No, Antarctic sea ice data doesn't show 'global warming narrative is falling apart' | Fact check

The claim: Changes in Antarctic sea ice coverage shows global warming is not happening

A Dec. 28 Facebook post (direct link, archive link) shows two maps of Antarctic sea ice dated Dec. 26, 1979, and Dec. 25, 2023. The more recent map seems to show the ice occupying a larger area.

"Meanwhile the global warming narrative is falling apart," reads the post. "There is more sea ice around Antarctica now than there was in 1979."

The post was shared more than 50 times in two months.

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Our rating: False

Extensive evidence shows global warming is occurring, though scientists are uncertain whether it has begun to shrink the area occupied by Antarctic sea ice. While Antarctic sea ice did cover more area in late December 2023 than it did in 1979, it occupied less area for the rest of the year.

Antarctic sea ice recorded low in 2023

The annual average Antarctic sea ice extent – or the amount of area it covers – in 2023 was the lowest on record, Walt Meier, a sea ice scientist at the National Snow and Ice Data Center, told USA TODAY.

In 2023, Antarctic sea ice extent tracked below what it was in 1979 until Dec. 22, according to a National Snow & Ice Data Center data visualization tool. That means the post references one of only ten days in 2023 when sea ice extents were larger than in 1979.

The post is flawed for other reasons too.

Sea ice extent fluctuates seasonally and annually, Meier said, due to natural variations in the weather. Even if sea ice is declining overall, such as in the Arctic, each year doesn't necessarily have less ice than all previous years, he said.

"This is probably even more the case in the Antarctic because there is so much variation," Meier said. "The way to understand the changes in the ice cover is to look at the long-term trends. Comparing two random days − or months or years − does not provide any insight into sea ice conditions."

While the post implies the "global warming narrative" relies on the idea that Antarctic sea ice is in decline, major climate change research agencies have publicly reported that Antarctic sea ice is extremely variable and the overall trend in sea ice extent since 1979 has been nearly flat even though it is clear the Earth is warming.

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"For the most part, the Antarctic sea ice trend is flat," Meier said. "2023 was so low that the trend did go from very slightly positive to very slightly negative in most months. But effectively the trend has been zero."

That doesn't negate the reality of global warming, he said.

"Global warming is, well, global," Meier said. "In response to greenhouse gas emissions, the Earth as a whole is warming as expected − if not faster than expected. Within the global average, there is also expected to be a lot of variability. It doesn’t make sense that all regions are going to respond at the same pace."

However, the very low sea ice extent of the last few years, including the new record lows in 2023, have led some scientists to suspect global warming may be starting to impact the Antarctic sea ice extent. But it's too early to know for sure, Ella Gilbert, a climate modeler at the British Antarctic Survey, wrote in Carbon Brief.

"Deciphering the role of climate change in Antarctic sea ice trends is much more complicated than in the Arctic because conditions are impacted by so many competing factors," she wrote. "However, the sheer magnitude of 2023’s sea ice lows suggests that something unusual is happening."

Polar ice melt is only one piece of evidence that Earth is warming

While it is unclear whether global warming has begun impacting Antarctic sea ice, it is clear that global warming is happening. A long-term increase in average global atmospheric temperatures has been documented by multiple independent, international climate research organizations.

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Researchers have also detected warming of the world's oceans and documented the consequences of both marine and atmospheric warming, including:

Changes in the migration patterns, geographic range and behaviors of certain animal species provide additional evidence that Earth is warming.

USA TODAY reached out to the Facebook user who shared the post for comment but did not immediately receive a response.

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This article originally appeared on USA TODAY: Earth is warming, affect on Antarctic sea ice not clear | Fact check