Climate change is not only causing the Arctic sea ice to melt because it heats the atmosphere above it, but also through heat advection, by warming ocean currents that make contact with the ice.

New sediment measurements off the coast of Svalbard find temperatures of Atlantic waters entering the Arctic were constant from the year AD 1 until the 1850s. After that period the average water temperature gradually rose by 2 degrees, the researchers, of Leibniz Institute of Marine Sciences, write in their publication in Science.

This means excess heat is being stored in the deep waters of the Arctic. As warmer waters are lighter some contact with the ice is inevitable – although a layer of cold but fresh melting water can slow the mingling down.

The research highlights that atmospheric protection of the Arctic, however difficult [a recent publication in Nature states the 450 Scenario may lead to a preserved equilibrium state of 2.5 million square kilometers of ice], is not enough to stop melting. Because oceans are not only inert while warming up, they are also extremely slow when you want them to cool down again.

© Rolf Schuttenhelm | www.bitsofscience.org