Arctic and Baltic sea ice

Assessment versions

Published (reviewed and quality assured)

• 08 Dec 2020, 02:39 PM
  - Arctic and Baltic sea ice

Rationale

Justification for indicator selection

The changes observed in the extent of sea ice provide evidence of global warming. Reduced Arctic sea ice is accelerating global warming through ice-albedo feedback. Several studies also suggest causal links between Arctic sea ice decline and summer precipitation in Europe, the Mediterranean and East Asia. Reduced Arctic ice cover may also lead to increases in heavy snowfall in Europe during early winter.

The projected loss of sea ice may offer new economic opportunities for oil and gas exploration, shipping, tourism and some types of fisheries in the Arctic. Most of these activities would increase the pressure on, and the risks to, the Arctic environment.

Scientific references

• Blunden, J. and Arndt, D. S., eds., 2020, ‘State of the Climate in 2019’, Bulletin of the American Meteorological Society 101(8), pp. S1-S429 (DOI: 10.1175/2020BAMSStateoftheClimate.1)
• Coumou, D., et al., 2018, ‘The influence of Arctic amplification on mid-latitude summer circulation’, Nature Communications 9(1), p. 2959 (DOI: 10.1038/s41467-018-05256-8).
• Haapala, J. J., et al., 2015, ‘Recent change - Sea ice’ The BACC II Author Team (ed.), Second assessment of climate change for the Baltic Sea basin, Springer International Publishing, Cham, pp. 145-153.
• Hezel, P. J., et al., 2014, ‘Modeled Arctic sea ice evolution through 2300 in CMIP5 extended RCPs’, The Cryosphere 8(4), pp. 1195-1204 (DOI: 10.5194/tc-8-1195-2014).
• Jahn, A., 2018, ‘Reduced probability of ice-free summers for 1.5 °C compared to 2 °C warming’, Nature Climate Change 8(5), pp. 409-413 (DOI: 10.1038/s41558-018-0127-8)
• Luomaranta, A., et al., 2014, ‘Multimodel estimates of the changes in the Baltic Sea ice cover during the present century’, Tellus A 66(22617) (DOI: 10.3402/tellusa.v66.22617).
• Meredith, M., et al., 2019, ‘Chapter 3: Polar Regions’ Pörtner, H.-O. et al. (eds), IPCC Special Report on the Ocean and Cryosphere in a Changing Climate, Cambridge University Press, Cambridge, UK.
• Schweiger, A. J., et al., 2019, ‘Arctic Sea Ice Volume Variability over 1901–2010: A Model-Based Reconstruction’ Journal of Climate32(15), pp. 4731-4752 (DOI: 10.1175/JCLI-D-19-0008.1).
• Sigmond, M., et al., 2018, ‘Ice-free Arctic projections under the Paris Agreement Nature Climate Change 8(5), pp. 404-408 (DOI: 10.1038/s41558-018-0124-y).
• SIMIP Community, 2020, ‘Arctic Sea Ice in CMIP6’ Geophysical Research Letters 47(10) (DOI: 10.1029/2019GL086749).
• Vihma, T., 2014, ‘Effects of Arctic sea ice decline on weather and climate: A review’  Surveys in Geophysics35(5), pp. 1175-1214 (DOI: 10.1007/s10712-014-9284-0).
• Walsh, J. E., et al., 2017, ‘A database for depicting Arctic sea ice variations back to 1850’ Geographical Review 107(1), pp. 89-107 (DOI: 10.1111/j.1931-0846.2016.12195.x)
• Lavergne, T. et al., 2019: 'Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records' The Cryosphere, 13, 49–78 (DOI:10.5194/tc-13-49-2019).

Indicator definition

This indicator shows trends in the area of Arctic sea ice in March (annual ice maximum) and September (annual ice minimum). Satellite observations cover the period from 1979 until now. Projections until 2100 are based on an ensemble of climate models from the CMIP6 exercise, which informs the Intergovernmental Panel on Climate Change Sixth Assessment Report. Note that earlier versions of this indicator have shown the extent rather than the area of Artic sea ice, which is closely related, but can lead to somewhat different numbers.

The indicator also shows observations of maximum annual ice extent in the Baltic sea, reaching back to 1719.

Units

Policy context and targets

Context description

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Targets

No targets have been specified.

Related policy documents

No related policy documents have been specified

Methodology

Methodology for indicator calculation

Observations of Arctic sea ice were available from the EUMETSAT OSI SAF reanalysis project, in which a consistent time series of daily, gridded data for sea ice concentration is made from the passive microwave sensors SMMR and SSM/I data. Monthly aggregated sea ice products are provided by the EUMETSAT OSI SAF. Projections for Arctic sea ice area were derived from the CMIP6 ensemble experiment.

The annual maximum ice extent in the Baltic Sea was estimated based on three sources. Ice extent for the winters of 1720-1940 is based on a construction from various sources, including observations at lighthouses, old newspapers, records of travel on ice, scientific articles, and air temperature data from Stockholm and Helsinki. Data for 1945-1995 stems from the Finnish operational ice service. Data since 1995 is based on satellite observations.

The graphs show the data as delivered; linear trend lines and moving averages were added.

Methodology for gap filling

Not applicable.

Methodology references

No methodology references available.

Data specifications

EEA data references

• No datasets have been specified here.

External data references

• Arctic monthly mean sea ice area
• Arctic sea ice area for the 21st century from CMIP6 simulations (Dataset URL is not available)
• Baltic Sea - Sea Ice Concentration and Thickness Charts
• Maximum annual extent of ice cover in the Baltic Sea

Data sources in latest figures

Uncertainties

Methodology uncertainty

Not applicable

Data sets uncertainty

No uncertainty has been specified

Rationale uncertainty

No uncertainty has been specified