The sun rises two days early in Greenland, sparking fears that climate change is accelerating

[Ronan Kelly]

The sun rises two days early in Greenland, sparking fears that climate change is accelerating
By Daily Mail Reporter
Last updated at 4:29 PM on 14th January 2011

The sun over Greenland has risen two days early, baffling scientists and sparking fears that Arctic icecaps are melting faster than previously thought.

Experts say the sun should have risen over the Arctic nation's most westerly town, Ilulissat, yesterday, ending a month-and-a-half of winter darkness.

But for the first time in history light began creeping over the horizon at around 1pm on Tuesday - 48 hours ahead of the usual date of 13 January.
The mysterious sunrise has confused scientists, although it is believed the most likely explanation is that it is down to the lower height of melting icecaps allowing the sun's light to penetrate through earlier.

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Read more: http://www.dailymail.co.uk/sciencet...limate-change-accelerating.html#ixzz1BOecnGiK

 

[Ronan Kelly]

Re: The sun rises two days early in Greenland, sparking fears that climate change is accelerating

From The Strait of Magellan Blog;

Global warming blamed for melting the horizon as sun comes up 48 hours too soon in Greenland


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4) It's already been reported that Ilulissat suffered massive deglaciation earlier in 2010.


5) One mile south of Ilulissat (the direction the sun would briefly rise) are rocky hills about 100 meters high, which would constitute the visible horizon. The hills would appear about 2? (or 2 cm by kamal) higher than the mathematical horizon, so in order for the previous year's ice to obscure the sun (at 30' arc diameter) the ice the previous years would have had to have been 25 meters thicker than this year.

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http://straitofmagellan.blogspot.com/2011/01/global-warming-blamed-for-melting.html

From Rob Sparks at National Optical Astronomy Observatory in Tucson, The Half-Astrophysicist Blog;

Greenland?s Early Sunrise

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But how many meters of melting would have to take place? The math is easy, but knowing the numbers to use is difficult. The answer depends very much on how far away these glaciers are located. Looking at Google Earth and Google maps is of limited utility since you I would need to know exactly where they were looking!

However, I can still make some general calculations here. Let?s say the horizon is 10,000meters away (about six miles). The height the glaciers must have lost is simply the angle times the distance to the mountains (using the small angle approximation here and the angle is small enough that works pretty well) or 10,000*.007 = 70 meters or about 220 feet! Of course, if the glacier is much closer, the amount of ice lost could be much smaller. If you were 1000 meters away, it would only need to lose 7 meters (about 22 feet) off the top. However, without information on exactly where the observation was made, there?s not much you can say about it (although that hasn?t stopped any of the whackos out there!)

Now I should also point out that it could also be due to the ground rising. As glaciers melt, the ground will rise as there is less weight on it. I doubt this could rise enough in one year to create the effect by itself, but if the glaciers fell a little and the ground rose you might be in business.

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Much more likely is an atmospheric phenomena. A certain rare but understood shape of ice crystal (called a pyramidilly-terminated hexagonal prism for those following along at home) can produce a halo with a radius of 4 degrees. This halo would extend a little above the horizon giving the illusion of a sunrise. I think it is fairly safe to say that Greenland is cold enough for atmospheric ice crystals to form at this time of year. These are pretty rare but then again this doesn?t happen every year! Again, a good picture of this would be amazingly useful.

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http://halfastro.wordpress.com/2011/01/14/greenlands-early-sunrise/