So far this month NSIDC have suspended all processing of the Sea Ice Index (G02135). This is explained on the NSIDC Sea Ice Index page as follows.
Notice (04/05/2016): Due to issues with the DMSP-F17 SSMIS data used to create the Sea Ice Index, we are suspending processing and investigating the problem with our data providers. Learn More. For questions, contact NSIDC User Services.