For more than half a century, the melting of sea ice in the Arctic has been among the most well-known indicators of climate change. But a new study has revealed that the pace of sea ice loss has slowed down in the past 20 years.This does not mean that the Arctic sea ice is rebounding. The slowdown is only temporary and may continue for another five to 10 years, after which the sea ice may melt faster than the long-term average, the study said.The research was conducted by M R England of the University of Exeter (the UK) with his colleagues J Screen and A C Chan, and L M Polvani of Columbia University (the US). Titled ‘Minimal Arctic Sea Ice Loss in the Last 20 Years, Consistent With Internal Climate Variability’, it was published in the journal Geophysical Research Letters earlier this month.England, now at the University of California, Irvine, has told The Indian Express over email that the findings do not affect “fundamental science and urgency for climate action… Multi-decadal fluctuations in ice loss rates do not reduce the need for immediate action to mitigate climate change impacts.”Why has Arctic sea ice loss slowed down in the last 20 years?It has long been established that human activities — primarily, the burning of fossil fuels that emits heat-trapping greenhouse gases (GHG) — have led to a rise in global temperatures. In the Arctic, this warming has led to the melting of sea ice.Research has shown that the region has lost more than 10,000 cubic kilometres of sea ice since the 1980s (‘Arctic sea ice thickness, volume, and multiyear ice coverage: losses and coupled variability 1958–2018’, Environmental Research Letters, 2018).Anthropogenic global warming, however, does not do away with natural variations in the Earth’s climate system (although it can affect these). One such variation is the El Niño-Southern Oscillation (ENSO), which refers to a fluctuation in sea surface temperatures (SSTs) in the equatorial Pacific Ocean that occurs every two to seven years. ENSO influences, alters, and interferes with global atmospheric circulation, which, in turn, influences the weather worldwide.Story continues below this adEngland suggests these natural climate variances could be behind the slowdown in the melting of Arctic sea ice.“For the purpose of our study, we would be thinking of climate variations on a longer timescale, such as the Pacific Decadal Oscillation, which is similar to ENSO but on a longer timescale, and Atlantic Multidecadal Variability (a fluctuation of SSTs in the North Atlantic). These climate variations can bring anomalously cool waters into the Arctic region and lead to less loss of sea ice or expansion in some areas,” he said.According to the study, the melt rate over the past 20 years has been around 0.35 square kilometres per decade, compared to the peak rate between 1993 and 2012, which was at least four times higher, closer to 1.3 million square kilometres per decade.Does this mean that climate change is also slowing down?Humans continue to release unprecedented levels of GHG into the atmosphere, and mean global temperatures continue to rise. There is thus no indication that the slower Arctic sea ice melting implies that climate change is also slowing down.Story continues below this adAlso in Explained | 2024 was the warmest year for India and the world. But why was warming lower over India?England and his colleagues used climate models, which simulate the historical period and explore different future warming scenarios, and found that such slowdowns in the melting of sea ice are expected to occur frequently. In fact, even under high GHG emissions, periodic slowdowns do take place.They also revealed that the current slowdown is only temporary and there is a 50% chance that it lasts for five more years, and a 25% chance that it lasts another 10 years.Think of Arctic sea ice extent behaving like a ball bouncing down a hill, England said.“There are periods in which the ball may bounce down the slope, come off at an angle and temporarily have a near flat trajectory or even appear to be climbing. But we know that at some point, gravity will bring the ball hurtling down the slope,” he said.Story continues below this adJust like the ball, Arctic sea ice loss may temporarily seem to defy expectations at present, but the melting will ultimately resume.The study highlights that once the slowdown stops, there is a risk of a more rapid decline in sea ice cover in the coming years. It has shown that for the five years after the end of the slowdown, there is an additional 0.6 million square kilometres per decade of sea ice loss.“In this case, when the ball starts to move towards the ground (this is analogous to when climate variability switches from contributing to sea ice growth to sea ice loss), it will do so at a rapid pace. What we find is that whenever the slowdown ends, the models suggest that the pace of ice loss will be substantially faster than the longer-term trend,” said England.The loss of sea ice in the Arctic would have far-reaching consequences. It will exacerbate global warming, lead to further rise of sea levels, and present unprecedented challenges to ecosystems that are dependent on sea ice.