Recent Arctic Sea Ice Decline Is Not Accelerating

It is time to return to examining the relationship between atmospheric carbon dioxide and the average surface area of northern polar ice in September of the previous year. I therefore once again conducted a regression analysis of the relationship between these two variables—over the period from 1979 to 2025—using carbon dioxide concentrations measured at Mauna Loa and ice area data from the NSIDC.

Since 2018 (using data from 2017), the basic idea underlying the analysis I have carried out annually is derived from the following premises: (1) according to the climate change hypothesis, climate change is an accelerating process; (2) models predict that temperature increases in the Arctic will be faster than in the rest of the globe; and (3) changes in polar ice area serve as a good proxy for temperature changes in the northernmost parts of the Earth.

In the figure below, the years marked in blue indicate those starting points from which annual measurements have demonstrated the existence of such a relationship according to the criterion I use (P < 0.01 in two consecutive years). The height of the bars shows how many years after that starting point this statistical significance was achieved.

The years marked in red are those for which no such statistical significance has been found. In these cases, the height of the bars indicates the number of years available for the analysis.

As my esteemed reader notes, during the early years of the time series the minimum extent of polar ice decreased in such a way that—according to the regression analysis—it exhibited a clear statistical cause-and-effect relationship with atmospheric carbon dioxide concentrations. Moreover, this relationship strengthened almost year by year up to the time series beginning in 2001.

After that, however, a change occurred: although atmospheric carbon dioxide concentrations continued to rise steadily, the change in ice area did not reach statistical significance until last year. At that point, the observational series beginning in 2002 also became statistically significant, but only on the basis of an observational record twice as long as that required for the series beginning in the previous year.

This year, what was new was that the time series beginning in 2003 also reached statistical significance. It can therefore be concluded that northern sea ice has indeed melted in a statistically significant manner in recent years as well, but that the process—at least as measured by its annual minimum extent—has not been accelerating, as climate models have predicted.

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In this respect, it is also interesting that although Arctic sea ice reached a larger minimum extent this year than in six other years (2007, 2012, 2016, 2020, 2003, and 2024), it melted rapidly in October, November, and December, and its surface area reached the smallest December average in the measurement record last month. This is shown in the figure below (the early part of which admittedly raises questions, but for which I am unable to provide an explanation).

Previous thoughts on the same topic:
Observations on Arctic Sea Ice Challenge the Notion of Particularly Rapid Melting
Exceptionally Warm July Falls Short of Records
Exceptionally Warm July Falls Short of Records

The original blogpost in Finnish:
Pohjoinen merijää sulaa sittenkin

Reevaluating Arctic Sea Ice Melt: A Closer Look at Trends and Predictions

According to a recent survey, as many as 70 percent of Finnish schoolchildren suffer from mental health issues. A significant cause of this is the news coverage related to climate change and the environment, which has driven even the most gifted young people into deep anxiety.

For this reason, I once again decided to analyze the melting of Arctic sea ice, which has been claimed to result in ice-free waters by the 2030s. Based on the statistics, I created the following image using data from the National Snow and Ice Data Center's dataset "All daily (single day and five-day trailing average) extent values in one file, updated daily," which officially begins in 1987 (prior to this, the dataset only contains data for every second day).

From this dataset, I extracted the minimum extent of Arctic ice for each year and plotted the following image, which shows the annual minimum extent of Arctic ice, its five-year moving average, and a linear trendline generated by Excel, which I manually extended across the entire chart.

From the red five-year moving average, it can be seen that the ice melt can be divided into three phases. From the start of the dataset until the mid-1990s, it was slow, but then accelerated for over a decade, reaching its minimum in 2013. After that, the melting slowed down again.

The black regression curve drawn on the chart for the entire dataset, however, shows that if the trend were to continue as it has in the recorded data, the Arctic sea ice would likely not be ice-free even by 2050. Therefore, the melting predicted by climate scientists for the 2030s must be based on other factors.

To understand this, I drew another image, in which I manually fitted a straight line that follows only the rapid melting phase in the middle of the dataset, aligning with the red five-year moving average. This appears as a green line in the image below.

As my esteemed reader will notice, this line corresponds to the scientific prediction of ice melt in the near future. Thus, it seems that the forecast in question—despite being mathematically and scientifically complex—is ultimately based on a development that would occur if the ice melt follows the trend from the late 1990s to 2013.

But what about the events in Arctic sea ice melting after 2013? To understand this, I performed a similar manual line fitting operation based on the post-2013 data. This is shown as a blue line in the diagram below.

As my esteemed reader will notice, this "data fit" also indicates a downward trend, but a very gradual one. And if this trend prevails in the Arctic, no living person today will witness an ice-free Arctic Ocean. Not even their children.

Therefore, I would hope that media coverage of climate change, and especially the melting of Arctic sea ice, would be less sensationalist and instead highlight the factors that suggest extreme views are unlikely to materialize. These also indicate that the models predicting rapid climate change still involve vast uncertainties, suggesting that humanity most likely has ample time to adapt to the ever-changing environment.

Previous thoughts on the same topic:
Climate Model Predictions and the Reality of Arctic Sea Ice
Can climate models predict the distribution of warming?
The area of Arctic sea ice was exceptionally large in January