2017 has proven itself an exceptional year for both the Arctic and Antarctic, with the amount of ice at both poles reaching the lowest levels in 38-year satellite records. The data was released by NASA and the US National Snow and Ice Data Centre (NSIDC).
The natural temperature fluctuations that come with our planet’s seasons mean the sea ice extent — a measure climate scientists use to catalogue ice coverage — hits highs and lows each year.
The amount of ice at the Arctic usually reaches a maximum in March each year, following the northern hemisphere winter; this year peaking on the seventh of the month.
The trouble is that this maximum is the lowest recorded since these kinds of satellite records began back in 1979.
The other end of the planet hasn’t fared much better either. Around this time each year, the ice extent in the Antarctic dips to a post-summer minimum, but 2017 has seen a record low here too.
Compared to the 1981 – 2010 average, the two poles together have lost an area of sea ice the size of Mexico.
The release comes from US National Snow and Ice Data Centre (NSIDC).
What’s causing it?
Climate scientists say the problem in the Arctic this year is due to localised weather effects combined with higher-than-average temperatures in the region.
Stormy winds throughout the winter months have churned up the seas and led to conditions that aren’t conducive to ice growth, and the region was already facing a low ice extent after a particularly warm summer.
The Arctic mercury has been behaving particularly erratically on the short-term too. During the winter of 2016/17, swathes of the region experienced temperatures nearly 20 degrees Celsius higher than usual, even during the near-sunless polar night.
Though this extreme jump in temperature was short-lived, scientists say such freak-temperature events are made “more likely by orders of magnitude due to climate change,” and can be expected to occur more frequently year-on-year.
To compound the problem, the ice that is present in the Arctic is thinner than usual, according to data taken with the CryoSat-2 satellite. As the top layers of ice melt away, the older ice beneath that has remained frozen in the region for aeons is being exposed, leaving it vulnerable to melting and thinning.
Trends of sea ice in the northern pole have shown an average of 2.8% reduction every decade, and though this year’s record low wintertime extent may not necessarily lead to an equally-record low summer level, it is, according to researchers, “guaranteed to be below normal.”
Action at both ends
The southern tip of our planet is not escaping the clutches of climate change either. Having just come to the end of its summer, ice in the Antarctic is at its normal annual minimum. But this year, the region’s sea ice extent is the lowest minimum recorded since satellites began to survey to continent.
This is especially surprising since, until this year, Antarctic ice had slowly been growing, with the data showing steady annual increases.
Overall trends of sea ice in from 1979 – 2017, measured by satellites. The top line is the Arctic; the middle is Antarctica; and the third shows the combined total. Credits: Joshua Stevens/NASA Earth Observatory
Reasons for this growth aren’t immediately clear, but some scientists propose it could be to do with overall warmer air in the region — as a result of human actions — being able to hold and precipitate greater levels of snowfall.
This year’s sudden dip has therefore come as a surprise to climate scientists, who have described it as “stunningly different” and “definitely of interest.”
It is not clear what the immediate cause of this fall in ice is, and researchers are refusing to draw solid conclusions from a single year’s data. Instead, more measurements taken over a longer period of time are needed to rule out this year being a statistical anomaly.
Our planet’s climate is undergoing a period of extremely quick change, and record results like these are not only understandable, but expected. 2017 has seen extreme ice melting at both tips of the Earth, and while the situation in the Antarctic appears to have bucked a recent cautious upward trend, the Arctic is continuing on its long-established downward spiral.