There is less sea ice today in the Arctic and in the Antarctic than there has ever been before.
The area covered by sea ice in the Arctic was at just 13.19 million square kilometers in January 2017. While this may sound big, it's the smallest this area has been since the start of satellite recordings, according to the online "Meereisportal" or sea ice portal, an initiative run by several German research institutions.
It's also roughly 1.2 million square kilometers smaller than the long-term average measured from 1981 to 2010.
The situation isn't any better in the south, either. There is less sea ice surrounding Antarctica today than there was since reliable records began in 1979.
"As of Tuesday, it looks like we hit a new record low in the satellite era," Mark Serreze, the director of the National Snow and Ice Data Center, told US broadcaster CNN on Thursday.
The extent to which the ice at the poles is melting is considered an indicator as well as a consequence of global temperature rises.
"The annual freeze and thaw of sea ice in the polar regions is like the beating heart of our planet, driving ocean circulation and regulating our climate," Rod Downie, Polar Program Manager at the World Wide Fund for Nature (WWF), wrote in an email to DW.
Air temperatures are climbing and so are water temperatures. The ice is melting faster because of that - and it does so later into winter as well. So the period of winter where the water is actually cold enough to freeze is getting shorter, which means the ice floes are getting smaller.
But the amount of ice also regulates global temperatures, since water in the seas absorbs heat, whereas ice would reflect it back into space. So with less ice, temperatures are rising even more - it's a vicious circle.
The amount of Arctic sea ice was alarmingly low in January, the National Snow and Ice Data Center reported. 2016 was the warmest year on record around the North Pole, with a heat wave hitting in December, and that trend does not appear to be letting up in 2017.
"After studying the Arctic and its climate for three and a half decades, I have concluded that what has happened over the last year goes beyond even the extreme," Serreze wrote in an essay for Earth magazine.
In Antarctica, long regarded as immune to climate warming, scientists have also monitored changes.
Experts across the world are shocked by how much smaller the area covered by sea ice in the Antarctic is today than it was just a few years ago.
They are calling for swift action.
"The Paris Agreement [which aims to keep the global temperature increase lower than 2 degrees Celsius above pre-Industrial times] has to be implemented as fast as possible," Sybille Klenzendorf, a WWF expert, told DW. "We can still manage to make our goals, but the clock is ticking."
WWF's Polar Program Manager Downie stressed that the decline of sea ice in both Arctic and Antarctic will have dire consequences for humans and many other species.
"That is bad news for wildlife from blue whales, polar bears and penguins to krill and the many thousands of other species that have evolved to live, on, under or around sea ice," he stated. "And it's bad news for the people of the Arctic and across the world. We need to urgently reduce our carbon emissions and tackle climate change head-on."