The Human Impacts Database

A collection of useful numbers for quantifying the impacts of the human presence on Earth.

Northern Hemisphere sea ice extent

WaterCryosphere

This quantity comes from a time series measurement and the most recent value (1979-2021) is reported.

Value:

This is equivalent to...

1.0549 × 1013 m2

1.4645 × 107 km2 at yearly maximum cover (March)

1.4645 × 1013 m2 at yearly maximum cover (March)

4.915 × 106 km2 at yearly minimum cover (September)

4.915 × 1012 m2 at yearly minimum cover (September)
HuID: 70188
Relevant Year(s): 1979-2021
Summary: This entry represents the average Northern Hemisphere sea ice extent in each year from 1979-2021. The entry gives three values, each representative of the most recent year: 1) The average yearly sea ice extent, 2) the average sea ice extent in the month of maximum average extent over the period 1979-2021 (March), and 3) the average sea ice extent in the month of minimum average extent over the period 1979-2021 (September).
Method: The Sea Ice Index provides satellite data for sea ice cover described as sea ice extent (calculated by taking the integral sum of the areas within grid cells with > 15% ice concentration) and area (calculated by multiplying the percentage of sea ice in each grid cell with > 15% ice concentration by the area of the grid cell and taking the integral sum of these products) in the northern and southern hemispheres from 1979-2021. No uncertainty is given.
Source: Fetterer, F., K. Knowles, W. N. Meier, M. Savoie, and A. K. Windnagel. 2017, updated daily. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: https://doi.org/10.7265/N5K072F8. [2022-Feb-16]. Sea_Ice_Index_Monthly_Data_by_Year_G02135_v3.0.xlsx. (2017)
Dataset: This file gives the average Northern Hemisphere sea ice extent for each month and year from 1979-2019. (northern_hemisphere_extent.csv)
regional resolution
Trend:
Original Data License: NSIDC Open Data Policy
Added By: nsarai