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With the sun setting and the onset of polar darkness, the Arctic Ocean would normally be encrusted with sea ice along the Siberian coast. But this year the water is still open.
I have witnessed the region’s transformations since the 1980s as an Arctic climate scientist and, since 2008, as the director of the National Snow and Ice Data Center. I can tell you, it’s not normal. There is so much more heat in the ocean now than there was that the fall ice growth pattern has been completely disrupted.
To understand what’s happening to sea ice this year and why it’s a problem, let’s look back to summer and the Arctic Ocean itself.
The summer of 100 degrees in Siberia
The summer melt season in the Arctic began early. A Siberian heatwave in June pushed air temperatures above 100 degrees Fahrenheit in Verkhoyansk, Russia for the first time in history, and unusual heat spread across much of the Arctic for weeks.
The Arctic as a whole last summer was the hottest since at least 1979, when satellite measurements began providing data that allowed for full coverage of the Arctic.
With that heat, large areas of sea ice soon melted, and the melting initiated a feedback process: the loss of reflective sea ice exposed the dark open ocean, which readily absorbs the sun’s heat, promoting even more melting of the sun. ice.
The North Sea route along the Russian coast was essentially free of ice by mid-July. It might be a dream for shipping interests, but it’s bad news for the rest of the planet.
The heat creeps underwater
The hot summer is only part of the explanation for this year’s unusual sea ice levels.
Streams of warmer water from the Atlantic Ocean flow into the Arctic in the Barents Sea. This warmer, saltier water than the Atlantic is usually quite deep under the livelier Arctic water on the surface. Lately, however, the water of the Atlantic has crept in. That warmth in the Atlantic water helps prevent ice from forming and melting existing sea ice from below.
It is a process called “Atlantification”. The ice is now being hit both from above by a warm atmosphere and from the bottom by a warming ocean. It’s a real double whammy.
While we are still trying to catch up with all the processes leading up to Sanctification, it is here and it is likely to get stronger.
The onslaught of climate change on sea ice
Against the background of all this is global climate change.
The extent and thickness of Arctic sea ice has declined for decades as global temperatures rise. This year, when the ice reached its lowest extent in September, it was the second lowest on record, just after that of 2012.
As the Arctic loses ice and the ocean absorbs more solar radiation, global warming is amplified. This can affect ocean circulation, weather patterns, and arctic ecosystems that span the food chain, from phytoplankton to top predators.
On the Atlantic side of the Arctic, the open sea this year extended up to 5 degrees from the North Pole. The new Russian icebreaker Arktika, on its maiden voyage, found it easy to navigate to the North Pole. One of the goals of his trip was to test how the nuclear-powered ship handled thick ice, but instead of the hoped-for 10-foot-thick ice, most of the ice was in a loose pack. It was a little over 1 meter thick, offering little resistance.
In order for sea ice to build up again this year, the upper layer of the Arctic Ocean must lose the excess heat collected over the summer.
The pattern of regional anomalies in ice extent differs each year, reflecting influences such as regional patterns of temperature and winds. But today, it has overlapped with general ice thinning as global temperatures rise. If the same atmospheric patterns underlying this year’s great ice loss off Siberia had occurred 30 years ago, the impact would have been much less, as the ice was more resilient then and could have taken a punch. Now he can’t.
Is sea ice headed for a tipping point?
The decay of Arctic sea ice cover shows no signs of stopping. However, there probably won’t be a clear tipping point for sea ice.
Research so far suggests that we will stay on the current path, with the amount of ice declining and the weather systems breaking ice more easily because it is thinner and weaker than it was in the past.
The bigger picture
This year’s events in the Arctic are only part of the 2020 climate change story.
Global average temperatures have been at or near record highs since January. The West has been both hot and dry – the perfect recipe for massive wildfires – and hot water in the Gulf of Mexico has helped fuel more tropical storms in the Atlantic than there are letters in the alphabet. If you’ve ignored climate change and hoped it will vanish, now would be a good time to pay attention.
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