EGU2020-4638
https://doi.org/10.5194/egusphere-egu2020-4638
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Causes of future Mediterranean precipitation decline depend on the season

Roman Brogli, Silje Lund Sørland, Nico Kröner, and Christoph Schär
Roman Brogli et al.
  • ETH Zurich, Institute for Atmospheric and Climate Science, Zürich, Switzerland (roman.brogli@env.ethz.ch)

The Mediterranean is among the global 'hot-spots' of climate change, where severe consequences of climate change are expected. Changes in the atmospheric water cycle are among the leading causes of the vulnerability of the Mediterranean to greenhouse gas-driven warming. Specifically, precipitation is projected to decrease year-round, which is expected to have major impacts on hydrology, biodiversity, agriculture, hydropower, and further economic sectors that rely on sufficient water supply.

We investigate possible causes of the Mediterranean drying in regional climate simulations. To isolate the influence of multiple large-scale drivers on the drying, we sequentially add the respective drivers from global models to regional climate model simulations. We show that the causes of the Mediterranean drying depend on the season. We will present in detail how the summer drying is driven by the land-ocean warming contrast, lapse-rate and other thermodynamic changes, while it only weakly depends on circulation changes. In contrast, changes in the circulation are the primary driver for the projected winter precipitation decline. Since land-ocean contrast, thermodynamic and lapse-rate changes are more robust in climate simulations than circulation changes, the uncertainty associated with the projected drying should be considered smaller in summer than in winter.

Reference: Brogli, R., S. L. Sørland, N. Kröner, and C. Schär, 2019: Causes of future Mediterranean precipitation decline depend on the season. Environmental Research Letters, 14, 114017, doi:10.1088/1748-9326/ab4438.

How to cite: Brogli, R., Sørland, S. L., Kröner, N., and Schär, C.: Causes of future Mediterranean precipitation decline depend on the season, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4638, https://doi.org/10.5194/egusphere-egu2020-4638, 2020

How to cite: Brogli, R., Sørland, S. L., Kröner, N., and Schär, C.: Causes of future Mediterranean precipitation decline depend on the season, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4638, https://doi.org/10.5194/egusphere-egu2020-4638, 2020

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Presentation version 2 – uploaded on 30 Apr 2020
Hyperlinks to journal webpages added
  • CC1: Comment on EGU2020-4638, Francisco Pastor, 08 May 2020

    Dear Dr. Brogli, congratulations on your excellent work and absolutely nice presentation.

    If I understand you have studied yearly precipitation but what about extreme precipitation events in the Mediterranean. They are an important contribution to the annual precipitation volume and maybe it would be interesting to know if the decline in precipitation will affect them. Do you plan to extend your study to different types of precipitation events? Is it possible? Can you assign the precip decline to such rain event types?

    Thanks in advance and best regards

    • AC1: Reply to CC1, Roman Brogli, 08 May 2020

      Hello, thanks alot for your question!

      In the paper that belongs to our display we have also computed daily precipitation change statistics and quantified the influence of all large scale drivers on those. What you can see is that the intensity of precipitation events is projected to increase which is driven by thermodynamics (clausius-clayperon relation). The frequency of precipitation in the Mediterranean is decreasing which is caused by thermodynamics & dynamics in summer and only by dynamics in winter. (, Figure 3 + 4)

      These daily statistics are however not only the most extreme events and we have chosen not to look at these in detail in our simulations as they are quite coarse resolution (dx ~ 50km) and nowadays there are better tools for extreme precipitation research.

      A nice publication on more extreme events that you may know is this one: .

      Moreover my colleague Nikolina Ban has conducted convection resolving simulations over Europe and looked at the extreme precipitation response in the Mediterranen. That paper should come out hopefully soon in Nature Climate Change. Maybe have an eye out for that one.

      Best Roman

      • AC2: Reply to AC1, Roman Brogli, 08 May 2020

        Sorry the links are not displayed correctly:

        One link was www.nature.com/articles/nclimate3287 

        The link to our study is iopscience.iop.org/article/10.1088/1748-9326/ab4438

        • CC2: Reply to AC2, Francisco Pastor, 08 May 2020

          Thank you very much for your answer and for the references.

          Best regards,
          Paco

Presentation version 1 – uploaded on 16 Apr 2020 , no comments