Arctic sea ice reached its annual maximum extent on March 17, according to analysis by NASA and the National Snow and Ice Data Center. The 2018 extent reached 5.59 million square miles, only about 23,000 square miles larger than the lowest maximum on record, in 2017.
This continues a trend of shrinking sea ice, with the four lowest Arctic sea ice maximum extents on record in the last four years.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 184.108.40.206.0