Visualizations : Bubble Chart: Change in Sea Ice Extent, 1979-2004

In the polar region, much of the sea is covered by ice. The amount of water that is covered is called the extent. Because the ice is melting, the extent is decreasing in the Northern Hemisphere.

However, the Southern Hemisphere appears to be experiencing a slight increase. (Toggle Color between Hemisphere and No Selection to see colors according to North/South or Increase/Decrease.) According to the data source, “The IPCC20 concluded
that this overall increase was not significant and
that there are no consistent trends during the period of
satellite observations.” Researchers do not really know why this difference exists, and figuring it out appears to be a high priority. “Researchers are examining
changes in the atmospheric circulation of the two
polar regions as well as changes in ocean circulation.”

The Treemap visualization attached to this same data is also quite useful.

Click on this thumbnail to see a pretty dramatic view of the situation.

Monica, thanks for creating this visualization! Can you tell us a bit more about why there is such a big difference between the Northern and Southern hemispheres?

Updated :-)

The Indian Ocean has sea ice? I guess it extends farther south than I would have thought.

This picture shows it extending all the way down to Antarctica.

:-)

Thanks, Monica! I guess the coastline of Antarctica must hit a bunch of different oceans.

This is cool. I’m no scientist, but wouldn’t it make sense to use the area (or volume) of the sea as a variable (instead of a simple count)? If some dinkly little sea is increasing or decreasing it throws off the visualization, right? The question we all have is what is the overall volume impact? Thanks!