Arctic sea ice appears to have reached its yearly summertime minimum extent for 2017, according to scientists at the NASA-supported National Snow and Ice Data Center (NSIDC) in Boulder, Colo. Observations indicate that on September 13th, ice extent shrunk to the eighth lowest minimum extent in the satellite record, at 4.64 million sq km, or 1.79 million sq mi.
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 8.0.0.0.0