By Andrea Thompson
Feb. 13, 2017
Arctic temperatures have finally started to cool off after yet another winter heat wave stunted sea ice growth over the weekend. The repeated bouts of warm weather this season have stunned even seasoned polar researchers, and could push the Arctic to a record low winter peak for the third year in a row.
Meanwhile, Antarctic sea ice set an all-time record low on Monday in a dramatic reversal from the record highs of recent years.
Sea ice at both poles has been expected to decline as the planet heats up from the buildup of greenhouse gases in the atmosphere. That trend is clear in the Arctic, where summer sea ice now covers half the area it did in the early 1970s. Sea ice levels in Antarctica are much more variable, though, and scientists are still unraveling the processes that affect it from year to year.
The large decline in Arctic sea ice allows the polar ocean to absorb more of the sun’s incoming rays, exacerbating warming in the region. The loss of sea ice also means more of the Arctic coast is battered by storm waves, increasing erosion and driving some native communities to move. The opening of the Arctic has also led to more shipping and commercial activity in an already fragile region.
Sea ice area isn’t the only way to measure the health of Arctic sea ice; the thickness of the sea ice has also suffered during the repeated incursions of warmth.
Thin ice is more susceptible to melt come spring and summer, though it doesn’t guarantee that summer will also see record lows. For example, despite record low levels of sea ice last summer, cool, cloudy weather kept melt somewhat in check. The season still finished with the second lowest summer minimum on record, though.
Antarctic sea ice is an altogether different beast. Instead of an ice-filled ocean surrounded by land, it is a continent surrounded by ocean that sees much more variability in sea ice levels from year to year for reasons that aren’t fully understood.
For several of the past few years, the sea ice that fringed Antarctic reached record highs. That growth of sea ice could have potentially been caused by the influx of freshwater as glaciers on land melted, or from changes in the winds that whip around the continent (changes that could be linked to warming or the loss of ozone high in the atmosphere).
But this year, a big spring meltdown in October and November suddenly reversed that trend and has led to continued record low sea ice levels as the summer melt season progressed. On Monday, Antarctic sea ice dropped to an all-time record low, beating out 1997.