Arctic sea ice has hit a record low for its maximum extent in winter, which scientists said was a result of climate change and abnormal weather patterns.

The US National Snow and Ice Data Centre (NSIDC) said on Thursday that at its peak the ice covered just over 14.5m sq km of the northern seas. This was 130,000 sq km smaller than the previous lowest maximum in 2011.

The peak occurred on 25 February, which the NSIDC’s senior research scientist Ted Scambos said was “very early but not unprecedented”.

Climate change is driving declining ice coverage in the Arctic, with a recent study finding it has also become significantly thinner, down 65% since 1975.

Scambos said northern oceans have progressively warmed because of climate change. This winter, the warmer seas combined with mild weather to create exceptionally poor conditions for the annual freeze.

“[The record low extent] is significant, in that it shows that the Arctic is being seriously impacted by our warming climate,” said Scambos. “In general, sea ice retreat has proceeded faster than modelling expects in the Arctic, although models are catching up.”

Bob Ward, at the Grantham Research Institute on Climate Change and the Environment at LSE, said: “This is further evidence that global warming and its impacts have not stopped despite the inaccurate and misleading claims of climate change ‘sceptics’.

“Over the past few weeks, there has been an increase in the amount of misinformation from climate change ‘sceptics’ in the UK and elsewhere which is intended to mislead the public and policy-makers into believing that the effects of global warming on the polar regions are absent or negligible.”

The most pronounced deviation from the 1981-2010 average cover was in the Bering and Okhotsk seas in the northern Pacific. There, the ice edge was 100-200km further north than in a normal year.

After March the summer thaw will begin, with the ice retreating towards its summer minimum, which usually occurs in September. The summer ice cover in the Arctic is also on a long-term decline, although Scambos says a low winter maximum does not necessarily indicate a low minimum is on the way.

The loss of ice from the Arctic has raised questions over when the region will experience its first ice-free summer. Scambos said he expects the summer minimum to dip below 1m sq km (386,100 sq miles) within the next 15 years. At this stage, he said, the Arctic will be profoundly changed.

“A less than 1m sq km summer would mean that the north pole would be open water, that a broad seaway would exist north of Siberia and that major ecosystems and fauna would be severely impacted. My own guess is that we will reach this level around 2030.”

The absence of sea ice and abnormally mild weather affects communities and wildlife in the Arctic circle, which are adapted to extreme conditions.

In Svalbard, Kim Holmén, the international director of the Norwegian Polar Institute, said the fjords there remained unfrozen and instead of the normal snowfall the island experienced rain which froze when it hit the ground.

“Much of Svalbard is covered with ice on land, which is a fatal state for the reindeer. When the landscape is covered by ice they can’t move around and they can’t eat.”

Too much ice on the land and none in the sea has also made life difficult for the 2,600 people who live on Svalbard.

“This iced landscape is miserable to travel across on your snowmobile and your skis,” said Holmén. “We can’t ride our snowmobiles across the fjord so there are places where people want to go that they can’t go. We have had tragic events with avalanches. Living in Svalbard we’ve always had avalanches but we’ve had one casualty this winter. Some of the risks are changing because we have more icing events.”

He said this type of weather is expected to become normal under a changing climate.

“This winter is an example of what we believe will become more common and has profound influence on the reindeer and the ptarmigan [a species of bird] and other creatures that roam the land,” he said.

This week, on the opposite side of the Arctic Ocean, Alaska’s Iditarod sled race was forced to shift its start 362km (225 miles) further north due to a lack of snow. This has only happened once before in the race’s 43-year history, in 2003.

Meanwhile, the NSIDC said ice floes surrounding Antarctica reached a relatively high summer minimum on 20 February. The extent of ice was 1.38m sq km, the fourth largest on record. Antarctic sea ice has confounded some scientific modelling by growing in recent years. There are several theories why the extent of the ice is growing despite a general warming trend across the southern continent.

“This is a matter of considerable debate,” said Scambos. “The important thing to say is that the Antarctic is most definitely seeing the effects of warming and circulation changes – it is participating in ‘global warming’ in its own way. There are several effects in play. Primarily it seems that increased strength in low-pressure areas near the Ross and Weddell seas are pushing ice outward from the continent.”