Transcripts of Arctic_sea_ice_max_2013_youtube_hq

After a long winter's freeze, the sea ice covering the Arctic Ocean has reached its maximum extent and is showing signs of its annual spring melt. This maximum wasn't as big as it could have been though – it turned out to be the fifth smallest winter peak in 35 years of satellite measurements. Every year, scientists pay close attention to changes in Arctic sea ice. In winter, the frozen ocean surface expands rapidly to cover everywhere from the Hudson Bay to Russia to the northwest coast of Alaska. In the summer, the ice melts back dramatically, exposing more dark ocean water to the rays of the sun. But those summer minimum extents have also generally been getting smaller. In September of 2012, Arctic sea ice shrank to its lowest extent ever measured in the satellite era. While a thinning ice cap and warm temperatures were likely responsible for most of that melt, a strong Arctic cyclone in August also helped break up ice north of the Bering Strait. A large chunk of sea ice broke off from the ice pack and was transported south to warmer waters, where it melted. A thin ice cap also may have contributed to a recent fracturing event north of Alaska this winter. The scale of this phenomenon is almost hard to imagine -- cracks in the ice hundreds of miles long. Sea ice far from shore is always at the mercy of ocean currents and winds, so fractures in the ice are a regular event, but the impressive scale of the cracks here may be due to the prevalence of younger, thinner ice that we've seen in recent years.This year's smaller winter maximum sea ice extent continues a trend of modest decreases in winter maximums. Since the size of the sea ice cap each season is dependent on many factors, like temperatures, winds, and ocean currents, it doesn't necessarily mean that a this year's smaller maximum sets the stage for another record minimum this summer. But researchers say the thinning of the ice does make the ice cap more vulnerable to melting events in the future, to the point where we might see virtually ice-free summers in the Arctic Ocean in just a few decades. 

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