It’s official: with a few weeks of melting left to go, the extent of sea ice remaining in the Arctic this summer has already passed the record low set in 2007.

By both of the most common measures, the extent of Arctic sea ice has reached a minimum never before seen since scientists began measuring it back in the late 1970s. In fact, it’s likely not been seen for centuries, if not millennia.

We hear a lot about “the melting Arctic.” The truth is, the Arctic melts every summer – at least to a certain extent. It’s a regular pattern of freezing for about nine months and melting back for about three. There is always ice remaining at the end of the summer; it doesn’t all melt away – yet.

But on average over at least the last 30 years, there has been a steady decline in both the amount and thickness of the Arctic ice remaining by the end of summer. Within a few weeks, the Arctic will begin to freeze up again, but it will be starting with less ice than it’s had since people have been measuring it.

There is nothing particularly significant about the record itself: on August 26, the Arctic sea ice extent fell below 4.10 million square kilometres. The significance lies in the pattern of decreasing sea ice that it so strongly reaffirms.

The graph above shows Arctic sea ice extent (area of ocean with at least 15 per cent ice) as of August 26, 2012, along with daily ice extent data for 2007, the previous record low year, and 1980, the record high year. Photo Credit National Snow and Ice Data Center.

What happens in any given single season is basically just weather. We start talking about changes in climate only when we see long-term trends. All six of the lowest sea ice extents measured have occurred within the last six years, and we are well below the average measured over the last 30 years.

What does that really mean? That generally depends on who you ask. For wildlife biologists, it means a change in habitats, diets, predator and prey interactions for the animals; for the people who rely on the Arctic environment and the critical cultural, social, economic and nutritional needs for which it provides, it means significant changes to a millennia-old way of life, food security, health and well-being; for those who might benefit from greater access to resources buried in the frozen ground or under the sea ice, it means great economic opportunity.

For governments that once had little interest in the frozen Arctic ocean, it means access to new shipping routes, fishing areas and renewed discussion of political boundaries; and for those of us elsewhere in the world, it means changes in climate and weather patterns, agriculture and infrastructure needs and a lot more.

Over the next few weeks, we’ll try and make sense of both the science and the significance of the decreasing Arctic sea ice. I hope you’ll join us for the conversation.


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