Japan Aerospace Exploration Agency recorded what it believes is the fastest ever shrinking rate of the Arctic ice cap this summer, The Japan Times reports.

JAXA said Monday the Shizuku observation satellite indicated that the ice cap spans 4.66 million sq. km. as of Saturday. JAXA predicts that the ice cap will shrink as close to the 4.25 million sq. km. recorded in September 2007, the largest to date.

According to Masahiro Hori, a JAXA researcher and associate professor at Hokkaido University, the shrinking rate usually slows down by August but continues to shrink until late September. However, the pace accelerated this year.

“This is probably because the ice cover has become thinner in recent years and easier to melt away in the summer,” Hori added. The melting ice also increased the sea level at a faster rate.

The receding Arctic ice has paved the way for an expanding shipping lane through the Northern Sea Route. Vessels are usually towed by Russian-made ice-breakers which creates paths through the ice. Japan also considered using the Arctic route to lessen sailing costs and carbon emissions from fuel. Environmentalists argued against developing the Arctic Circle for navigation for fear of oil spill risks.