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Frequent heatwaves have become the norm in the Arctic Ocean

In recent years, the Arctic Ocean has been facing an unprecedented environmental challenge that is set to redefine its landscape. A groundbreaking study led by Dr. Armineh Barkhordarian from Universität Hamburg has shed light on a distressing trend that has become a new norm in the Arctic: frequent marine heatwaves. 

The study highlights a stark reality linked to higher anthropogenic greenhouse gas emissions and their profound impact on the Arctic’s marine environment.

Dramatic transformation 

Since 2007, the Arctic Ocean has undergone a dramatic transformation. The researchers found that between 2007 and 2021, the marginal zones of this frigid expanse have been the stage for 11 marine heatwaves, each marking an average temperature increase of 2.2 degrees Celsius above the seasonal norm and lasting an average of 37 days. 

A pattern has emerged since 2015 where marine heatwaves are occurring every year, underscoring a worrying trend of increasing frequency and intensity. 

The role of human activity 

The year 2020 was particularly alarming, witnessing the most severe marine heatwave recorded to date in the Arctic Ocean, which persisted for 103 days, reaching peak temperatures that were four degrees Celsius above the long-term average. 

The results of the analysis indicate that the likelihood of such an event happening in the absence of human-induced greenhouse gas emissions is less than one percent, effectively highlighting the significant role of human activity in these changes.

Accumulation of heat

Dr. Barkhordarian’s study provides critical insights into the mechanisms behind these heatwaves. The research proves, for the first time, that heatwaves are produced when sea ice melts early and rapidly after the winter. This process allows for the accumulation of considerable heat in the water by July, when solar radiation reaches its peak. 

“In 2007, a new phase began in the Arctic,” said Dr. Barkhordarian, who is an expert on climate statistics. “There is less and less of the thicker, several-year-old ice, while the percentage of thin, seasonal ice is consistently increasing.” 

Potential consequences 

The implications of these findings are far-reaching. Marine heatwaves, as defined by the study, occur when temperatures at the water’s surface are higher than 95 percent of the values from the past 30 years for at least five consecutive days.

This new climate in the Arctic not only leads to the continual loss of sea ice but also results in warmer waters, both of which pose substantial threats to the Arctic ecosystem. The potential consequences include the collapse of food chains, reduction in fish stocks, and an overall decline in biodiversity.

Sobering projection 

At the heart of this study is the concept of attribution research, which seeks to delineate the extent of human influence on climate events. By comparing the observed phenomena with models of a world unaffected by anthropogenic greenhouse gases, the research underscores the undeniable impact of human activity on the frequency and severity of marine heatwaves in the Arctic. 

Through the use of satellite data and coupled climate models, the study not only documents the current state of the Arctic Ocean but also provides a sobering projection of its future.

The human factor

“Event attribution analysis demonstrates that the 103-day long 2020 event – the most intense (4 ∘C) recorded so far in the Arctic – would be exceptionally unlikely in the absence of greenhouse gas forcing in terms of both intensity and duration,” wrote the study authors. 

“Our further results imply that if greenhouse gas emissions continue to rise, along with the expansion of first-year ice extent, moderate marine heatwaves in the Arctic will very likely persistently reoccur.”

As marine heatwaves become an annual occurrence in the Arctic, the study highlights the critical importance of understanding and addressing the human contributions to climate change.

Arctic heatwave of 2020

The Arctic heatwave of 2020 was marked by record-breaking temperatures, with a staggering 38°C (100.4°F) recorded in the Siberian town of Verkhoyansk on June 20, 2020. This temperature was confirmed by the World Meteorological Organization (WMO) as a new Arctic record.

The heatwave led to devastating wildfires, significant sea ice loss, and contributed to making 2020 one of the three warmest years on record. The average temperatures over Arctic Siberia reached up to 10°C above normal for much of the summer, emphasizing the rapid warming of the Arctic region.

The study is published in the journal Nature Communications.

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