icon of sea ice extent

Description of Sea Ice Extent:

Unlike icebergs, glaciers, ice sheets, and ice shelves, which originate on land, sea ice forms, expands, and melts in the ocean. Sea ice influences global climate by reflecting sunlight back into space. Because this solar energy is not absorbed into the ocean, temperatures nearer the poles remain cool. When sea ice melts, the surface area reflecting sunlight decreases, allowing more solar energy to be absorbed by the ocean, causing temperatures to rise. This creates a positive feedback loop. Warmer water temperatures delay ice growth in the autumn and winter, and the ice melts faster the following spring, exposing dark ocean waters for longer periods the following summer. Sea ice also affects the movement of ocean waters. When sea ice forms, ocean salts are left behind. As the seawater gets saltier, its density increases, and it sinks. Surface water is pulled in to replace the sinking water, which in turn becomes cold and salty and sinks. This initiates deep-ocean currents driving the global ocean conveyor belt. 

 

Sea ice is an important element of the Arctic system. It provides an important habitat for biological activity, e.g. algae grows on the bottom of sea ice, forming the basis of the Arctic food web, and it plays a critical role in the life cycle of many marine mammals - seals and polar bears. Sea ice also serves a critical role in supporting the culture—and even survival—of Indigenous communities. For example, sea ice can be a critical platform for hunting. We present the annual sea ice extent in millions of Kilometers for the Arctic region.

 

Data Source:

Sea ice data was accessed from the NOAA National Centers for Environmental Information for the northern hemisphere, https://www.ncdc.noaa.gov/snow-and-ice/extent/  ; with the data pulled from here: https://www.ncdc.noaa.gov/snow-and-ice/extent/sea-ice/N/0.csv.  The data are plotted in units of millions of square km.    

Arctic

graph of summer sea ice extent in the Alaska-Arctic region from 1980-2020

Values correspond to millions of square kilometers of sea ice cover

 

Description of time series:

This time series shows the sea ice extent for the Alaska-Arctic region from 1979 to 2021. During the last five years, there has been no notable trend and values are within the 10th and 90th percentiles, albeit near the lower end of the time series.

 

 Description of gauge:

The gauge value of 14 indicates that mean sea ice extent between 2017 and 2021 for sea ice in the Alaska-Arctic region was only higher than 14% of the sea ice extent measurements between 1979 and 2021

 

Indicator and source information:

Sea ice affects the movement of ocean waters. When sea ice forms, ocean salts are left behind. As the seawater gets saltier, its density increases, and it sinks. Surface water is pulled in to replace the sinking water, which in turn becomes cold and salty and sinks. This initiates deep-ocean currents driving the global ocean conveyor belt. 

 

The time series shows the Sea Ice extent in September of each year to give a sense of the summertime (i.e., minimum annual) extent through the years of sea ice across the entire Northern Hemisphere, which includes the Arctic Ocean and the Hudson Bay. 

 

Data background:

Sea ice data was accessed from the NOAA National Climatic Data Center for the northern hemisphere, https://www.ncdc.noaa.gov/snow-and-ice/extent/ ; With the data pulled from here: https://www.ncdc.noaa.gov/snow-and-ice/extent/sea-ice/N/0.csv.  The data are plotted in units of million square km.    

 

Resources

National Snow and Ice Data Center (NSIDC) Sea Ice and Snow Cover Extent

Sea ice extent provided by the National Snow and Ice Data Center (NSIDC) is available from 1979–2020 for the Northern Hemisphere, Southern Hemisphere, and Globe. Snow cover extent provided by the Rutgers University Global Snow Laboratory (GSL) is available from 1967–2020 for the North America + Greenland, Northern Hemisphere, Eurasia, and North America. All anomalies are relative to the 1981–2010 average.

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Alaska IEA Conditions Report (Bering Sea)

Ecosystem Status Reports are produced annually to compile and summarize information about the status of the Alaska marine ecosystems for the North Pacific Fishery Management Council, the scientific community and the public. As of 2016, there are separate reports for the the Eastern Bering Sea (updated 2019), Aleutian Islands (updated 2018), the Gulf of Alaska (updated 2019), and Arctic (forthcoming) ecosystems. These reports include ecosystem report cards, ecosystem assessments, and ecosystem and ecosystem-based management indicators that together provide context for ecosystem-based fisheries management in Alaska.

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NOAA Arctic Report Card

Tracking recent environmental changes relative to historical records

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Climate Change Indicators in the US (4th Edition)

EPA partners with more than 40 data contributors from various government agencies, academic institutions, and other organizations to compile a key set of indicators related to the causes and effects of climate change. The indicators are published in EPA's report, Climate Change Indicators in the United States, available on this website and in print. Explore the indicators below.

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NOAA Arctic Program

NOAA provides science, service, and stewardship to the rapidly changing Arctic region, its inhabitants, and the nation.

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Alaska Region Sea Ice Forecasts

National Weather Service Alaska Sea Ice Program products and tools.

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