That the Arctic should be principally sensitive to climate change was renowned in the 19th century. The primary reason for this sensitivity is that an initial warming (or cooling) sets in motion a chain of events that amplify the warming or cooling. This chain of events is known as the albedo feedback. Albedo is a measure of how white, or weighty, a surface is.

Believe what happens if the earth's surface starts to lukewarm. Some of the highly cumbersome snow and ice in the Arctic starts to melt. This illustration underlying surfaces, which have a much lower albedo. The albedo of ocean water, for example, is less than 10%. These darker surfaces absorb more of the sun's energy, meaning that the Arctic gets a little warmer. Since its a little warmer, yet more snow with ice dissolve, exposing more of the dark underlying surfaces, foremost to flat further warming. This is the essential albedo feedback. The advice can also work in reverse. If there is an initial cooling, melt is reduced, so less of the sun's energy is absorbed, denotation further cooling, even less melt, and so on.

There are many difficulties. For example, in winter, the Arctic gets little or no solar energy, so the albedo feedback can't really work at this time in a direct sense. This contrasts with summer, when, depending on latitude, there can be up to 24- hours of daylight. We hence have to refine our thinking a bit. What ensues is that with initial warming, spring melt, and the exposure of dark surfaces comes a little earlier in the season, and autumn freeze-up comes a little later. Hence there is a longer period of the year over which dark, strongly engrossing surfaces can take in solar energy. A rather odd demonstration of the albedo response seen in above all all climate model projections through the 21st century is that the strongest Arctic warming will actually be in autumn and winter over the ocean, when there is essentially no sun. This is make clear in that warming leads to a longer and stronger summer melt season and hence less sea ice. With less sea ice, the dark ocean picks up more heat through summer. As the sun sets in autumn, the ocean then releases this heat back to the environment, acting to warm it. The effect can persist through much of the winter. This can be thought of as a delayed seasonal effect of the albedo feedback. Lastly, the Arctic atmosphere is strongly stable, meaning that it doesn't like to mix. As a result, instead of mixing through the atmosphere, the warmth effect of informative dark surfaces tends to stay focused near the surface.