• Lakes are changing worldwide: Human acti

    From ScienceDaily@1337:3/111 to All on Mon Oct 18 21:30:32 2021
    Lakes are changing worldwide: Human activities to blame

    Date:
    October 18, 2021
    Source:
    Vrije Universiteit Brussel
    Summary:
    Worldwide, lake temperatures are rising and seasonal ice cover is
    shorter and thiner. This effects lake ecosystems, drinking water
    supply and fishing. International research now shows that these
    global changes in lake temperature and ice cover are not due to
    natural climate variability. They can only be explained by massive
    greenhouse gas emissions since the Industrial Revolution. To
    demonstrate this, the team has developed multiple computer
    simulations with models of lakes on a global scale, on which
    they ran a series of climate models. The researchers found clear
    similarities between the observed changes in lakes and model
    simulations of lakes in a climate influenced by greenhouse gas
    emissions. Besides measuring the historical impact of climate
    change, the team also analyzed various future climate scenarios.



    FULL STORY ========================================================================== International research led by Luke Grant, Inne Vanderkelen and Prof Wim
    Thiery of the VUB research group BCLIMATE shows that global changes in
    lake temperature and ice cover are not due to natural climate variability
    and can only be explained by massive greenhouse gas emissions since the Industrial Revolution. The influence of human-induced climate change is
    evident in rising lake temperatures and in the fact that the ice cover
    forms later and melts sooner.


    ========================================================================== "These physical properties are fundamental to lake ecosystems," says
    Grant, a researcher at VUB and lead author of the study. "As impacts
    continue to increase in the future, we risk severely damaging lake
    ecosystems, including water quality and populations of native fish
    species. This would be disastrous for the many ways in which local
    communities depend on lakes, ranging from drinking water supply to
    fishing." The team also predicted future development under different
    warming scenarios.

    In a low-emission scenario, the average warming of lakes in the future is estimated to stabilise at +1.5DEGC above pre-industrial levels and the
    duration of ice cover to be 14 days shorter. In a high-emission world,
    these changes could lead to an increase of +4.0 DEGC and 46 fewer days
    of ice.

    At the beginning of the project, the authors observed changes in lakes
    around the world: temperatures are rising and seasonal ice cover is
    shorter. However, the role of climate change in these trends had not
    yet been demonstrated.

    "In other words, we had to rule out the possibility that these changes
    were caused by the natural variability of the climate system," says
    fellow VUB researcher and study co-author Vanderkelen.

    The team therefore developed multiple computer simulations with models
    of lakes on a global scale, on which they then ran a series of climate
    models. Once the team had built up this database, they applied a
    methodology described by the Intergovernmental Panel on Climate Change
    (IPCC). After determining the historical impact of climate change on
    lakes, they also analysed various future climate scenarios.

    The results show that it is highly unlikely that the trends in lake temperatures and ice cover in recent decades can be explained solely
    by natural climate variability. Moreover, the researchers found clear similarities between the observed changes in lakes and model simulations
    of lakes in a climate influenced by greenhouse gas emissions.

    "This is very convincing evidence that climate change caused by humans has already impacted lakes," says Grant. Projections of lake temperatures and
    ice cover loss unanimously indicate increasing trends for the future. For
    every 1DEGC increase in global air temperature, lakes are estimated
    to warm by 0.9DEGC and lose 9.7 days of ice cover. In addition, the
    analysis revealed significant differences in the impact on lakes at the
    end of the century, depending on the measures taken by humans to combat
    climate change.

    "Our results underline the great importance of the Paris Agreement
    to protect the health of lakes around the world," says Wim Thiery,
    VUB climate expert and senior author of the study. "If we manage
    to drastically reduce our emissions in the coming decades,
    we can still avoid the worst consequences for lakes worldwide." ========================================================================== Story Source: Materials provided by Vrije_Universiteit_Brussel. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Grant, L., Vanderkelen, I., Gudmundsson, L. et al. Attribution
    of global
    lake systems change to anthropogenic forcing. Nature Geoscience,
    2021 DOI: 10.1038/s41561-021-00833-x ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2021/10/211018112456.htm

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