European summer droughts since 2015 ‚most severe in centuries‘, but multi-year droughts also happened in the past

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From Tallbloke’s Talkshop

February 17, 2023 by oldbrew 

Freighter passing a sandbank on the Rhine river [image credit: worldcargonews.com]

Mixed messages from climate research here. In between evidence-free waffle about ‘potential’ human influence, they report that severe drought spells are nothing new in Europe, implying climate cycles of some sort. This means attribution of such drought to human causes is debatable, as the article admits.
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The 2015–2018 summer droughts have been exceptional in large parts of Western and Central Europe over the last 400 years, in terms of the magnitude of drought conditions.

This indicates an influence of man-made global warming, claims Phys.org.

However, multi-year droughts have occurred frequently in the 17th and 18th century, although not as severe.

This is the result of a new study in the journal Communications Earth & Environment.

It was conducted by a research team led by Mandy Freund from the University of Melbourne and Gerhard Helle from the GFZ German Research Centre for Geosciences. They reconstructed European summer hydroclimate by analyzing the isotopic ratios of carbon (13C/12C) and oxygen (18O/16O) in tree-rings from a European network of forest sites.

It is the first spatial field reconstruction based on highly climate-sensitive tree-ring isotopes. This provides researchers with a unique tool for investigating climatic developments over the past centuries, both in a global overview and in a regionally differentiated manner.

European hydroclimate development

Recently, Europe has seen an increase in floods and droughts. These extreme events are part of the complex dynamics of European hydroclimate.

Obtaining a precise spatially-resolved picture of the dynamics in frequency and intensity of extremes at regional to local scale is a challenge, especially in the context of longer-term climatic variability.

Little is known about the long-term, spatiotemporal hydroclimatic variability across Europe due to the rather sparse availability of spatially explicit data series that properly reflect regional differences.

The European summer drought from 2015 to 2018 has particularly caused discussions about whether it falls within the normal range of climate fluctuations or is a result of anthropogenic warming.

New approach to reconstructing the hydro-climate of the last 400 years

To resolve this issue a spatially resolved reconstruction of European hydroclimate over the last 400 years was developed and published in the journal Communications Earth & Environment.

It is based on the analysis of stable carbon and oxygen isotopes, i.e. variants of these elements with different masses, in old tree stands from 26 forest sites across Europe.

Full article here.
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Study: European tree-ring isotopes indicate unusual recent hydroclimate (2023)
Quote: ‘We find three distinct phases of European hydroclimate variability as possible fingerprints of solar activity (coinciding with the Maunder Minimum and the end of the Little Ice Age) and pronounced decadal variability superimposed by a long-term drying trend from the mid-20th century.’