Indicator Specification

Lake and river ice cover

Indicator Specification
  Indicator codes: CLIM 020
Published 08 Sep 2008 Last modified 03 Feb 2017
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Ice break-up dates from selected European lakes and rivers (1835-2006) and the North Atlantic Oscillation (NAO) index for winter 1864-2006

Update planned for November 2012

Assessment versions

Published (reviewed and quality assured)
  • No published assessments


Justification for indicator selection

The appearance of ice on lakes and rivers requires prolonged periods with air temperatures below 0 oC. The deeper the lake, the more cold is needed to cool down the lake so that ice forms. Higher temperatures will affect the duration of ice cover, the freezing and thawing dates and the thickness of the ice cover.
Changes in ice cover are of critical ecological importance for lakes because of their effect on the underwater light levels (Lepparanta et al., 2003), nutrient recycling (Jarvinen et al., 2002) and oxygen conditions (Stewart, 1976; Livingstone, 1993), which influence the production and biodiversity of phytoplankton (Rodhe, 1955; Phillips and Fawley, 2002; Weyhenmeyer et al., 1999), and the occurrence of winter fish kills (Greenbank, 1945; Barica and Mathias, 1979). Less ice may in some cases result in reduced fish kills.
Changes in lake and river ice may affect winter transportation, bridge and pipeline crossings, and winter sports but no quantitative evidence for such effects yet exists (IPCC, 2007). In Europe there is some evidence of a reduction in ice-jam floods due to reduced freshwater freezing during the last century (Svensson et al., 2006).

Scientific references

  • No rationale references available

Indicator definition

  • Ice break-up dates from selected European lakes and rivers (1835-2006) and the North Atlantic Oscillation (NAO) index for winter 1864-2006



Policy context and targets

Context description

In April 2009 the European Commission presented a White Paper on the framework for adaptation policies and measures to reduce the European Union's vulnerability to the impacts of climate change. The aim is to increase the resilience to climate change of health, property and the productive functions of land, inter alia by improving the management of water resources and ecosystems. More knowledge is needed on climate impact and vulnerability but a considerable amount of information and research already exists which can be shared better through a proposed Clearing House Mechanism. The White Paper stresses the need to mainstream adaptation into existing and new EU policies. A number of Member States have already taken action and several have prepared national adaptation plans. The EU is also developing actions to enhance and finance adaptation in developing countries as part of a new post-2012 global climate agreement expected in Copenhagen (Dec. 2009). For more information see:


No targets have been specified

Related policy documents

No related policy documents have been specified



Methodology for indicator calculation

Methodology for gap filling

Methodology references

No methodology references available.


Data specifications

EEA data references

  • No datasets have been specified here.

External data references

Data sources in latest figures



Methodology uncertainty

Data sets uncertainty

Rationale uncertainty

No uncertainty has been specified

Further work

Short term work

Work specified here requires to be completed within 1 year from now.

Long term work

Work specified here will require more than 1 year (from now) to be completed.

General metadata

Responsibility and ownership

EEA Contact Info

Peter Kristensen


European Environment Agency (EEA)


Indicator code
CLIM 020
Version id: 1


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


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