Falling snowflakes in the Arctic are trapping extra heat, which could be enough to speed up the melting of sea ice. The effect could mean Arctic seas become ice-free up to 20 years earlier than expected.
鈥淚t鈥檚 counter-intuitive because we think of snowflakes as being cold, but they鈥檙e slow-falling ice particles that act like blankets,鈥� says Frank Li of the Jet Propulsion Laboratory in Pasadena, California.
Sea ice in the Arctic tends to melt faster than forecast. So the team compared the few climate models that take snowflakes into account with the many that don鈥檛 to see if it could partly explain the difference.
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The group found that the extra heat trapped by snowflakes makes sea ice on average 0.3 metres thinner, making it more vulnerable to melting away in summer.
The first ice-free Arctic summer
Climate change is melting the Arctic sea ice, which has been shrinking for decades. In January 2017, the area of the global sea covered by ice hit its lowest level on record.
The loss of the Arctic sea ice may threaten animals like polar bears, which rely on the ice to hunt, and there are also knock-on effects for weather and ecosystems elsewhere. At some point this century, the Arctic Ocean is expected to experience its first ice-free summer for three million years.
The team also simulated changes in the ice until 2100, using a model that represents falling snow and assuming that we continue emitting lots of greenhouse gases.
Existing models predict the first ice-free Arctic summer when carbon dioxide聽concentrations reach 680 parts per million, which will occur around 2072. However, the model suggested that the heating from snowflakes could bring it forward to 2052, when CO2 would only be at 550 ppm.
This is not proof that Arctic sea ice will disappear faster than thought, says Li. It could be that other undiscovered processes will slow the retreat. 鈥淏ut we鈥檝e found an important process that really seems to matter,鈥� he says.
The Cryosphere
