Sea ice acts as an air conditioner for the planet, reflecting energy from the Sun. On September 17, the Arctic Sea ice reached its minimum extent for 2014 — at 1.94 million square miles (5.02 million square kilometers), it’s the sixth lowest extent of the satellite record. With warmer temperatures and thinner, less resilient ice, the Arctic sea ice is on a downward trend. The red line in the still image indicates the average ice extent over the 30 year period between 1981 and 2011.
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 220.127.116.11.0