Heavy precipitation

Indicator Assessment
Prod-ID: IND-92-en
Also known as: CLIM 004
Created 04 Jan 2017 Published 04 Jan 2017 Last modified 04 Jan 2017
14 min read
The intensity of heavy precipitation events in summer and winter have increased in northern and north-eastern Europe since the 1960s. Different indices show diverging trends for south-western and southern Europe. Heavy precipitation events are likely to become more frequent in most parts of Europe. The projected changes are strongest in Scandinavia and eastern Europe in winter.

Key messages

  • The intensity of heavy precipitation events in summer and winter have increased in northern and north-eastern Europe since the 1960s. Different indices show diverging trends for south-western and southern Europe.
  • Heavy precipitation events are likely to become more frequent in most parts of Europe. The projected changes are strongest in Scandinavia and eastern Europe in winter.

What are the past trends and projected changes in heavy precipitation events across Europe?

Projected changes in heavy precipitation in winter and summer

Note: Projected changes in heavy precipitation (in %) in winter and summer from 1971-2000 to 2071–2100 for the RCP8.5 scenario based on the ensemble mean of different regional climate models (RCMs) nested in different general circulation models (GCMs).

Data source:
Downloads and more info

Past trends

The majority of observation-based studies that investigate trends in extreme rainfall intensity are based on data recorded at the daily time scale. An index for the maximum annual precipitation over five consecutive days (Rx5d) shows significant increases up to 5 mm per decade over northern and north-western Europe in winters and up to 4 mm in summers (Figure 1 left). The same index shows decreases of more than 5 mm per decade in south-western Europe in winter and between 2 and 3 mm in summer (Figure 1 right). The smaller trends in central and south-eastern Europe are not statistically significant. The increase in northern and north-eastern Europe is a consequence of the observed shift polewards of the North Atlantic storm track and weakening of Mediterranean storms [i].

A wider literature review suggests that heavy precipitation events have become more intense and more frequent in Europe on average, but there are important differences across regions, seasons, time periods, heavy precipitation indices and underlying datasets. Studies generally agree that heavy precipitation has become more intense in northern and north-eastern Europe since the 1950s, even though not all changes are statistically significant. Different studies and indices show diverging trends for south-western and southern Europe.

Records of daily mean precipitation are often insufficient to study trends and changes in heavy precipitation. The damage associated with heavy precipitation often originates from sub-daily localised heavy precipitation events, which can lead to costly flash floods. Owing to limited data availability, only a limited number of studies have focused on large regional scale assessments of sub-daily precipitation [ii]. A recent review study concludes that extreme sub-daily precipitation events have generally increased in Europe, even in regions with decreases in mean rainfall, but there is large variability across regions, seasons and event durations [iii].

Projections

Global warming is projected to lead to a higher intensity of precipitation and longer dry periods in Europe [iv]. Projections show an increase in heavy daily precipitation in most parts of Europe in winter, by up to 35 % during the 21st century. Heavy precipitation in winter is projected to increase over most of Europe, with increases of up to 30 % in north-eastern Europe (Figure 2 left). In summer, an increase is also projected in most parts of Europe, but decreases are projected for some regions in southern and south-western Europe (Figure 2 right) [v]. Similar patterns were found for other heavy precipitation indices [vi].

The continued increase in the spatial and temporal resolution of global and regional climate models has generally improved the representation of extreme precipitation and increased confidence in model-based projections [vii]. However, regional climate models with spatial resolutions of between 10 and 30 km typically used in climate change studies are still too coarse to explicitly represent sub-daily localised heavy precipitation events [viii]. Evidence from high-resolution climate models suggests that the intensity of sub-daily extreme rainfall is likely to increase in the future, whereby an increase of (theoretically estimated) ~7 % per °C appears most likely in many regions [ix]. A very high-resolution model (typically 1–5 km) used for weather forecasts with explicit convection has recently been used for a climate change experiment for a region in the United Kingdom. This study projects intensification of short-duration heavy rain in the summer, with significantly more events exceeding the high thresholds indicative of serious flash flooding [x].



[i] Øystein Hov et al., “Extreme Weather Events in Europe: Preparing for Climate Change Adaptation” (Oslo: Norwegian Meteorological Institute, 2013), http://www.dnva.no/binfil/download.php?tid=58783.

[ii] D. L. Hartmann et al., “Observations: Atmosphere and Surface,” inClimate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, ed. T. F. Stocker et al. (Cambridge; New York: Cambridge University Press, 2013), Chapter 2, http://www.climatechange2013.org/report/full-report/.

[iii] S. Westra et al., “Future Changes to the Intensity and Frequency of Short-Duration Extreme Rainfall,”Reviews of Geophysics 52, no. 3 (September 1, 2014): 2014RG000464, doi:10.1002/2014RG000464.

[iv] IPCC,Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. Special Report of the Intergovernmental Panel on Climate Change (Cambridge: Cambridge University Press, 2012), http://ipcc-wg2.gov/SREX/report/; Hov et al., “Extreme Weather Events in Europe: Preparing for Climate Change Adaptation.”

[v] Daniela Jacob et al., “EURO-CORDEX: New High-Resolution Climate Change Projections for European Impact Research,”Regional Environmental Change 14, no. 2 (2014): 563–78, doi:10.1007/s10113-013-0499-2.

[vi] J. Rajczak, P. Pall, and C. Schär, “Projections of Extreme Precipitation Events in Regional Climate Simulations for Europe and the Alpine Region,”Journal of Geophysical Research: Atmospheres 118, no. 9 (2013): 3610–26, doi:10.1002/jgrd.50297; J. Sillmann et al., “Climate Extremes Indices in the CMIP5 Multimodel Ensemble. Part 2: Future Climate Projections,”Journal of Geophysical Research: Atmospheres 118, no. 6 (March 27, 2013): 2473–93, doi:10.1002/jgrd.50188; F. Giorgi, E. Coppola, and F. Raffaele, “A Consistent Picture of the Hydroclimatic Response to Global Warming from Multiple Indices: Models and Observations,”Journal of Geophysical Research: Atmospheres 119, no. 20 (Oktober 2014): 2014JD022238, doi:10.1002/2014JD022238.

[vii] Pushkar Kopparla et al., “Improved Simulation of Extreme Precipitation in a High-Resolution Atmosphere Model,”Geophysical Research Letters 40, no. 21 (November 16, 2013): 5803–8, doi:10.1002/2013GL057866; Filippo Giorgi et al., “Changes in Extremes and Hydroclimatic Regimes in the CREMA Ensemble Projections,”Climatic Change 125, no. 1 (April 12, 2014): 39–51, doi:10.1007/s10584-014-1117-0; Myriam Montesarchio et al., “Performance Evaluation of High-Resolution Regional Climate Simulations in the Alpine Space and Analysis of Extreme Events,”Journal of Geophysical Research: Atmospheres 119, no. 6 (March 27, 2014): 2013JD021105, doi:10.1002/2013JD021105.

[viii] Steven C. Chan et al., “The Value of High-Resolution Met Office Regional Climate Models in the Simulation of Multihourly Precipitation Extremes,”Journal of Climate 27, no. 16 (March 21, 2014): 6155–74, doi:10.1175/JCLI-D-13-00723.1; Nikolina Ban, Juerg Schmidli, and Christoph Schär, “Heavy Precipitation in a Changing Climate: Does Short-Term Summer Precipitation Increase Faster?,”Geophysical Research Letters 42, no. 4 (February 28, 2015): 2014GL062588, doi:10.1002/2014GL062588.

[ix] Westra et al., “Future Changes to the Intensity and Frequency of Short-Duration Extreme Rainfall.”

[x] Elizabeth J. Kendon et al., “Heavier Summer Downpours with Climate Change Revealed by Weather Forecast Resolution Model,”Nature Climate Change 4, no. 7 (June 1, 2014): 570–76, doi:10.1038/nclimate2258; Ban, Schmidli, and Schär, “Heavy Precipitation in a Changing Climate”; Jascha Lehmann, Dim Coumou, and Katja Frieler, “Increased Record-Breaking Precipitation Events under Global Warming,”Climatic Change 132, no. 4 (July 7, 2015): 501–15, doi:10.1007/s10584-015-1434-y.

Indicator specification and metadata

Indicator definition

Heavy precipitation is defined as the maximum annual five-day consecutive precipitation. Trends are calculated for the period between 1960 and 2015.

Projected changes in heavy precipitation are defined as changes in the 95th percentile of daily precipitation (only days with precipitation >1 mm/day are considered). Changes between two periods 1971-2000 and 2071-2100 are calculated by using a multi-model ensemble forced by RCP8.5.

Units

  • Trends in heavy precipitation (mm/decade)
  • Changes in projected heavy precipitation (%)

Policy context and targets

Context description

In April 2013 the European Commission presented the EU Adaptation Strategy Package (http://ec.europa.eu/clima/policies/adaptation/what/documentation_en.htm). This package consists of the EU Strategy on adaptation to climate change /* COM/2013/0216 final */ and a number of supporting documents. One of the objectives of the EU Adaptation Strategy is Better informed decision-making, which should occur through Bridging the knowledge gap and Further developing Climate-ADAPT as the ‘one-stop shop’ for adaptation information in Europe. Further objectives include Promoting action by Member States and Climate-proofing EU action: promoting adaptation in key vulnerable sectors. Many EU Member States have already taken action, such as by adopting national adaptation strategies, and several have also prepared action plans on climate change adaptation.

The European Commission and the European Environment Agency have developed the European Climate Adaptation Platform (Climate-ADAPT, http://climate-adapt.eea.europa.eu/) to share knowledge on observed and projected climate change and its impacts on environmental and social systems and on human health; on relevant research; on EU, national and subnational adaptation strategies and plans; and on adaptation case studies.

In September 2016, the EC presented an indicative roadmap for the evaluation of the EU Adaptation Strategy by 2018.

In November 2013, the European Parliament and the European Council adopted the 7th EU Environment Action Programme (7th EAP) to 2020, ‘Living well, within the limits of our planet’. The 7th EAP is intended to help guide EU action on environment and climate change up to and beyond 2020. It highlights that ‘Action to mitigate and adapt to climate change will increase the resilience of the Union’s economy and society, while stimulating innovation and protecting the Union’s natural resources.’ Consequently, several priority objectives of the 7th EAP refer to climate change adaptation.

Targets

No targets have been specified.

Related policy documents

  • 7th Environment Action Programme
    DECISION No 1386/2013/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 20 November 2013 on a General Union Environment Action Programme to 2020 ‘Living well, within the limits of our planet’. In November 2013, the European Parliament and the European Council adopted the 7 th EU Environment Action Programme to 2020 ‘Living well, within the limits of our planet’. This programme is intended to help guide EU action on the environment and climate change up to and beyond 2020 based on the following vision: ‘In 2050, we live well, within the planet’s ecological limits. Our prosperity and healthy environment stem from an innovative, circular economy where nothing is wasted and where natural resources are managed sustainably, and biodiversity is protected, valued and restored in ways that enhance our society’s resilience. Our low-carbon growth has long been decoupled from resource use, setting the pace for a safe and sustainable global society.’
  • Climate-ADAPT: Mainstreaming adaptation in EU sector policies
    Overview of EU sector policies in which mainstreaming of adaptation to climate change is ongoing or explored
  • Climate-ADAPT: National adaptation strategies
    Overview of activities of EEA member countries in preparing, developing and implementing adaptation strategies
  • DG CLIMA: Adaptation to climate change
    Adaptation means anticipating the adverse effects of climate change and taking appropriate action to prevent or minimise the damage they can cause, or taking advantage of opportunities that may arise. It has been shown that well planned, early adaptation action saves money and lives in the future. This web portal provides information on all adaptation activities of the European Commission.
  • EU Adaptation Strategy Package
    In April 2013, the European Commission adopted an EU strategy on adaptation to climate change, which has been welcomed by the EU Member States. The strategy aims to make Europe more climate-resilient. By taking a coherent approach and providing for improved coordination, it enhances the preparedness and capacity of all governance levels to respond to the impacts of climate change.

Methodology

Methodology for indicator calculation

Observed heavy precipitation is defined as maximum precipitation over five consecutive days (Rx5d). Ensemble of RCMs driven by different GCMs all using RCP8.5 scenario has been used to calculate changes in heavy precipitation and dry spells.

Projected heavy precipitation is defined as the 95th percentile of daily precipitation (only days with precipitation >1 mm/day are considered).

Trends are calculated using a median of pairwise slopes algorithm. Black dots represent high confidence in the sign of the long-term trend in the box (if the 5th to 95th percentile slopes are of the same sign). Boxes which have a thick outline contain at least three stations.

Methodology for gap filling

To accurately assess trends in heavy precipitation at local scales, high-resolution datasets are required. These climatological datasets are compiled from the observation networks from countries and additional data from regional observations networks. As some countries do not share all of their datasets, the spatial and temporal coverage of the European dataset, and consequently the accuracy of past trends, varies across Europe.

However, even where sufficient data are available, several problems can limit their use for analysis. These problems are mainly connected with 1) limitations of distributing data in high spatial and temporal resolution by many countries, 2) unavailability of data in easy-to-use digital format, and lack of data homogeneity.

Methodology references

Uncertainties

Methodology uncertainty

See under "Methodology".


Data sets uncertainty

The risks posed by precipitation-related hazards, such as flooding events (including flash floods) and landslides, are also influenced by non-climatic factors, such as population density, floodplain development and land-use change. Hence, estimates of future changes in such risks need to consider changes in both climatic and non-climatic factors. Estimates of trends in heavy or extreme precipitation are more uncertain than trends in mean precipitation because, by their very nature, extreme precipitation events have a low frequency of occurrence. This leads to greater uncertainties when assessing the statistical significance of observed changes.


Rationale uncertainty

No uncertainty has been specified

Data sources

Generic metadata

Topics:

information.png Tags:
, ,
DPSIR: Impact
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)

Contacts and ownership

EEA Contact Info

Blaz Kurnik

EEA Management Plan

2016 1.4.1 (note: EEA internal system)

Dates

Frequency of updates

Updates are scheduled every 4 years
European Environment Agency (EEA)
Kongens Nytorv 6
1050 Copenhagen K
Denmark
Phone: +45 3336 7100