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Volume 10 Issue 2, 2 February 2020

Hotter summers dry Alpine rivers

Mountain forest drought. Increases in water consumption from vegetation (green water) at the expense of streamflow in rivers (blue water). Fatichi and colleagues quantify this for a 2003 European Alps heatwave and drought, highlighting underappreciated vulnerability of blue water resources to future warmer summers. Such a finding has implications for vegetation functioning and water resource management of mountainous regions.

See Fatichi et al. and Maxwell

Image: Paolo Burlando, ETH Zurich. Cover Design: Valentina Monaco.


  • In the upper atmosphere, ozone is essential to protect the planet through absorption of ultraviolet radiation; but at ground level, ozone is a pollutant, and increasing anthropogenic emissions are resulting in higher levels. Reducing emissions would mitigate the harmful effects of ozone as well as potentially increasing a natural carbon sink.



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  • Framing solutions to climate change as natural strongly influences their acceptability, but what constitutes a ‘natural’ climate solution is selected, not self-evident. We suggest that the current, narrow formulation of natural climate solutions risks constraining what are thought of as desirable policy options.

    • Rob Bellamy
    • Shannon Osaka
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Research Highlights

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News & Views

  • For years, halogens have been known as destroyers of ‘good’ ozone, which acts as an upper-atmosphere shield from harmful ultraviolet radiation. Research now shows that natural halogen compounds emitted from the ocean help to control ‘bad’ ozone pollution at ground level and may continue to do so at a similar rate in future climate.

    • Andrea Stenke
    News & Views
  • The impacts of climate change on the ecohydrology of forested mountain regions are uncertain. New high-resolution modelling suggests that during a hot, dry summer in the Alps, stressed vegetation capitalizes on downslope water subsidies, amplifying runoff deficits and further depleting water resources.

    • Reed M. Maxwell
    News & Views
  • Ground-level ozone is an air pollutant that is harmful to human health, as well as to plants, trees and crops. New analyses based on Earth system modelling show that reducing ozone from the energy, industrial and transportation sectors could mitigate climate change by enhancing the ability of vegetation to remove carbon dioxide from the atmosphere through photosynthesis.

    • Benjamin S. Felzer
    News & Views
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  • As tundra ecosystems respond to rapid Arctic warming, satellite records suggest a widespread greening. This Perspective highlights the challenges of interpreting complex Arctic greening trends and provides direction for future research by combining ecological and remote sensing approaches.

    • Isla H. Myers-Smith
    • Jeffrey T. Kerby
    • Sonja Wipf
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  • The rapid growth of climate change research presents challenges for IPCC assessments and their stated aim of being comprehensive, objective and transparent. Here the authors use topic modelling to map the climate change literature, and assess how well it is represented in IPCC reports.

    • Max W. Callaghan
    • Jan C. Minx
    • Piers M. Forster
  • The relative roles of local and remote processes in determining equatorial warming are still debated. Model simulations show that coupled feedbacks strongly damp the equatorial surface temperature response to local equatorial forcing, while amplifying the response to remote off-equatorial forcing.

    • Malte F. Stuecker
    • Axel Timmermann
    • Michiya Hayashi
  • Arctic warming is attributed to GHGs and feedbacks, but the specific contribution of ozone-depleting substances (ODS)—also potent GHGs—has never been quantified. Here, model simulations suggest ODS contributed 0.8°C of Arctic warming and led to considerable sea-ice loss during the period 1955–2005. [This summary has been amended to reflect the addendum published 28 January 2020]

    • L. M. Polvani
    • M. Previdi
    • K. L. Smith
  • Ozone forms in the atmosphere when other anthropogenically emitted gases react with sunlight and negatively impacts terrestrial gross primary productivity (GPP). Reducing emissions of ozone precursors by 50%, particularly in the road transportation and energy sectors, could increase GPP by 750 TgC yr–1.

    • Nadine Unger
    • Yiqi Zheng
    • Kandice L. Harper
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  • An Earth system model estimates that natural halogens, of marine biotic and abiotic origin, remove about 13% of present-day global tropospheric O3. Projections suggest this ratio is stable through 2100, with high spatial heterogeneity, despite increasing natural halogens.

    • Fernando Iglesias-Suarez
    • Alba Badia
    • Alfonso Saiz-Lopez
  • Mountain forest drought can paradoxically increase evapotranspiration (green water), helping vegetation at the expense of runoff (blue water). This is quantified for the 2003 event in the European Alps, highlighting underappreciated vulnerability of blue-water resources to future warmer summers.

    • Theodoros Mastrotheodoros
    • Christoforos Pappas
    • Simone Fatichi
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Amendments & Corrections

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