Know about five sigma event happening in Antarctica due to climate change

Antarctic sea ice, which has historically been able to recover during the winter, is now experiencing an alarming decline. This winter has seen an unprecedented trend, as sea ice around Antarctica has not returned to expected levels, leaving scientists puzzled and concerned about its future recovery.

In previous years, the sea ice extent of the frozen continent would substantially recover during the winter months, when Antarctica is shrouded in darkness and low temperatures. However, this year has defied expectations, as the recovery process has not taken place, which has had important implications.

This cycle regulated the planet's climate and distributed nutrient-rich water to other oceans while supported a plethora of life, from penguins and seals to tiny krill and algae.

Right now, however, sea ice extent measured just 2.7 million square kilometres below the 1991-2020 mean.

“The mean is five sigma, or standard deviations, below, which is well outside its normal range of variability," said Professor Tim Naish, a leading glaciologist, climate scientist and the director of Victoria University’s Antarctic Research Centre.

The chance in statistical terms is roughly one-in-7,400,000. If you had predicted it, you would have won Lotto.

Naish said, "Most expert groups are suggesting that a human-induced global heating is highly likely the cause, as winter sea ice extent is now so far outside the window of natural variability."

The southern polar atmosphere and ocean systems are highly complex and poorly understood.

Rare 'five sigma' Antarctic event

Experts call this event a "five sigma" phenomenon, meaning it is a statistical oddity of five standard deviations beyond the mean. In context, one would expect such an occurrence to happen only once every 7.5 million years if no changes had occurred, which makes it an amazing and rare event.

Physical oceanographer Edward Doddridge has been closely monitoring drastic changes in Antarctica and has described vast regions of the Antarctic coastline as ice-free for the first time in recorded history, emphasizing that the situation is truly unprecedented.

Dr Doddridge said, "If there is less ice, the ocean's surface absorbs the sunlight that hits it instead of reflecting it out into space."

"The warming accelerates in that area, and it carries the warmth around to the rest of the world."

Sea ice plays a vital role in regulating Earth's temperature through a process known as ice albedo feedback. When there is less ice, sunlight that hits the ocean surface is absorbed rather than reflected back into space. This leads to accelerated warming in the region, which in turn has far-reaching consequences, affecting global temperatures and the ocean currents that carry nutrients and sustain ecosystems.

In addition, sea ice serves as crucial habitat for several species of wildlife, including penguins, seals, and krill, which form the foundation of the Antarctic food web.

Prof. Eliot Jacobson tweeted, "Wow, just wow. The planet is breaking. Antarctic sea ice extent is the headline for me this morning. There was actually a net decrease in ice extent day over day, and it's mid-winter there, peak freeze season. Extent is now 6.4 standard deviations below the 1991-2020 mean."

What is five-sigma event?

An extremely rare and unlikely occurrence, often considered to be highly significant in scientific research and data analysis, describes a five-sigma event. In the context of this news article about the declining Antarctic sea ice, the term "five-sigma event" refers to the unprecedented and exceptional nature of the sea ice not substantially recovering during the winter.

In statistical analysis, sigma is a measure of standard deviation, which quantifies how much individual data points deviate from the mean or average value. A five-sigma event indicates a statistical anomaly five standard deviations away from the mean, making it an exceptionally rare event with a very low probability of happening by chance. Researchers find the occurrence so infrequent that it is unexpected and highly significant in practical terms.

Declining Antarctic sea ice: Impact

The significant decline in Antarctic sea ice has far-reaching and multifaceted consequences for the planet and its inhabitants. It accelerates global warming as less ice disrupts the ice-albedo feedback mechanism, leading to increased absorption of sunlight by the dark ocean waters.

This, in turn, contributes to the overall warming trend. The annual freeze and melt cycle in Antarctica drives global ocean currents, sustaining marine ecosystems worldwide, but the decline in sea ice could disrupt these currents, affecting marine life and food chains.

Sea ice also provides essential habitat for penguins, seals, and krill, threatening their survival and impacting the entire Antarctic food web and marine biodiversity. Furthermore, melting ice sheets and glaciers contribute to rising sea levels, posing a significant threat to coastal communities.

The decline in sea ice could trigger tipping points in the climate system, resulting in abrupt and irreversible changes affecting weather patterns, ecosystems, and human societies. We urgently need global climate policy to reduce greenhouse gas emissions and mitigate the impacts of climate change, emphasizing the critical need for immediate action.

Human-induced climate change suspected

The significant decline in sea ice around Antarctica has raised concerns among scientists about the factors that contribute to this phenomenon. While some consider natural variability a possibility, the consensus among experts is that human-induced climate change is the most likely culprit. It is believed that the increase in temperatures both in the atmosphere and in the seas is upsetting the delicate balance of the Antarctic ecosystem.

Scientists are now urgently investigating the root causes of this decline. Petra Heil, a sea ice physicist with the Australian Antarctic Division, emphasizes that the entire system interconnects, and changes in one component can have cascading effects throughout the region.

"The whole system that we are looking at, we know it's strongly coupled," Dr Heil said.

The entire system couples with changes in any of its components, whether they occur in a distant or nearby region within the studied area.

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