--- attributes: ~ caption: 'The length of the season in which differences in lake temperatures with depth cause stratification (separate density layers) is increasing in many lakes. In this case, measurements show stratification has been increasing in Lake Tahoe (top left) since the 1960s and in Lake Superior (top right) since the early 1900s in response to increasing air and surface water temperatures (see also Ch. 18: Midwest). In Lake Tahoe, because of its large size (relative to inflow) and resulting long water-residence times, other influences on stratification have been largely overwhelmed, and warming air and water temperatures have caused progressive declines in near-surface density, leading to longer stratification seasons (by an average of 20 days), decreasing the opportunities for deep lake mixing, reducing oxygen levels, and causing impacts to many species and numerous aspects of aquatic ecosytems.0bd9cfef-4cd5-4b20-b953-04ecad0bd71c Similar effects are observed in Lake Superior,5d9dedb4-4383-471f-9cee-05e0b16a457c where the stratification season is lengthening (top right) and annual ice-covered area is declining (bottom); both observed changes are consistent with increasing air and water temperatures.' chapter: description: ~ display_name: 'Chapter 3: Water Resources' doi: 10.7930/J0G44N6T identifier: water-resources number: 3 report_identifier: nca3 sort_key: 30 title: Water Resources url: http://nca2014.globalchange.gov/report/sectors/water chapter_identifier: water-resources cited_by: [] contributors: [] create_dt: 2013-08-28T16:38:00 description: 'The length of the season in which differences in lake temperatures with depth cause stratification (separate density layers) is increasing in many lakes. In this case, measurements show stratification has been increasing in Lake Tahoe (top left) since the 1960s and in Lake Superior (top right) since the early 1900s in response to increasing air and surface water temperatures (see also Ch. 18: Midwest). In Lake Tahoe, because of its large size (relative to inflow) and resulting long water-residence times, other influences on stratification have been largely overwhelmed, and warming air and water temperatures have caused progressive declines in near-surface density, leading to longer stratification seasons (by an average of 20 days), decreasing the opportunities for deep lake mixing, reducing oxygen levels, and causing impacts to many species and numerous aspects of aquatic ecosytems.0bd9cfef-4cd5-4b20-b953-04ecad0bd71c Similar effects are observed in Lake Superior,5d9dedb4-4383-471f-9cee-05e0b16a457c where the stratification season is lengthening (top right) and annual ice-covered area is declining (bottom); both observed changes are consistent with increasing air and water temperatures.' display_name: '3.7: Observed Changes in Lake Stratification and Ice Covered Area' files: - display_name: Water_lake_stratification_V5.png file: 49/d1/31c8428b01dcea2a9f24aaef3681/Water_lake_stratification_V5.png href: http://data.globalchange.gov/assets/49/d1/31c8428b01dcea2a9f24aaef3681/Water_lake_stratification_V5.png identifier: 37a53cfb-4a9d-48a5-9eec-85386905d4f2 landing_page: ~ location: ~ mime_type: image/png sha1: 9390760eba1cdaa0f89e6daf09b01e53201feee4 size: 243049 thumbnail: 49/d1/31c8428b01dcea2a9f24aaef3681/.thumb-37a53cfb-4a9d-48a5-9eec-85386905d4f2.png thumbnail_href: http://data.globalchange.gov/assets/49/d1/31c8428b01dcea2a9f24aaef3681/.thumb-37a53cfb-4a9d-48a5-9eec-85386905d4f2.png type: file uri: /file/37a53cfb-4a9d-48a5-9eec-85386905d4f2 url: http://data.globalchange.gov/assets/49/d1/31c8428b01dcea2a9f24aaef3681/Water_lake_stratification_V5.png href: http://52.38.26.42:8080/report/nca3/chapter/water-resources/figure/observed-changes-in-lake-stratification-and-ice-covered-area.yaml identifier: observed-changes-in-lake-stratification-and-ice-covered-area images: - attributes: ~ create_dt: 2013-08-28T16:38:00 description: ~ identifier: 2b483d0b-dc48-4007-943a-2bd38d5aaa76 lat_max: ~ lat_min: ~ lon_max: ~ lon_min: ~ position: ~ submission_dt: ~ time_end: ~ time_start: ~ title: 'Observed Changes in Lake Stratification and Ice Covered Area - Lake Tahoe: Stratification Season Length (Top Left)' url: ~ usage_limits: ~ - attributes: ~ create_dt: 2013-08-28T16:38:00 description: ~ identifier: 43ad9e77-0e20-461a-9e1c-9959d3b7c407 lat_max: ~ lat_min: ~ lon_max: ~ lon_min: ~ position: ~ submission_dt: ~ time_end: ~ time_start: ~ title: 'Observed Changes in Lake Stratification Season and Ice Covered Area - Lake Superior: Stratification Season Length (Top Right)' url: ~ usage_limits: ~ - attributes: ~ create_dt: 2013-08-28T16:38:00 description: ~ identifier: 83f975af-ad98-4911-b540-9c2d3f49293e lat_max: ~ lat_min: ~ lon_max: ~ lon_min: ~ position: ~ submission_dt: ~ time_end: ~ time_start: ~ title: 'Observed Changes in Lake Stratification Season and Ice Covered Area - Lake Superior: Ice Covered Area (Bottom)' url: ~ usage_limits: ~ kindred_figures: [] lat_max: ~ lat_min: ~ lon_max: ~ lon_min: ~ ordinal: 7 parents: [] references: - href: http://52.38.26.42:8080/reference/0bd9cfef-4cd5-4b20-b953-04ecad0bd71c.yaml uri: /reference/0bd9cfef-4cd5-4b20-b953-04ecad0bd71c - href: http://52.38.26.42:8080/reference/5d9dedb4-4383-471f-9cee-05e0b16a457c.yaml uri: /reference/5d9dedb4-4383-471f-9cee-05e0b16a457c report: display_name: 'Climate Change Impacts in the United States: The Third National Climate Assessment' report_identifier: nca3 source_citation: ~ submission_dt: ~ time_end: ~ time_start: ~ title: Observed Changes in Lake Stratification and Ice Covered Area type: figure uri: /report/nca3/chapter/water-resources/figure/observed-changes-in-lake-stratification-and-ice-covered-area url: http://nca2014.globalchange.gov/report/sectors/water/graphics/observed-changes-lake-stratification-and-ice-covered-area usage_limits: Copyright protected. 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