Essential Question:
How are Arctic sea-ice, climate and culture all connected?
Icy - I See Why
Our planet uses many of the same tricks that over-heated humans use to cool off. Our circulatory system is like the great ocean currents moving our excess heat to cooler places. We mist and fan ourselves, put on a white shirt and white broad-brimmed hat, or we head for the shade.
Likewise, Earth wears a white broad-brimmed polar cap that reflects radiant energy instead of absorbing it. Its raft of floating clouds create shade and its winds carry heat in the form of evaporated water away to cooler places. Same-same.
Along with the hydrosphere and lithosphere and atmosphere, we also have a region of Earth called the cryosphere that is dominated by ice. It's a relatively new term in our common language, but it's understanding is important as we learn more about the separate, but connected variables influencing climate on Earth.
It seems Earth's icy poles provide the very desirable function of disposing excess planetary heat absorbed at lower latitudes. Because, as we learned in previous modules, heat moves from where it's hot, to where it's not.
See Ice - Sea Ice
If you live in Alaska near both fresh water and the ocean, you may have noticed each winter that the lakes freeze before the sea does, if it does at all. So, it won't surprise you to hear it takes a pretty cold climate to absorb enough heat from our salty Arctic ocean to force it to surrender to freezing.
Though fresh water reaches maximum density and begins to freeze at approximately +4 Celsius, salty sea surface temperatures must dip to around -3 Celsius before it can begin to form the hydrogen bonds that make it a solid.
Curiously, even at extremely low temperatures, ice still doesn't associate well with salt. The sea water excludes most of the salt ions as it freezes, forcing them out into the water just below the forming ice.
You probably remember earlier we discussed how such super-cooled, super-saline water has the distinction of also being the densest water in the ocean, and therefore sinks in the polar regions to create deep ocean bottom currents - a process called thermohaline circulation.
Strange though it seems, freezing water also gives off heat. Since salt water freezes at a lower temperature than fresh water, it must, therefore, surrender even more thermal energy than fresh water does to its surrounding environment - the even colder atmosphere.
Taken on a large scale, this flux of thermal energy caused by the phase change from liquid to solid water is just one more important method the Earth uses to move heat from where it's hot to where it's not.
EXPLORE
Teachers Domain
Let's explore some more cool science by chilling-out with some TD resources.
Earth's Cryosphere: The ArcticArctic Climate SystemHow the Arctic Ecosystem Might ChangeEXPLAIN
- How does the Arctic Ocean influence climate elsewhere on the planet?
- Why are the affects of climate change more dramatic in the Arctic than lower latitudes?
- Why is the Arctic ecosystem both highly productive, and at the same time fragile?
- Why is the marine ecosystem more vulnerable to climate changes?
- What kind of snow and ice data exists for your region?
- Are there elders in your area who have a sense of local snow and ice dynamics?
- How are the different positive feedback loops were mentioned in these TD resources connected?
EVALUATE
- What are the values of integrating local Native knowledge with global scientific studies?
