NSIDC updating sea ice baseline

[OnlinePoker]

"This July, NSIDC plans to change the baseline climatological period for Arctic Sea Ice News and Analysis and the Sea Ice Index, the data set we use for our sea ice analysis. We are making this change to match the comparison time frames used by other climate research.

Until now, we have used the 22-year period 1979 to 2000 when comparing current sea ice extent to past conditions. When NSIDC first began to monitor and analyze sea ice extent, a longer period was not available. Since the satellite record is now extended, we are choosing to move to a more standard 30-year reference period, from 1981 to 2010..."

http://nsidc.org/arcticseaicenews/

Basically, with the drops in the last 5 years, we will be closer to average each year. Currently, before the change, sea ice extent is still within 2 standard deviations of normal. After the change, that would probably be within 1 standard deviation.

[OnlinePoker]

1. As predicted

So NSIDC has reset their numbers and we are now well within 2 standard deviations of "average" for sea ice extent (but plunging quickly). Sea Ice was 11th lowest extent for June in the satellite record, but the highest since 2004. From the monthly report:

"June is a transition period for Arctic sea ice as 24-hour daylight reigns, and melt reaches towards the North Pole. Thus it is an appropriate time for NSIDC to transition to a new 30-year baseline period, also called a “climate normal.” The satellite record is now long enough to allow NSIDC to match current National Ocean and Atmospheric Administration (NOAA) and World Meteorological Organization (WMO) standard baselines of 1981 to 2010 for weather and climate data. Full details of the changes and the implications for NSIDC sea ice statistics are described in the NSIDC Sea Ice Index.

Average sea ice extent for June 2013 was 11.58 million square kilometers (4.47 million square miles). This was 310,000 square kilometers (120,000 square miles) below the 1981 to 2010 average (the new baseline period) of 11.89 million square kilometers (4.59 million square miles). In comparison, the 1979 to 2000 period that we previously used averaged 12.16 million square kilometers (4.70 million square miles). June 2013 was 760,000 square kilometers (293,000 square miles) above the record low June extent in 2010..."

http://nsidc.org/arcticseaicenews/