Arctic sea ice has declined at a rapid rate since the 1990s. Summer sea ice extent has declined by about 50% and sea ice thickness by about 40%. Arctic sea ice has thus moved into a new, more vulnerable regime with predominance of first-year ice, longer periods of open water, and enhanced surface melt rates. But – the Arctic is also subject to large natural variability, especially in the Atlantic sector; and a number of non-linear feedbacks play an important role in both enhancing and dampening the ice loss.

The mismatch between expected and observed rates of Arctic climate change is most clearly reflected by the fact that despite the progress, climate models are still unable to predict critical aspects of sea ice changes and their timing. This mismatch highlights the gap in our understanding of the underlying processes and feed- backs, as well as their realistic representation in climate models.

To ensure progress, Arctic ECRA recommends to:

• Maintain and enhance our European multi-disciplinary monitoring capabilities, which have been effective at detecting recent changes,
• Carry out dedicated joint observational and modelling campaigns to gain a better understanding of climate-relevant processes and ensure their accurate representation in climate models,
• Study natural variability of the Arctic climate system and its representation by models,
• Provide more reliable Arctic climate change predictions and projections to stakeholders based on the output of improved climate models, and
• Develop schemes that provide improved information of climate change uncertainty.
• Conduct further research into decadal scale variability to make reliable future predictions of Arctic sea ice

So far activities have been introduced and discussed at a pilot workshop in Utrecht 2012. A second workshop took place in Hamburg 2013, and we sponsored the sea level workshop in Mallorca 2015 and had a SL-CP meeting preceding the workshop:

5th Meeting | 11 July 2017 | New York City | USA

Pilot Workshop | 14-16 March 2012 | Utrecht, The Netherlands

2nd Workshop | 20-22 November 2013 | Hamburg, Germany

3rd Workshop | 10-12 June 2015 | Palma, Spain

4th Workshop | 21-22 June 2016 | Bergen, Norway

The Collaborative Programme High Impact Events has organised three workshops up until now:

• Pilot Workshop | 14-15 June 2012 | Cambridge, UK
• 2nd Workshop | 3-4 June 2013 | Bergen, Norway
• 3rd Workshop | 2-3 June 2014 | Copenhagen, Denmark

There is growing awareness that climate change cannot solely be considered as a “mean state” modification. The impacts of climate change are closely tied to regional and local conditions. Changes in the characteristics, frequency, and severity of extreme weather events are amongst the most significant aspects of climate change. To understand and predict such events, which are typically responsible for the most disastrous climate impacts, is of paramount importance. Not all extremes lead to high impacts. However, high impact events are conditioned based on the exposure and vulnerability of particular regions or locations. Different types of extremes, e.g. droughts and extreme precipitation, might be associated with different regions.

This Collaborative Programme examines how high impact events work, how they can be simulated accurately in numerical models and how we might be able to project future changes reliably, highlighting the important regional differences regarding their impacts. As such, high resolution climate and impact modelling as well as downscaling with different methodologies are among the key issues. The CP further focuses on climate risk analysis, vulnerability and adaptation.

We work based on a list of science topics. The science topics can be adjusted and allow flexible participation of ECRA and non-ECRA partners. The general strategy starts from fundamental physical concepts, continues via process understanding and goes towards the best possible numerical simulations of the global and regional changes of extreme events, including composition-climate interactions, feedback and impacts.

Key topics

Understanding mechanisms:
Assessment of past and future high impact events

Projecting changes:
High resolution climate and impact modelling

Producing climate information at relevant scales:
Downscaling with different methodologies

Co-creating climate services with users:
Climate risk analysis, vulnerability and adaptation

Collaboration (Projects/Initiatives)

This CP has organised side events at the International Conference on Regional Climate (ICRC)-CORDEX and joint Workshops with the ECRA CP Changes in the Hydrological Cycle (see below).

Workshops

The CP HIE has organised three Workshops so far and two joint Workshops together with the CP Changes in the Hydrological Cycle.

For further information on the Workshops, please follow this link.

Resources

The CP HIE has a White Paper containing information on the CP’s general scope, activities and an implementation plan. The current White Paper from 2014 (working document) is available for download at this link.

An Introduction Brochure to the Collaborative Programme has been published in March 2015 and is available for download here (pdf).

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 here.

Coordination

The CP is coordinated by

Hilppa Gregow: This email address is being protected from spambots. You need JavaScript enabled to view it. (Finnish Meteorological Institute)

Martin Drews: This email address is being protected from spambots. You need JavaScript enabled to view it. (Danmarks Tekniske Universitet)

Please contact the secretariat for information (e.g. Mailinglist)

The global hydrological cycle includes many different components reacting in complex, dynamic and often non-linear ways to external forcings such as, but not limited to, climate change. While hydrological impacts of climate change – e.g. spatial and temporal alterations in water balance, streamflow and extreme events (floods, droughts) - typically occur at regional or local scales, they can trigger modifications that lead to larger-scale or even global changes in the water cycle.

This Collaborative Programme aims at improving the scientific understanding of hydrological processes under modified climatic boundary conditions and at studying possible impacts of changing hydrological cycle components (precipitation, runoff, snow, etc) on the environment and the society. Meeting emerging societal challenges, in fact, is another aspect this CP intends to address.

Current key topics of the CHC—CP include:

• Global precipitation changes and runoff. 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. Using observations and (global to hydrological) model simulations, this research task studies 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.
• Interaction between climate and hydrological/land surface processes. Modifications of the water cycle significantly affect land surface properties and ecosystem functioning and are at the same time driven by changes in vegetation and land surface changes. In order to better understand these complex interactions, this CP uses a hierarchy of models working at different spatial and temporal resolutions, compared to/validated against in-situ and EO data.
• Climate hot spot regions: Mediterranean region and Global Mountains. The Mediterranean basin and mountains areas are among the regions which are referred to as “climate change hot-spots”. In these regions climate change signals are amplified, as are their possible effects. Studying these areas would allow to develop appropriate adaptation and mitigation measures in the coming decades.
• Societal challenges related to impact of changes in the hydrological cycle. Among the expected impacts of observed and projected changes in the hydrological cycle are the lack of water for drinking, agriculture, industry and energy production, which imposes risks for civil security. Impact-oriented research aims at effectively responding to crucial societal challenges resulting from changes in different components the hydrological cycle and to support adaptation and risk mitigation strategies. 

See below for more information on the CP structure and tasks, and a factsheet summarizing the CP. A White paper delineating activities and presenting the grand challenges is in preparation and will be published in early 2019.

research topics

Global precipitation changes and runoff

Interaction between climate and hydrological/land surface processes

Climate hot spot regions: Mediterranean region and Global Mountains

Societal challenges related to impact of changes in the hydrological cycle

Collaboration (Projects/Initiatives)

For this, the research groups and institutions involved in ECRA collaborate with other European and international scientific initiatives, such as the Belmont Forum with its Collaborative Research Actions (CRAs), the Mountain Research Initiative (MRI) and collaborations with existing national and international projects, e.g. the EU H2020 projects ECOPOTENTIAL, CRESCENDO and PRIMAVERA. New proposals and joint actions will be developed during the research activities.

Workshops

The CP Changes in the Hydrological Cycle has organised three Workshops, two joint Workshops together with the CP High Impact Events as well as one Policy Briefing at the European Parliament so far. For further information on the Workshops, please follow this link.

Resources

The Hydrological Cycle Briefing Document (March 2015) includes a Special Focus on “The changing mountains of Europe – Water resources and ecosystems at risk”. It will be made available for download here soon.

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 here.

Coordination

Coordinated by:

Ralf Ludwig, Ludwig-Maximilians-University Munich, DE, This email address is being protected from spambots. You need JavaScript enabled to view it.

Lisa Palazzi, National Research Council of Italy (CNR), IT, This email address is being protected from spambots. You need JavaScript enabled to view it.

Collaborative Programmes (CPs) represent ECRA core activities. The CPs are collaborative efforts of ECRA partners, aiming to identify key research topics of high scientific relevance, and to establish new frameworks of coordinated international research. CP outputs are promulgated through publications, i.e. whitepapers and work plans.

A CP may be subdivided into working groups depending on its scope. These sub-groups would have research goals and milestones complementary to the overall research goals of the CP, and could include a number of collaborative projects or activities.

There are currently four major research topics synonymous with ECRA CPs:

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

Workshops of the Collaborative Programmes

ECRA member institutions host regular CP Workshops (1-2 per year). The workshops are coordinated by one or 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.

	Arctic Climate Stability and Changes Coordinated by the Bjerknes Centre for Climate Research, NO
	High Impact Events and Climate Change Coordinated by the Karlsruhe Institute for Technology (KIT), DE with input from the National Centre for Atmospheric Science (NCAS), UK and the Technical University of Denmark (DTU), DK
	Sea Level Change and Coastal Impacts Coordinated by the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), IT and the Nansen Environmental and Remote Sensing Center (NERSC), NO
	Changes in the Hydrological Cycle Coordinated by the National Research Council of Italy (CNR), IT and the Ludwig-Maximilians-University Munich, DE