The Mediterranean basin is considered a “hot spot” of climate change. It displays an ongoing tendency towards drier conditions and this trend is expected to continue and possibly worsen in the coming decades. At the same time, individual events of extreme rainfall continue to cause human losses and severe economic damage.

This research task will be devoted to:

• The analysis of current data on the hydrological cycle in the Mediterranean basin. This includes participation in ongoing programmes such as Hymex (www.hymex.org).

• The use and development of regional climate models specifically tuned for the Mediterranean area.

• Obtaining reliable information on water availability and distribution in the next decades.

• Developing appropriate adaptation measures.

The methods used are coupled systems that have recently been developed for the Mediterranean region: the atmospheric model is forced at the surface by a high resolution interactive ocean model whose sea surface temperature (SST) in turn responds to small scale circulation patterns produced by the regional atmospheric model. A key improvement of this modelling tool is its ability to produce more reliable local SST and wind speed estimates which result in a more realistic description of water, heat and momentum fluxes and feedbacks between the atmosphere and the interactive ocean model. Such a description might be critical when performing future climate projections of the hydrological cycle, especially when strong air-sea interactions are expected.

Several modelling groups have taken part in the MedCORDEX (www.medcordex.eu) international effort in order to better simulate the Mediterranean hydrological cycle, to improve the modelling tools and to produce new climate scenarios.

Attention will also be paid to the reconstruction of the Mediterranean hydrological cycle in the last centuries through the analysis of paleo-data and modelling efforts. Hydrological model schemes must be improved to meet the specific requirements of semi-arid climates, accounting for the related seasonal soil water dynamics and the complex surface-subsurface interactions in such regions.

A lack of water for drinking, agriculture, industry and energy production are expected to impose risks for civil security. Therefore, it is important to assess and predict possible changes in water availability, distribution, and quality. Research needs to be impact-oriented in order to respond to crucial societal challenges resulting from changes in different components the hydrological cycle and to support adaptation and risk mitigation strategies. The appropriate context for adopting this approach is one of collaboration between scientists including hydrologists, social scientists and economists.

This Collaborative Programme places a focus on specific climate hot-spots, the Mediterranean region and mountain areas that are and are expected to be particularly vulnerable to climate variability and changes and addresses the ecological and socioeconomic challenges that are related thereto.

the Mediterranean region

The Mediterranean basin is considered a “hot spot” of climate change. It displays an ongoing tendency towards drier conditions and this trend is expected to continue and possibly worsen in the coming decades. At the same time, individual events of extreme rainfall continue to cause human losses and severe economic damage. Read more

mountain areas

Often called the “water towers” of our planet, owing to their role in providing water to the surrounding lowland areas, mountain regions are heavily impacted by climate change. Among the changes in the hydrological cycle components are glacier retreat, decrease of snowpack duration and thickness, changes in precipitation regimes, changes in aquifers, slope stability. Read more

Climate and the hydrological cycle are strongly coupled with land surface and ecosystem processes, both in the sense that modifications of the water cycle significantly affect land surface properties and ecosystem functioning, and because vegetation and land surface changes can lead to important effects on the whole hydrological cycle and on climate. This is represented in the concept of temporal and spatial cross-scale interactions.

A crucial problem is the scale mismatch between climatic variability, usually resolved at rather large spatial scales, and the much smaller scales of land surface processes.

This research task intends to address the following open questions:

• Upscaling of small-scale ecosystem and land surface changes and how to incorporate them into climate models and downscaling of climate information to properly drive land surface and ecosystem responses (Figure 2, see below).

• Assessing the impact of small-scale heterogeneities on climate variability. Here, one can ask up to which scale variations in the small-scale surface processes (e.g. evapotranspiration) affect climate dynamics, or what effect land surface heterogeneities can have on the statistics of extreme events.

• Whether changes in vegetation properties (such as vegetation patterning) and ecosystem transitions can trigger regional or global changes in climate dynamics.

The methods used to address these issues include conceptual approaches, intermediate complexity models, fully coupled, scale-crossing climate and land surface models, global and regional climate models, statistical and stochastic downscaling methods, besides the analysis of available data and the development and use of metrics to compare models and observations.

Figure 2. Linking of regional- to continental-scale land-atmosphere feedbacks with local vegetation-environment feedbacks by using a model hierarchy. (a) Current climate models account for large-scale land-atmosphere feedbacks, but do not account for local ecosystem feedbacks. (b) Linking large-scale land-atmosphere feedbacks with local vegetation-environment feedbacks by downscaling the climate model to the local feedback model. Up-scaling is based on model outcomes of the local feedback model, through parameterization of the large-scale vegetation model, leading to improved fluxes to the atmosphere model. From Rietkerk et al., Local ecosystem feedbacks and critical transitions in the climate,  Ecological Complexity, 8, 223–228 (2011).

Precipitation changes at the global level display a complex pattern, without a clear-cut average trend in the last century but with an apparent tendency to the intensification of the hydrological cycle in many areas of the world. Global climate models indicate possible global precipitation changes before the end of the century, with an intensity and pattern that depend on the specific climate scenario and are not always consistent between the different models.

Precipitation is a particularly difficult variable, as it is characterized by strong intermittency at all scales and strong orographic dependence, which makes it often hard to model and to measure (see Fig. 1). The measurement of precipitation itself, either by ground stations, radars or satellites, is still a challenging task, which becomes especially hard for solid precipitation at high latitudes or altitudes. These difficulties could hamper efforts to understand and model the hydrological cycle and its variability.

This research task intends to study current and expected changes of precipitation at the global and European scale, with a specific focus on extreme episodes and their effects on mean runoff and intense flooding and drought events.

Groups involved in ECRA participate in the Global Monitoring for Environment and Security (GMES) initiative, which aims at filling in the gaps of the current observing networks, and in the GEO/GEOSS programme.

The methods used in order to achieve the objectives of this task will be data analysis approaches and a host of different modelling methods:

• Data-wise, the focus will be mainly on satellite data and their interpretation, including the problem of precipitation and snow cover retrieval and analysis, and on the study of long historical climatic time series from ground station networks. In particular, satellite data will be instrumental for the definition of water scarcity and drought conditions in connection with global and regional hydrological models in the relatively data sparse areas of the globe.

• At the modelling level, global and regional climate models, mesoscale convective models and stochastic/statistical downscaling procedures, coupled with hydrological models of varying complexity and sub-surface water dynamics will be used and developed. A huge numerical initiative based on the use of high-resolution climate models coupled with global runoff and subsurface flow models will provide new and crucial information on how the global hydrological cycle is changing. Regional climate models nested into the global simulations will allow for focusing on specific climatic hotspots.

Figure 1 shows, as an example, a comparison between different gridded precipitation datasets of different origin (station data, satellite, climate model) for the HKKH area. Notice how the different observational datasets display significant differences from each other.

Figure 1. Multiannual mean (1998-2007) of summer (JJAS) precipitation over the region between 69° and 95°E and 23° and 39°N from the APHRODITE, CRU, GPCC, TRMM, GPCP, ERA-Interim and EC-Earth model datasets. From Palazzi et al., "Precipitation in the Hindu-Kush Karakoram Himalaya: observations and future scenarios", JGR-Atmospheres (2013).

Workshops of the Collaborative Programmes

ECRA member institutions host regular Collaborative Programmes (CP) workshops (1-2 per year). The workshops are coordinated by two chairs of the CP and are supported by the ECRA secretariat. ECRA Workshops serve as platforms for climate scientists to share knowledge and to define the critical future research needs. Workshops are open to all scientists, including those working at ECRA’s member institutions, non-ECRA member institutions, as well as all who may be interested. ECRA workshops are always free of charge and consist of comprehensive science sessions; include presentations of case studies, climate initiatives, and discussions CP strategy, etc. There are typically 20-30 participants.

Each of the Collaborative Programmes (CP) organises workshops on a regular basis.
For further information on the workshop topics, programmes and documentation, see the links below.

CP Arctic [ARC] Workshops	CP High Impact Events [HIE] Workshops	CP Sea Level Change and Coastal Impacts [SLC] Workshops	CP Changes in the Hydrological Cycle [CHC] Workshops

The Arctic climate is changing at a rate, which takes many people – including climate scientists – by surprise. The ongoing and anticipated changes provide vast economic opportunities; but at the same time they pose significant threats to the environment.
ECRA aims to advance Arctic climate research for the benefit of society by raising awareness of key scientific challenges, carrying out coordinated research activities using existing resources, and writing joint proposals to secure external funding for coordinated, cutting edge European polar research and education projects. Arctic ECRA is a network of climate research institutions from different European countries and provides a breadth of expertise including theory, observations, modelling, operational forecasting and logistics.

• Why is Arctic sea ice disappearing so rapidly?
• What are the local and global impacts of Arctic climate change?
• How to advance environmental prediction capabilities for the Arctic and beyond?

Arctic ECRA is open to new participants. The CP is also looking for one or two persons to take on the lead in the future. For any questions, do not hesitate to contact the ECRA Secretariat or the current lead, Lars H. Smedsrud, Bjerknes Centre for Climate Research, NO; This email address is being protected from spambots. You need JavaScript enabled to view it..

 Key Topics

Why is Arctic sea ice disappearing so rapidly?

What are the local and global impacts of Arctic climate change?

How to advance environmental prediction capabilities for the Arctic and beyond?

Workshops

Arctic ECRA has organised three Workshops as well as one Policy Briefing at the European Parliament so far. For further information on the Workshops, please follow this link.

Resources

Arctic ECRA published its Strategy and Work Plan in 2014 that outlines the key research topics to be addressed under this Collaborative Programme as well as strategies to achieve those goals and implementation mechanisms. It is available for download at this link.

A Factsheet presenting key Arctic issues as well as recommendations for research priorities in H2020 and beyond was prepared for ECRA’s General Assembly 2017. It is available for download at this link.

Consider also two reports by the Arctic Monitoring and Assessment Programme: Snow, Water, Ice and Permafrost (SWIPA) summary for policy makers (download) and the report on Adaptation Actions for a changing Arctic (AACA, download).

Coordination

This Collaborative Programme is coordinated by

Lars H. Smedsrud, Bjerknes Centre for Climate Research, NO; This email address is being protected from spambots. You need JavaScript enabled to view it.

Professor, Geophysical Institute, University of Bergen
part of the Bjerknes Centre for Climate Research  (www.bjerknes.uib.no)

Arctic ECRA is currently seeking a new coordinator, and current activities are limited. Much of the coordination that Arctic ECRA used to do is currently taking place within EU-PolarNet (www.eu-polarnet.eu/).
If you would like to participate in coordinating Arctic ECRA please contact the ECRA secretariat.

The rate of global sea level rise accelerated throughout the previous century, with estimates ranging between 1–2 mm/yr for the whole century, and increasing to more than 3 mm/yr for the last couple of decades. Although significant regional differences due to tectonic settings exist, sea level is rising along many coasts worldwide and will continue into the future.
Sea level rise poses a particularly ominous threat to human habitations and infrastructure in the coastal zone: 10% of the world’s population (about 0.7 billion people) live in low-lying coastal regions within 10 m elevation of present-day mean sea level. Sea level rise impacts have been identified as a critical variable for the establishment and maintenance of coastal communities, as a threat to biodiversity and as being responsible for the increasing magnitude and spatial extent of storm surge flood hazard. There are however still large uncertainties regarding the dimensions and timing of the changes to come.
Therefore, more research is needed on methods to assess the effects of climate change, to establish sea level confidence thresholds, to consistently assess future risk of extreme sea level events, and to create and implement adaptation strategies to face the most drastic sea level rise impacts, particularly those associated with low-probability but high-impact changes.
The ECRA Collaborative Programme on Sea Level Change and Coastal Impacts focuses on coastal flooding, regional studies of sea level change, sea level extremes and possible impacts, which is a challenging theme for European research and coastal management. Further key topics are regional context of semi-enclosed basins (e.g. Mediterranean Sea and Baltic Sea), adaptation strategies in a regional context, communication and collaboration between natural, social and economic scientists, stakeholders, policy makers, and the public.

Current key topics include:

• Observations of mean sea level change and contributing processes
• Modelling and projections of regional mean sea level
• Changes in extreme sea levels
• Impacts of sea level changes and adaptation strategies
• Communication and collaboration

The current leads:

Gianmaria Sannino, ENEA, IT: This email address is being protected from spambots. You need JavaScript enabled to view it..

Ingo Sasgen, AWI, DE: This email address is being protected from spambots. You need JavaScript enabled to view it.

See below for more information on the CP, the whitepaper and factsheet.

Key Topics

Observations of mean sea level change and contributing processes

Modelling and projections of regional mean sea level

Changes in extreme sea levels

Impacts of sea level changes and adaptation strategies

Communication and collaboration

Workshops

The CP SLC has organised four Workshops so far. For further information on the Workshops, please follow this link.

Resources

The CP SLC has a White Paper containing information on the CP’s goals and main topics. The current White Paper from December 5, 2016 can be downloaded here.

A Factsheet presenting key issues as well as recommendations for research priorities in H2020 and beyond was prepared for ECRA’s General Assembly 2017. It is available for download at this link.

Coordination

The CP is coordinated by the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), and the Nansen Environmental and Remote Sensing Center (NERSC), and Bjerknes Centre for Climate Research (BCCR), in Norway.

• Gianmaria Sannino: This email address is being protected from spambots. You need JavaScript enabled to view it.
• J. Even Ø. Nilsen: This email address is being protected from spambots. You need JavaScript enabled to view it.

There is an urgent need to increase observations in the Arctic and a demand for open exchange of data in order to improve modelled predictions of future changes. In order to provide a sound basis to stakeholders and politicians for decision making on time scales from days to centuries, it is important to enhance our existing prediction systems.

Arctic ECRA recommends to:

• Understand the role of sea ice and snow cover on seasonal to decadal climate prediction,
• Develop high-resolution models with an improved representation of key Arctic processes (e.g. boundary layer turbulence, double diffusion in the ocean, frazil ice and brine formation, sea ice mechanics),
• Optimise the Arctic observation system for polar prediction purposes,
• Develop data assimilation systems of the coupled Arctic climate system to effectively combine observations and models,
• Represent the forecast uncertainty associated with Arctic key processes in ensemble prediction systems,
• Liaise with the user community to provide relevant forecast products to stakeholders.

The Arctic impacts the rest of the globe in a number of ways: The two most important ones are probably the permafrost thawing, which releases potentially large methane fluxes and thereby increases global warming, and Greenland ice sheet melting, which is now five times higher than in the 1990s and contributes significantly to sea level rise. Ongoing change may additionally open up new economic opportunities for exploitation of fisheries, transportation, rare minerals, oil and gas as well as tourism, all with an expected impact on biodiversity.

Many organisms in the Arctic Ocean are highly adapted to an older and thicker sea ice regime or temperatures close to freezing, leaving them and the Arctic ecosystem vulnerable to the ongoing warming. They are presently being pushed northward on the shelves and down the slopes where only deep-water species are able to survive. At the same time, species from the South are spreading into previously ice-covered areas and might compete with Arctic species for food and space.

There is growing concern about the rapid climatic changes occurring in the Arctic and the impact of these changes for future development of the European and global climate have to be understood. For planning and managing purposes it is crucial to obtain a comprehensive quantitative understanding of the past, present and future impacts of Arctic climate change.

It is therefore recommended to support research that:

• Provides a comprehensive understanding of the local impacts of global significance of Arctic climate change. Aspects to be considered include: Sea ice, snow cover, and Greenland ice sheets; Permafrost and methane release; and Ecosystems.
• Provides a thorough understanding of the consequences of Arctic climate change on Europe and the world.