» The Global Change Master Directory

The Global Change Master Directory is a comprehensive directory of information about Earth science data, including a broad coverage of global warming, the oceans, atmosphere, hydrosphere, solid earth, biosphere and human dimensions of global change. FGDC Clearinghouse Node (NASA).

http://gcmd.nasa.gov/

» OceanPortal

OceanPortal is a high-level directory of Ocean Data and Information related web sites.

http://ioc.unesco.org/oceanportal/browse.php?cat=274

» The Antarctic Master Directory (AMD)

The Antarctic Master Directory (AMD) is a large metadata database maintained by the Global Change Master Directory (GCMD). It contains metadata records from the National Antarctic Data Centres (NADC's) of each of the Antarctic Treaty nations. However this database is currently not updated as often as the independent databases maintained by each of the NADC's.

http://www.aad.gov.au/default.asp?casid=3957