It’s finally here! Yesterday, scientists from the National Snow and Ice Data Center announced the ultimate sign of spring: Arctic sea ice reached its winter peak on March 21, 2014, and the annual melt season is underway.

This winter’s maximum sea ice extent in the Arctic was 14.91 million square kilometers (5.76 million square miles), making it the fifth smallest winter maximum since satellite records began in 1979.

Meanwhile, Southern Hemisphere sea ice reached its annual low point on February 23, 2014. This year’s summer minimum extent was 3.54 million square km (1.37 million square mi), which was the fourth largest in the satellite record.

Global warming due to rising atmospheric concentrations of carbon dioxide and other greenhouse gases is having different impacts on sea ice patterns in the Arctic versus the Antarctic. The Arctic is experiencing declines in ice cover in nearly all areas and all seasons, with especially large losses in summer.

In the Antarctic, sea ice trends are more variable. Over the Southern Ocean as a whole, sea ice extent has increased by a small amount on an annual basis, with decreases in some basins and increases in others and changes in some seasons but not others.

For more on differences between our planet’s two “ends of the Earth” see our Polar Opposites feature article.

Globes by Dan Pisut, based on data provided by the National Snow and Ice Data and available from NOAA View.