Artic Warming

Subject: Environment

Context:

The Arctic Circle has recorded likely all-time high temperatures reaching over 38 degrees Celsius in the Siberian town of Verkhoyansk which seem to have been 18 degree Celsius higher than normal in June.

Concept:

• The Arctic’s extreme warming, known as Arctic amplification or polar amplification, may be due to three factors.
• One, the region’s reflectivity, or albedo is changing as the world warms.
• If the sea ice melts in the Arctic that will remove that white surface off of the ocean, and what will be exposed is this darker ocean surface that will absorb more of the sun’s heat.
• This dovetails with the second factor: changing currents.
• Ocean currents normally bring in warmer water from the Pacific, and colder water exits out of the Arctic into the Atlantic.
• But those currents may be changing because more melting ice is injecting the Arctic Ocean with freshwater, which is less dense than saltwater, and therefore floats above it.
• The missing ice also exposes the surface waters to more wind, speeding up the Beaufort Gyre in the Arctic, which traps the water it would normally expel into the Atlantic.
• This acceleration mixes up colder freshwater at the surface and warmer saltwater below, raising surface temperatures and further melting ice.
• Ocean currents influence the weather, a third factor.
• They drive the powerful polar jet stream, which moves hot and cold air masses around the Northern Hemisphere. This is a product of the temperature differences between the Arctic and the tropics.
• But as the Arctic warms, the jet stream now undulates wildly north and south. This has been injecting the Arctic with warm air in the summer and the US with extremely cold air in the winter, like during the “polar vortex” of January 2019.