Global Warming

Sea Ice Hits Record Lows at Both Poles

    

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.

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.

Sea ice has been particularly low in the Amundsen Sea region of Western Antarctica, thanks to unusually high temperatures there. But it’s not clear what is ultimately driving this dramatic reversal in Antarctic sea ice, or whether it will be temporary or marks a longer-term shift.

Humans accelerating global warming by 170 times: study

Humans are driving the warming of the Earth 170 times faster than natural forces, according to a new mathematical formula.

Scientists in Australia and Sweden have developed the equation, which assesses the impact of human activity on the climate and compares it to events such as volcanic eruptions and changes to the planet’s orbit.

Professor Will Steffen, a climate scientist from the Australian National University (ANU), said no natural events came close to the impact humans have made.

“Over the last century or so, we can see that the impact of humans – through fossil fuels, through forest clearing, through all sorts of changes to the biosphere – have become more important than these other forces,” he said.

Professor Steffen, who is also on the Climate Council, and his fellow researchers have labelled the formula the Anthropocene Equation.

Officially, the Earth is in the Holocene period, but scientists such as Professor Steffen are pushing for the modern era to be reclassified to reflect the massive impact humans have had. The scientists behind the formula found the biggest change in the climate has come since 1970.

“Since 1970, temperature has been rising at a rate of about 1.7 degrees per century,” Professor Steffen said.

“When you compare those two, since the 1970s, the climate has been changing at a rate 170 times faster than that long-term background rate.”