Sea-ice indicators of polar bear habitat
Nineteen subpopulations of polar bears ( Ursus maritimus ) are found throughout the circumpolar Arctic, and in all regions they depend on sea ice as a platform for traveling, hunting, and breeding. Therefore polar bear phenology – the cycle of biological events – is linked to the timing of sea-ice r...
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ftcopernicus:oai:publications.copernicus.org:tc51236 2023-05-15T14:29:12+02:00 Sea-ice indicators of polar bear habitat Stern, Harry L. Laidre, Kristin L. 2018-09-27 application/pdf https://doi.org/10.5194/tc-10-2027-2016 https://tc.copernicus.org/articles/10/2027/2016/ eng eng doi:10.5194/tc-10-2027-2016 https://tc.copernicus.org/articles/10/2027/2016/ eISSN: 1994-0424 Text 2018 ftcopernicus https://doi.org/10.5194/tc-10-2027-2016 2020-07-20T16:23:59Z Nineteen subpopulations of polar bears ( Ursus maritimus ) are found throughout the circumpolar Arctic, and in all regions they depend on sea ice as a platform for traveling, hunting, and breeding. Therefore polar bear phenology – the cycle of biological events – is linked to the timing of sea-ice retreat in spring and advance in fall. We analyzed the dates of sea-ice retreat and advance in all 19 polar bear subpopulation regions from 1979 to 2014, using daily sea-ice concentration data from satellite passive microwave instruments. We define the dates of sea-ice retreat and advance in a region as the dates when the area of sea ice drops below a certain threshold (retreat) on its way to the summer minimum or rises above the threshold (advance) on its way to the winter maximum. The threshold is chosen to be halfway between the historical (1979–2014) mean September and mean March sea-ice areas. In all 19 regions there is a trend toward earlier sea-ice retreat and later sea-ice advance. Trends generally range from −3 to −9 days decade −1 in spring and from +3 to +9 days decade −1 in fall, with larger trends in the Barents Sea and central Arctic Basin. The trends are not sensitive to the threshold. We also calculated the number of days per year that the sea-ice area exceeded the threshold (termed ice-covered days) and the average sea-ice concentration from 1 June through 31 October. The number of ice-covered days is declining in all regions at the rate of −7 to −19 days decade −1 , with larger trends in the Barents Sea and central Arctic Basin. The June–October sea-ice concentration is declining in all regions at rates ranging from −1 to −9 percent decade −1 . These sea-ice metrics (or indicators of habitat change) were designed to be useful for management agencies and for comparative purposes among subpopulations. We recommend that the National Climate Assessment include the timing of sea-ice retreat and advance in future reports. Text Arctic Basin Arctic Barents Sea Sea ice Ursus maritimus Copernicus Publications: E-Journals Arctic Barents Sea The Cryosphere 10 5 2027 2041 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
Nineteen subpopulations of polar bears ( Ursus maritimus ) are found throughout the circumpolar Arctic, and in all regions they depend on sea ice as a platform for traveling, hunting, and breeding. Therefore polar bear phenology – the cycle of biological events – is linked to the timing of sea-ice retreat in spring and advance in fall. We analyzed the dates of sea-ice retreat and advance in all 19 polar bear subpopulation regions from 1979 to 2014, using daily sea-ice concentration data from satellite passive microwave instruments. We define the dates of sea-ice retreat and advance in a region as the dates when the area of sea ice drops below a certain threshold (retreat) on its way to the summer minimum or rises above the threshold (advance) on its way to the winter maximum. The threshold is chosen to be halfway between the historical (1979–2014) mean September and mean March sea-ice areas. In all 19 regions there is a trend toward earlier sea-ice retreat and later sea-ice advance. Trends generally range from −3 to −9 days decade −1 in spring and from +3 to +9 days decade −1 in fall, with larger trends in the Barents Sea and central Arctic Basin. The trends are not sensitive to the threshold. We also calculated the number of days per year that the sea-ice area exceeded the threshold (termed ice-covered days) and the average sea-ice concentration from 1 June through 31 October. The number of ice-covered days is declining in all regions at the rate of −7 to −19 days decade −1 , with larger trends in the Barents Sea and central Arctic Basin. The June–October sea-ice concentration is declining in all regions at rates ranging from −1 to −9 percent decade −1 . These sea-ice metrics (or indicators of habitat change) were designed to be useful for management agencies and for comparative purposes among subpopulations. We recommend that the National Climate Assessment include the timing of sea-ice retreat and advance in future reports. |
format |
Text |
author |
Stern, Harry L. Laidre, Kristin L. |
spellingShingle |
Stern, Harry L. Laidre, Kristin L. Sea-ice indicators of polar bear habitat |
author_facet |
Stern, Harry L. Laidre, Kristin L. |
author_sort |
Stern, Harry L. |
title |
Sea-ice indicators of polar bear habitat |
title_short |
Sea-ice indicators of polar bear habitat |
title_full |
Sea-ice indicators of polar bear habitat |
title_fullStr |
Sea-ice indicators of polar bear habitat |
title_full_unstemmed |
Sea-ice indicators of polar bear habitat |
title_sort |
sea-ice indicators of polar bear habitat |
publishDate |
2018 |
url |
https://doi.org/10.5194/tc-10-2027-2016 https://tc.copernicus.org/articles/10/2027/2016/ |
geographic |
Arctic Barents Sea |
geographic_facet |
Arctic Barents Sea |
genre |
Arctic Basin Arctic Barents Sea Sea ice Ursus maritimus |
genre_facet |
Arctic Basin Arctic Barents Sea Sea ice Ursus maritimus |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-10-2027-2016 https://tc.copernicus.org/articles/10/2027/2016/ |
op_doi |
https://doi.org/10.5194/tc-10-2027-2016 |
container_title |
The Cryosphere |
container_volume |
10 |
container_issue |
5 |
container_start_page |
2027 |
op_container_end_page |
2041 |
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1766303268100636672 |