Is There Less Sea Ice in the Arctic Than There Used to Be?

Is there less sea ice in the Arctic than there used to be?

Background: The National Snow and Ice Data Center (NSIDC) coordinates data on Arctic Sea ice, which is frozen ocean water. Even though you may never see sea ice, it is very important for global processes. Because it is light in color (unlike liquid ocean water, which looks dark), it reflects the sun’s rays (it has a high albedo) and helps to stabilize global temperature. The graph below shows the most recent update of this year’s sea ice extent in the Arctic. Sea ice extent is the area of ocean covered by sea ice.

This year’s data are compared to data from last year and the long-term average extent. The map shows the most recent extent (in white) and the long-term average extent in the orange outline. (More on sea ice: http://nsidc.org/cryosphere/seaice/)

Data source: National Snow and Ice Data Center (NSIDC) http://nsidc.org/arcticseaicenews/

1. Describe what the graph shows about how sea ice extent in 2013 compares to last year, and to long-term conditions.

[Purpose here is to elicit description of what the graph shows. Sample response:.The graph shows how sea ice extent changes over the course of the year, and it has the lowest values in late summer (September)]

2. I interpret the graph to mean…. [Purpose here is to elicit an explanation (e.g. of the pattern or variability) or interpretation of the meaning in terms of the context of the question. Sample response: In 2013 so far, there has been less extent of sea ice than the long-term average (1981-2010), but there was more than in 2012. For more sophisticated students, you might note that because the 2013 line falls within the gray area (which shows variability in the long term dataset), it seems to be within the normal range, whereas 2012 was way outside that normal range.]