Since 1978, scientists have been keeping track of Arctic ice as it advances and retreats each season, but the overall trend is retreat.
Using satellite imaging to measure the age, extent, and thickness of Arctic ice, the National Snow and Ice Data Center (NSIDC) has noted a steady decline over the last few decades, about 12% every ten years. For the last ten years or so, Arctic ice limits have all been in the ten lowest since recording began 36 years ago. The lowest ever recorded was 5.65 million square miles (14.63 million square kilometers), just three years ago, in 2011. This year, March 21, 2014, Arctic ice hit its peak extent, just 5.76 million square miles (14.91 million square kilometers), the fifth-lowest ever measured.
Another worrying trend that the NSIDC has noted is the age of the ice. As the Arctic ice minimum gets smaller every year, there is more young ice than in previous years. For 2013, about 43% of the ice was more than a year old, most of that only two years old. Just 7% of Arctic ice in 2013 was more than five years old, only half the amount of five-year old ice in February, 2007.
Of course, Arctic ice limits have a direct bearing on sea level rise, which is presenting problems for low-lying communities. Even typical tropical storms bring with them even high storm surges, such as occurred in New York City when Hurricane Sandy blew ashore, bringing 100-year flood conditions to the area. Some scientists predict that the Arctic ice minimum may actually be zero as climate change continues to interfere with global temperatures.