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Jesper Björklund

Researcher

Department of Earth Sciences
Mail
jesper.bjorklund@gu.se
Visiting address
Medicinaregatan 7 B
41390 Göteborg
Postal address
Box 460
40530 Göteborg

About Jesper Björklund

Research interests

I am a researcher in Physical Geography at the Department of Earth Sciences, University of Gothenburg, and a member of Gothenburg University Laboratory of Dendrochronology (GULD). My research interests revolve around trying to extract as pure and strong climatic information from tree-rings as possible. I use this information with the overarching goal of providing accurate climate reconstructions that will constitute a sound observational basis for past millennia climate model simulations.

Each wood cell in the tree-rings has been affected by the weather under which it was formed, and by analyzing thousands of cells in each tree ring, exceptionally pure information about past climate can be obtained. Using this approach, I, together with colleagues, reconstructed summer temperatures in Northern Fennoscandia over the past 1200 years using c. 50 million cells showing that the current warming is unprecedented during this time. This research, published in Nature, was featured in various news outlets from Forskning och Framsteg to Washington Post

https://fof.se/artikel/2023/8/medeltidens-klimat-var-inte-varmare-an-nu/

https://www.washingtonpost.com/business/2023/08/04/what-the-medieval-warm-period-can-tell-us-about-climate-change-today/bb919220-32c9-11ee-85dd-5c3c97d6acda_story.html

I believe this type research is of major importance and especially timely because 1) Trees are biological archives and when they die they start to decomposed. The valuable tree-ring archive is thus relentlessly dissapearing as time goes by. 2) The technique of anlysing cells in tree-rings have in the past been very time-consuming. With new developments using AI facilitated image analyses, this research has become accessible on a new scale. My dream is to build up hemispheric networks using this exceptionally accurate data to be able to understand if climate impact from major volcanic eruptions can be detected in the Southern Hemisphere using natural climate proxy archives. Current state-of-the-art climate proxies and climate model simulations notably disagree about the role of volcanisms on climate impact in this hemisphere.

Apart from this I am heavily involved in fostering the use of the affordable tree-ring based climate proxy Blue Intensity (BI). This is valuable for, and widely used by less wealthy labs around the world. I am currently Guest editing a Special Issue in the journal Dendrochronologia on this topic, see https://www.sciencedirect.com/journal/dendrochronologia/special-issue/104DSSLMRDZ.