Arctic ice melt has slowed despite record heat. Is that a good sign?

The scientific research vessel Kronprins Haakon moves through a fjord covered with sea ice in eastern Spitzbergen on April 6.
(Olivier Morin/AFP/Getty Images)  

 

From Washington Post by Kasha Patel

The slowdown may continue for another five to 10 years, though later on, sea ice could melt faster than the long-term average

The melting of Arctic ice has been one of the most profound ripple effects from climate change, an impact often depicted with images of a lone polar bear stranded on a dwindling piece of sea ice.
Now, a new study has found that ice has been melting more slowly over the past two decades across all seasons — even under a record-hot atmosphere.

From 2005 to 2024, scientists say Arctic sea ice has been declining at its slowest rate for any 20-year period since satellite measurements began in 1979.
Using two different datasets, the team found that the melt rate over the past 20 years has been at least twice as slow as the longer-term rate.

The slowdown is temporary, models show.
It may continue for another five to 10 years, and afterward, sea ice may melt faster than the long-term average — offsetting any short reprieve that we may have had.

“Even though there is increased emissions [and] increased global temperatures, you can still get periods where you have very minimal loss of Arctic sea ice for sustained periods,” said Mark England, lead author of the study, published this month in Geophysical Research Letters.

Here’s what to know about variations in how ice declines in the Arctic.

Why is Arctic ice melting more slowly in recent decades?

Let’s boil the factors influencing Earth’s climate down to a simple equation: humans and the planet’s natural cycles.

Human activities are unequivocally warming the planet by releasing greenhouse gases, which trap heat in our atmosphere and accelerate ice melt.AI Icon

But while climate change has been the overriding factor driving ice decline, scientists say natural variations on Earth — such as El Niño or the Atlantic Multidecadal Oscillation — can also have different effects on our environment across time.

The most common driver in Earth’s natural cycles is the difference in how much energy is exchanged between the ocean and atmosphere, said Alex Crawford, an assistant professor of environment and geography at University of Manitoba in Canada who was not involved in the study.

“There’s always energy going back and forth between the atmosphere and ocean,” Crawford said.
“For various reasons, the oceans can store much, much more energy than the atmosphere.”

In some years, he said the world’s oceans take in a little more energy than normal, which will make the global atmosphere cooler than normal.
If the oceans take in a little less energy than normal, the global atmosphere will be warmer than normal.

“The most famous example of this is El Niño and La Niña, but there’s also longer-term variability that can take place over several decades and either amplify (e.g., the 2010s) or weaken (e.g., the 2000s) the global warming trend,” Crawford said.
“This is all normal.”

Over the past two decades, England said the planet’s natural cycles perhaps helped create cooler waters around the Arctic that favored sea ice growth.
Still, added heat from human activities has counteracted this growth and led to an overall deficit.

For perspective, without climate change, these natural variations perhaps would have even caused the sea ice to grow in these past two decades, England said.

How rare is this slowdown in Arctic ice melt?

Even with high greenhouse gas emissions, scientists have found that periodic slowdowns do occur.

In the study, the team analyzed past climate models that showed these slower ice losses over the past two decades.
They found these slowdowns occurred about 20 percent of the time in simulations.

“This isn’t some infrequent rare event. This is something which should be expected as a part of the way that the climate system evolves,” said England, who conducted the study as a senior research fellow at the University of Exeter and is now an assistant professor at the University of California at Irvine.

In addition, the team found the current slowdown has a 50 percent chance of lasting for five more years and a 25 percent chance of lasting another 10 years.

Polar scientist Alexandra Jahn, who was not involved in the research, said her own work showed slower Arctic sea ice melt occurred commonly across 10-year periods — even in the presence of human-caused warming.

After this slowdown episode ends, Jahn said, “eventually we’ll see a decline again.”

Does this slower ice melt mean climate change is slowing down?

Multiple factors make clear that climate change is not slowing down.
Carbon dioxide concentrations are still at their highest levels in human history, growing at their fastest rate in our observed records.
Earth’s hottest years have all occurred in just the past decade, with multiple record years in the Arctic.

“If you look at global temperatures, they are definitely not slowing down,” England said.
“The debate now is whether they are speeding up.”

Additionally, climate models showed these slowdowns are possible even in a world that continues to warm.
Similar to the past two decades, Earth’s natural cycles may favor more ice growth and slow down melting.

Think of the Arctic sea ice trend as a ball rolling down a hill, explained climate scientist Ed Hawkins.
The ball may hit some bumps that slow it down, but it will be heading toward the bottom as greenhouse gas emissions continue.

Is Arctic ice in good health now?

Even though the rate of Arctic ice melt has slowed, ice is still declining in large quantities.

Using two different datasets, study authors found the melt rate over the past 20 years has been about 0.35 million and 0.29 million square kilometers per decade (depending on the dataset).
Since 2010, the team found, the volume of ice loss amounted to about 0.4 million cubic kilometers each decade.

Overall, sea ice conditions at the end of the summer are at least 33 percent lower now than they were 45 years ago.

The decades-long loss of ice has increased ship traffic in the region, making travel easier for tourists and ships.

Communities around the Bering and Chukchi seas have reported substantial die-offs of sea birds, such as ducks and puffins, probably due to starvation and low sea ice.
The sea ice retreat has forced Indigenous hunters to travel farther and spend more time hunting walruses and bowhead whales, also facing higher waves because of less sea ice.

Although the Arctic is low, England said it’s better than the area being completely ice-free.
But he expects an accelerated loss once this period subsides.
On average, he said sea ice loss has amounted to about 0.8 million square kilometers per decade over the long term.
The subsequent ice melt could be 0.6 million square kilometers per decade faster than the broader long-term decline, the study found.

“This temporary period can’t go on forever,” England said.
“It’s bit like a kind of sugar rush.
It feels good … and at some point it will kind of crash.”