Dates for the upcoming Arctic GEOTRACES expedition (August–October) were selected to capture the annual period of minimum ice coverage in the Arctic Ocean. During fall and winter, the northern hemisphere tilts away from the sun and ice freezes over the Arctic Ocean reaching maximum coverage by March. In the spring and summer, the northern hemisphere tilts towards the sun and ice begins to melt reaching minimum coverage by September. The U.S. Arctic GEOTRACES team will attempt to reach the geographical North Pole during the ice minimum this September before turning back towards the Bering Strait as temperatures drop and the ice thickens.
Annual ice coverage in the Arctic Ocean is difficult to predict as sea ice extent can be affected by both local weather patterns and global climate change. Overall, Arctic sea ice appears to be declining. Satellite observations are used to determine the extent of ice coverage each year and below average measurements have been recorded since 2003.
Maximum ice coverage in the Arctic Ocean was measured this year on Feb. 25, two weeks ahead of schedule, and is the lowest ice-maximum measured since satellite records began nearly 40 years ago.
Those of you still recovering from this year’s brutal winter of record high snowfall and record low temperatures may find this unbelievable. However, the weak jet stream that caused the polar vortex has an oscillating pattern – while the east coast was inhaling a breath of cold Arctic air, warmth from the equator was pulled up in the western part of the continent. Warmer temperatures in the North Pacific may have decreased ice coverage in the Arctic this year, and together with an already decreasing trend partially attributed to a warming climate, a new low has been reached.
Record low ice coverage this winter does not necessarily guarantee a clear path for the GEOTRACES team to break through to the North Pole. The Arctic Ocean contains a mixture of thick multi-year ice that has been around for at least 5 years, and first-year ice that thaws and re-freezes annually. Record low ice coverage this year means there is less first-year ice than normal, but the thick multi-year ice may stand in our way.