Several media outlets from Time Magazine to local Alaska papers have confirmed that the 15 mile long organic blob floating in the Chukchi Sea, the waters between Alaska and Siberia, is indeed an algal bloom. But how common are algal blooms so high up in the northern hemisphere? Apparently, if the conditions are right, nutrients, temperatures, currents, etc., they can form. In fact, a quick google search uncovered a paper (pdf) by R. Gradinger from the Institut fur Polarokologie in Germany that describes an algal bloom under arctic pack ice. To get an idea of the magnitude of the Curkchi Sea algal bloom watch the YouTube Video below:
And, for entertainment purposes only, here's the original trailer for the 1958 movie The Blob starring Steve McQueen.