Kate S. Petersen, USA TODAY
Mon, May 30, 2022
The claim: Images show floating Arctic sea ice has hardly changed in decades
Arctic sea ice, which is frozen sea water that floats on top of the ocean's surface, grows and melts during the year. Like ice sheets and glaciers, Arctic sea ice is disappearing because of climate change.
Arctic sea ice minimum extent – its size at the end of the summer melt – has declined 13% per decade since the late 1970s, according to the National Snow & Ice Data Center and NASA data.
However, some social media posts use images from the National Snow & Ice Data Center's public online data tool, Sea Ice Index, to suggest that Arctic sea ice extent has not meaningfully changed in decades.
For example, one social media post includes two images that supposedly illustrate little change in/ Arctic sea ice extent. One is labeled "13 May 1989." The other is labeled "13 May 2022." The images appear very similar.
"See a difference worth losing sleep? Neither do I. Yet, every few days I see in the press that 'as the Sea Ice continues to disappear' yah da yahda," reads the caption of a May 14 Facebook post featuring the images.
The post was shared more than 1,500 times in four days.
However, the post is misleading. Although Arctic sea ice is declining overall due to human behavior, it is still possible for two individual days, years apart, to have similar sea ice coverage, according to researchers. This is because Arctic sea ice extent is variable and informed by season and weather patterns, not just long-term climate trends. However, the overall downward trend is clear.
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USA TODAY reached out to social media users who shared the claim for comment.
Sea ice extent variable across seasons and years, but still declining overall
Arctic sea ice change can only meaningfully be measured in terms of long-term trends, not its status on two individual days, Bonnie Light, the chair and senior principal physicist at the University of Washington Polar Science Center, told USA TODAY.
"Picking single days out of two different years in a climate record is not informative," she said in an email. "It would be analogous to saying that it was raining on 19 May 1989 but then sunny on 19 May 2022 and therefore rain – at that particular location – has lessened or stopped entirely."
Satellite surveillance since the late 1970s shows that Arctic sea ice is clearly declining, but that doesn't mean that each day there is less ice than the day before.
This is because Arctic sea ice extent is impacted by long-term climate trends, such as the warming caused by human behavior, but also by weather and other natural variability in Earth's climate systems, according to Walt Meier, a senior research scientist at National Snow & Ice Data Center.
In 2021, for example, weak summer cyclones brought cloudy, cooler weather to the Arctic, which helped slow sea ice melt, Meier told USA TODAY in an email. This resulted in the September 2021 minimum extent being larger than the previous year – seemingly defying the downward trend.
However, the average minimum extent for the decade between 2011-2020 was roughly 36% smaller than it was between 1981-1990, according to data Meier provided.
Fact check: Short term global temperature fluctuations do not negate climate science, overall warming
It is these longer-term trends that researchers have identified as being caused by human-driven climate change.
Post cherry-picks misleading data
While sea ice extent has declined in all months, some months have been more impacted than others thus far, Light said.
This means the social media claim, which compares a date in May 2022 to the same date in May 1989, is particularly misleading.
May is a month that has exhibited less extent loss over time than other months, such as August, September and October, according to National Snow & Ice Data Center data.
Because of this, "May is a much easier time to find similar days in 1989 and 2022, than September," Meier said. Further, May of 1989 had the lowest extent of any May between 1979-2001, making it particularly easy to find a comparable day in 2022.
Another issue is that the National Snow & Ice Data Center images used in the social media post, show sea ice extent, but not volume – which has also been decreasing.
Thus, comparing only the extent data from two timepoints decades apart is misleading because the total amount of ice present is likely to be very different, even if the extent is roughly the same, said Meier.
Fact check: NASA did not deny warming or say polar ice has increased since 1979
"You can’t cherry-pick two years and then cherry-pick two days within those years and make any kind of conclusive comparison," he said.
Loss of sea ice exacerbates global warming
Long-term Arctic sea ice losses exacerbate global warming through the Arctic ice-albedo feedback cycle.
Sea ice reflects more of the sun's energy than water – it has a higher albedo.
Fact check: False claim that Arctic, Antarctic ice reached record highs
Therefore, as ice coverage decreases, more and more of the sun's energy is absorbed by the ocean – warming it up.
"The more ocean exposed, the larger the potential for absorption of sunlight directly into the ocean, which fuels further ice melt," Light said.
Our rating: Missing context
Based on our research, we rate MISSING CONTEXT the claim that images show Arctic sea ice extent has hardly changed in decades. Arctic sea ice has declined significantly since the late 1970s. However, sea ice extent is still variable due to seasonality and weather patterns. The extent on two individual days is not adequate to establish a pattern, according to researchers. This claim is based on cherry-picked data from a year with a lower than average extent during a time of year when ice losses are relatively minimal.
Our fact-check sources:
Bonnie Light, May 19, Email exchange with USA TODAY
Walt Meier, May 20, Email exchange with USA TODAY
AFP, May 18, Facebook post misinterprets data to suggest Arctic ice is not declining
NASA Vital Signs of the Planet, accessed May 18, Arctic Sea Ice Extent
National Snow & Ice Data Center, accessed May 18, Sea Ice Index
National Snow & Ice Data Center, April 3, 2020, Thermodynamics: Albedo
NASA, April 20, 2020, Ice-Albedo Feedback in the Arctic
Polar Science Center, accessed May 19, Home page
NASA Vital Signs of the Planet, accessed May 19, The Effects of Climate Change
NASA Vital Signs of the Planet, accessed May 20, Ice sheets
NASA Vital Signs of the Planet, accessed May 23, The Causes of Climate Change
National Snow & Ice Data Center, accessed May 23, Sea Ice Index: Compare trends
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This article originally appeared on USA TODAY: Fact check: Arctic sea ice declining, cherry-picked data misleading
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