Arctic sea ice has shrunk to the point of lowering its winter extent as global temperatures crash.

WASHINGTON (AP) – Crucial Arctic sea ice has shrunk to record its lowest point in the winter, the season when sea ice is growing, as global warming breaks records across the continents.

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Arctic sea ice conditions, especially in summer, are important to the Earth’s climate because without the ice reflecting sunlight, more heat is absorbed into the oceans. All the ice that surrounds the poles acts as the Earth’s refrigerator. Wildlife, such as bears and seals, also depend on sea ice. The lack of sea ice in the Arctic creates new shipping lanes and in doing so creates political disruption, making once-neglected places like Greenland more desirable.

Shrinking Arctic sea ice was announced Thursday as temperatures broke March temperature records across the United States, across Mexico, Australia, across North Africa and parts of Northern Europe. Meteorologist and climate historian Maximiliano Herrera, who tracks extreme temperatures, called March’s extreme heat “the most extreme heat event in the history of global climate” and said on social media that the next few days will be “even more intense.”

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Sixteen states broke March temperature records in the past week or so, said climate historian Christ Burt. Twenty-seven locations had temperatures last week high enough to tie or exceed the hottest April day on record, including St. Louis, meteorologists said. Mexico has broken thousands of records, some of them hotter than the May heat, but that is nothing compared to what is happening in Asia, where “thousands of thousands of monthly records” have been broken by 30 to 35 degrees (17 to 19 degrees Celsius), Herrera said.

Yet at the same time earlier this week, Antarctica set a record for the coldest March day anywhere on Earth at 105.5 degrees (minus 76.4 degrees Celsius), according to Herrera and Burt.

Steady decline in sea ice

Each year the Arctic sea ice grows during the cold winter and shrinks during the summer heat. This year growth was so small that its peak, before it began to decline, was 5.52 million square kilometers (14.29 million square miles). That’s slightly less than last year’s 5.53 million square kilometers (14.31 million square miles), but the National Snow and Ice Data Center, which does the measurements, considers the two numbers close enough to be a tie.

This year’s sea ice extent was 525,000 square kilometers (1.36 million miles) less than the average winter peak of 1981 to 2010. It is almost twice the size of Texas.

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“As temperatures warm and continue to warm, especially in the polar region, there is less opportunity for ice to grow and on average it will decrease,” said the center’s senior scientist Walt Meier. “It’s not like we’re seeing a regime change or anything. It’s a steady decline in the winter and the worst. And it also gives us the title of the summer thaw. We’re starting from a low number.”

Summer sea ice is key

The summer melt period — which precedes the September measure known as minimum Arctic sea ice — is “a very important time,” Meier said. Another reason is that when there is little white ice that indicates a strong summer sun, the oceans can absorb a lot of heat. And when that happens, the Arctic warms up along with the temperature in the south and changes in atmospheric pressure. A leading theory – which is still being debated – says that those changes in the Arctic then change the movement and shape of the jet stream, which drives the weather west to east and contributes to severe weather explosions, he said.

Melting sea ice does not help raise sea levels.

The growth period of winter sea ice also changes more with climate changes, so just because the Arctic hits a record low in March, it doesn’t mean the summer will decrease, Meier said.

“The winter conditions are really impressive,” Meier said. “It is, I would say, a sign of climate change of global warming.”

On the other side of the planet, Antarctic sea ice is greatly affected by the region’s climate and ocean conditions. In February, Antarctica reached its lowest level of the year and while it was less than the 30-year average, it was nowhere near the low levels of the past three years, Meier said.