If it seems like we’ve been here before, then that’s because unfortunately we have. As climate records continue to be smashed in horrifying regularity, this week saw yet another added to the list. The total extent of Arctic sea ice this winter reached its peak at 14.52 million square kilometers (5.607 million square miles), which is the lowest it has ever been during winter since satellite records began in 1979, just beating the previous record low set only last year.
Depressingly, this news is not actually that surprising. It’s been predicted that this will likely be the case since early on in the year, as global average temperature records have continued to tumble. February clocked in as the hottest on record – the third month in a row to do so – and by an unprecedented amount. And as the world warms, the Arctic faces the brunt of the heat as it warms twice as fast as the rest of the planet. “I’ve never seen such a warm, crazy winter in the Arctic,” said the director of the National Snow & Ice Data Center (NSIDC), Mark Serreze. “The heat was relentless.”
This relentless heat has meant that sea ice has not been forming as it should, with the extent below average across the entire Arctic, apart from the Labrador Sea, Baffin Bay, and Hudson Bay. The reasons are twofold, partly due to air temperatures over the Arctic Ocean between December and February being 2 to 6°C (4 to 11°F) above average in almost every region, but also due to warming ocean temperatures, which can have even more dramatic impacts on sea ice growth.
The Arctic sea ice freeze cycle from the last summertime minimum extent to March 24, when it reached its wintertime maximum extent: the lowest maximum extent in the satellite record. NASA Goddard's Scientific Visualization Studio/C. Starr
“It is likely that we're going to keep seeing smaller wintertime maximums in the future because in addition to a warmer atmosphere, the ocean has also warmed up,” explained Walt Meier, a sea ice scientist from NASA’s Goddard Space Flight Center, and member of the NSIDA analysis team. “That warmer ocean will not let the ice edge expand as far south as it used to. Although the maximum reach of the sea ice can vary a lot each year depending on winter weather conditions, we’re seeing a significant downward trend, and that’s ultimately related to the warming atmosphere and oceans.”
How this will translate to summer sea ice extent is not 100 percent clear, as that depends on the onset of the melting, in addition to other atmospheric conditions. Typically, ice extent will be at its total lowest in September, with 2012 so far holding the record minimum sea ice cover. Yet some are already predicting that this trend of continually shrinking sea ice is now “locked in” and inevitably will get smaller and smaller, potentially leading to entirely ice free Arctic summers within 20 to 30 years. How this will affect the wildlife and indigenous communities who depend on the sea ice is yet to be seen.