And many others that I can’t even be bothered to think of!
All in all most species are poor indicators of temperature BUT they are very useful in terms of noting their historic ranges. For instance small leaved lime once covered vast areas of the UK ( pre bronze age) up to an altitude of 800m, now it is very restricted and only recently has been found to be regenerating from seed. Evidence to me of a warm climate followed by a colder climate followed by a recently warming climate ( although not as warm as pre bronze age)
“Did lead author Jan Esper mislead journalists by overstating implications of his recent tree-ring study in a way that favored a contrarian anti-IPCC spin on this study.” Mann on facebook
Esper is no” “Hockey Stick” apologist. This paper points out flaws in Hughes “heterogeneous medieval warm period” papers.
https://doc.rero.ch/record/315377/files/10584_2008_Article_9492.pdf
In this paper, Esper et al, indicate that temperatures fluctuated significantly over the last 2000 years, and that some other proxies may be underestimating warming during Roman times and during the Medieval Warm Period:
“…ere,
we present new evidence based on maximum latewood
density data from northern Scandinavia, indicating that
this cooling trend was stronger (0:31 C per 1,000 years,
0:03 C) than previously reported, and demonstrate that
this signature is missing in published tree-ring proxy records.
The long-term trend now revealed in maximum latewood
density data is in line with coupled general circulation
models7,8 indicating albedo-driven feedback mechanisms and
substantial summer cooling over the past two millennia
in northern boreal and Arctic latitudes. These findings,
together with the missing orbital signature in published
dendrochronological records, suggest that large-scale nearsurface
air-temperature reconstructions9–13 relying on treering
data may underestimate pre-instrumental temperatures
includingwarmth during Medieval and Roman times.
Allan, you should go to Climate Audit and search on Esper: https://climateaudit.org/?s=esper
I this paper lead author Jan recognizes the inherent problem of proxy reconstructions sampling on the dependent variable à la Mann et al.:
‘…On the other hand, consideration of all records presented here would likely pro-mote a less variable climate history, as the combination of diverging records tends to reduce variance in the mean time series … If such a mean is then combined with instrumental data covering the past 100–150 years, this approach might facilitate hockey stick-shaped reconstructions …’.
https://www.blogs.uni-mainz.de/fb09climatology/files/2012/03/Esper_2012_GPC1.pdf