Global climate change has been a pretty hot topic in the world of meteorology and climatology for quite some time now. Skeptics and pro AGW (Anthropogenic — meaning human as opposed to natural — Global Warming) have raged on and on. One of the main components that people like to look at to track the degree of warming is the amount of Arctic Sea Ice loss. As the calendar slides through August and into September, we get closer and closer to the minimum ice extent for the year, before recovering for the fall and winter. Arctic Sea Ice has really declined in the past several years — potentially due to AGW, as the amount of loss last year was absolutely staggering. In fact, the entire 2007-2012 period saw unprecedentedly low levels of Arctic Sea Ice that led many to become quite worried about this being the new normal.
Most global climate simulations indicate that the area of greatest warming would be in the Arctic — mainly because it is easier to heat something that is cold than what is hot. Decreasing the amount of Arctic Sea Ice could lead to lots of devastating climate feedbacks on the Earth’s system, such as a lot less radiation being deflected back into space, and further yielding warming. This is because ice and snow have a higher albedo (ability to reflect heat radiation back into space) than water. Thus, a warming arctic –> more water and less ice & snow –> lower albedo in the arctic –> less heat radiation is reflected back into space (and is instead absorbed by the water) –> warming arctic. This means that the feedback helps to amplify the original effect of warming the arctic, without increasing the warming effect itself.
When the Artic regions are quite warm, this is obviously bad for many ecosystems alike. But it would also greatly alter the weather patterns in that it would change the jet stream configuration, since if you are warming the Arctic a lot more than the equatorial latitudes, you are decreasing the temperature gradient between the two, which is what fuels the jet stream to begin with. There are a lot more climate feedbacks and such, but to save time, we won’t get into that for now.
Figure 1: Arctic Sea Ice extent from this year (red) is much higher than from last year (black). However, it is still well below the 1979-2006 averages.
Arctic Sea Ice can be measured in two ways: ice extent and ice area. The National Snow and Ice Data Center explains the differences well here, but essentially, the analogy is swiss cheese. Extent would be the distance from the edges of the cheese and all of the space inside the edges — so it does not include the holes, whereas the area takes the holes into account. There are pros and cons to using each method, but the NSIDC uses extent.
The chart above shows the Arctic Sea Ice extent from the past several years, in comparison with the 1979-2006 averages. Obviously, we are still well below the 1979-2006 averages, so it is not time to “cancel” global warming. However, we have had a very significant recovery from this time last year — it is almost two million square kilometers above last year’s level! This is great news. Although we are really only near the 2009 level and not necessarily that deviant from the past several years, the increase is quite significant and a bit unprecedented, since year-to-year increases of this magnitude are rare.
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