This week Q&A is about sea ice.

Why is sea ice loss in the Poles so scary for the planet?

Let us know what you think in the comments session below or on our other online plateforms (Facebook, Instagram, Twitter…). We will publish the answer at the end of this week.

Antarctic_Ice_Valentina

Drift ice along the coast of Antarctica. Picture by Valentina Savaglia

ANSWER:

Sea ice from Polar Regions is melting at a very high rate. Since it is composed by sea water, sea ice melting does not directly raise sea level. Therefore, why is that so worrying? Because of its brightness, sea ice reflects sun’s heat towards the space (high albedo). However, with sea ice loss, instead of being reflected, more heat is absorbed from the dark ocean waters (with a low albedo), accelerating warming of the polar region.

Albedo
Schematic explanation of the Albedo effect.

But where this warmer and less salty sea water is supposed to go? The Poles are the place where the so called ‘new waters’ form. Waters from these places of Earth are normally very cold and dense and thus able to sink very deep in the ocean at the edge of the ice. They actually work as the engine of the major ocean currents (thermohaline circulation). High amount of sea ice melting frees low saline water (= low  density) that does not dive into the deep and thus slows this global “conveyor belt”. Among others, this effect weakens the Gulf Stream which is responsible of the mild European winters.

Many more effects that melting sea ice bring with itself, and we are going to speak more about this on another post… Stay tuned for our summer Q&A posts!

Want to know more?

https://www.nature.com/articles/s41467-019-09237-3

https://phys.org/news/2019-03-ocean-conveyor-belt-foretold-abrupt.html

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007GL031480

 

Written by Valentina Savaglia & Jens Rassmann.