Thursday, February 19, 2015

The Arctic — Global Warming Is Happening Now

(The top map shows surface temperatures, such as the cold purple areas in the Arctic and far north. The bottom map show temperature anomalies, such as the above average temperatures in Alaska and the abnormally low temperatures in Eastern Canada.)

This is the cold, dark part of the year and close to the time when the Arctic ice reaches its maximum size for the next twelve months. By middle to late March, the Arctic will definitely be shrinking as it always does around that time.

For years now, the Arctic has been shrinking. Records going back over a hundred years makes it clear that the Arctic has been in a long period of declining size, in both area and volume. The National Snow & Ice Data Center has been keeping quality satellite records and posts the numbers daily for area, going back to 1979.

Most people who understand global warming know that it's measured by decades rather by years. There are a number of smaller cycles and year to year variations that mean the measures we see are rarely in a straight line. That is to say, there are variations.

One way to see the variations is to go to the interactive visual called the "Charctic Interactive Sea Ice Graph." The easy to use graph allows you to see the variations by year since 1979. If you use the chart, and start back in 1979 and go one year at at time, you can see how the melting and the freezing of the Arctic varies year by year. And you can easily see that on average, decade by decade, the Arctic in the late summer is getting smaller and smaller. And you can also notice that year by year, the Arctic in late winter, when it reaches its largest extent, is slowly, on average, reaching a smaller and smaller maximum.

Right now, in the last few days, the Arctic is very close to the four smallest maximums on record. Only 2014, 2011, 2006 and 2005 have been as small or smaller. No one knows for sure what will happen in the next three weeks. Right now, the Arctic is still growing but losing ground day by day compared to other years. If the trend continues, always a big if, the lowest maximum record will be set.

In the meantime, the cold air of the Arctic continues to spill out of the Arctic and large patches of warmer than normal surface temperatures are being recorded. The dynamics are not well understood. In the last few years, Alaska and sometimes the Yukon have frequently experienced much higher than normal temperatures in the winter. And eastern Canada and the Eastern United States have been experiencing unusual winter time lows. Somewhat unpredictably, the Arctic at times has patches of higher than normal temperatures that sometime rise as high as 30 degrees Fahrenheit above normal.

 It's not clear yet whether new seasonal patterns in the far north are developing. Probably not. For one thing, Siberia also has cold air that spills out of the Arctic but the cold air spills out in a wider range of locations. Another issue is that the jet stream in the winter is far more erratic and variable than it was ten to twenty years ago. For now, scientists are studying the changes and it will probably take time to understand. But one thing is not changing: the temperatures are rising, more energy is pouring into the systems of the Earth, and many changes are taking place.


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