Throughout 2020, the Arctic Ocean and surrounding seas sustained numerous significant weather condition and environment occasions. In spring, a consistent heatwave over Siberia provoked the quick melting of sea ice in the East Siberian and Laptev Seas. By the end of summer season, Arctic Ocean ice cover melted back to the second-lowest minimum extent on record. In autumn, the yearly freeze-up of sea ice got off to a late and sluggish start.
But any single month, season, or even year, is just a picture in time. The long view is more telling, and it is bothering.
Forty years of satellite information reveal that 2020 was simply the latest in a decades-long decrease of Arctic sea ice. In a review of clinical literature, polar researchers Julienne Stroeve and Dirk Notz laid out some of these changes: In addition to shrinking ice cover, melting seasons are getting longer and sea ice is losing its durability.
Balanced across the whole Arctic Ocean, freeze-up is occurring about a week later per years.
Open ocean water soaks up 90 percent of the Sun’s energy that falls on it; intense sea ice shows 80 percent of it. Till that heat leaves to the atmosphere, sea ice can not regrow.
The chart above shows another way the Arctic is changing: the average age of sea ice is becoming more youthful. At the start of the satellite record, much of the ice covering the Arctic Ocean was greater than 4 years old. Today, the majority of the ice covering the Arctic Ocean is “first-year ice”– ice that forms in winter season and does not make it through a single summer melt season. (After sea ice reaches its minimum level each September, the remaining ice graduates to second-year status.)
Controlled by thin first-year ice, together with some older ice thinned by warm ocean water, the Arctic sea ice bag is ending up being more delicate. In summer season 2020, ships quickly browsed the Northern Sea Route in ice-free waters, and even made it to the North Pole without much resistance.
Fortunately, summers are still not completely ice-free. “We have actually been hovering for a long time around 4 million square kilometers of Arctic sea ice each summer season,” stated Stroeve, a scientist at University of Manitoba. She included that she plans to take a look at which conditions and processes could press sea ice to the next “precipitous drop”– when the degree of summer season ice cover drops to a brand-new standard of 3 million square kilometers.
NASA Earth Observatory images by Joshua Stevens, utilizing data from the National Snow and Ice Data Center courtesy of Julienne Stroeve/Centre for Polar Observation and Modelling (CPOM).