Examining the remote St. Matthew island off Alaska, scientists found that this year saw the summertime Arctic sea ice hit its lowest level for July in 40 years of record keeping, according to the study published in the journal Science Advances.

Although sea ice builds up again each year during the winter, the new study suggests that, in the Bering Sea, cold-season ice maximums may also be in decline.

Except from the vast impact on Arctic wildlife and subsequent consequences for indigenous communities, shrinking sea ice also exacerbates warming in the region, as ice is replaced by patches of dark water that absorb solar radiation rather than reflecting it back out of the atmosphere.

Obviously, if we lose the sea ice you are completely changing the temperatures of the Arctic. If you lose it all, you’re going to warm up the region even faster,

...explains Julienne Stroeve, a climatologist with National Snow and Ice Data Center at the University of Boulder Colorado not involved in the study.

See also: New shipping routes in the Bering Sea and Bering Strait

Air temperature wasn’t the only factor found to be affecting sea ice, though. Shifts in ocean and atmospheric circulation linked to climate change have an even bigger impact, added lead author Miriam Jones, a geologist at the US Geological Survey.

There’s a lot more going on than simply warming temperatures. We’re seeing a shift in circulation patterns both in the ocean and the atmosphere,

...Jones said.

Finally, the study noted that changes in sea ice appeared to lag at least several decades behind changes in atmospheric greenhouse gases. That implies that the recent lows in winter sea ice were a response to GHG levels decades ago.