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

Posted: February 17, 2023 by oldbrew in climate, Cycles, data, research, trees, Uncertainty
Tags: ,

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

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

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.’

  1. Jaime Jessop says:

    That’s a shame, they could only go back as far as 1600 and they found that the 2015-2019 European drought was unprecedented. Just 60 years earlier, in 1540, Europe probably experienced its worse drought in a thousand years, which may have been part of a multi-year pattern, and which was almost certainly more severe than the summer drought and heatwaves of 2003 or 2015-19. The 1540 drought lasted 11 months.

  2. oldbrew says:

    Good point JJ.

    Orth et al. (2016)[4] concluded that in summer 1540 the mean temperature was above the 1966–2015 mean and with a probability of 20% exceeded that of the 2003 summer.

    The Swiss historian Christian Pfister described the events of 1540 in a newspaper interview:[5]

    For eleven months, there was practically no rain, temperatures were five to seven degrees [Celsius] [9–13 °F] above the normal values for the 20th century, in many places summer temperatures must have exceeded 40 °C (104 °F).

    Read more —

  3. catweazle666 says:

    In “Climate Science” it seems “unprecedented” starts the day after the last time there was a hotter/colder/wetter/dryer event/period, Jaime.
    So it can be anything from the day before yesterday to ten thousand years ago.

  4. stpaulchuck says:

    Jaime Jessop says:
    February 17, 2023 at 4:21 pm

    Jaime, they always cherry pick the years. They do it regularly with AGW: “The most/worst since the beginning of the Industrial Age,” which coincidentally was about the end of the Little Ice Age. Hmmm, ice age = cold, not the ice age = warm, and moving from ice age to not ice age means warming. Gee, I wonder… (not so much really).

  5. oldbrew says:

    Channel 5 showed part 2 of The Great Stink last night…

    In June 1858 the temperatures in the shade in London averaged 34–36 °C (93–97 °F)—rising to 48 °C (118 °F) in the sun.[7][31] Combined with an extended spell of dry weather, the level of the Thames dropped and raw effluent from the sewers remained on the banks of the river.[7] Queen Victoria and Prince Albert attempted to take a pleasure cruise on the Thames, but returned to shore within a few minutes because the smell was so terrible.[32] The press soon began calling the event “The Great Stink”…
    . . .
    The leading article in The Times observed that “Parliament was all but compelled to legislate upon the great London nuisance by the force of sheer stench”.
    [bold added]

  6. Jaime Jessop says:

    The air is cleaner than ever in London thanks to Khan’s ULEZ and him banning wood burning stoves to prevent people keeping warm in winter without using mega expensive ‘Green’ electricity. But the stench of corruption is all around, most especially in Fleet Street, Threadneedle Street, Downing Street, City Hall and Scotland Yard.

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