Field Notes: Omega Block I

In the second week of April of 2016, scientists witnessed the earliest melt event in Greenland's recorded history. The event was caused by an atmospheric traffic jam called an “omega block” because the jet stream is contorted enough to resemble the Greek letter image. “Block” is a meteorological term for an anomalous high-pressure system that acts like an atmospheric mountain, causing warmer air to stream north towards the arctic. As a result, southern Greenland experienced summer like temperatures on April 11th, with Kangerlussuaq reaching 64°F (17.8°C). The Danish Meteorological Institute (DMI)’s model for surface melt showed an estimated 12% of the Greenland ice sheet had melted 1mm or more by this day, representing the earliest melt onset under the DMI definition, and 3 weeks earlier than the previous early melt of 2010. The “omega block” phenomena is believed to be caused by feedback loops from global warming. Since 2002, Greenland's ice sheet has lost over 3,000 gigatons of ice mass. These are some of the very first images showing the melt even taken.

NASA Icebridge Mission, May 2016