In recent years, Antarctica has experienced a series of heatwaves that are unparalleled. The continent’s highest-ever recorded temperature was 18.3 °C on February 6, 2020, surpassing the previous record of 17.5 °C, which had been established only a few years prior.
Another intense heatwave in Antarctica in February 2022 resulted in a record-breaking amount of surface ice loss. In March of the same year, East Antarctica experienced its most intense heatwave to date, with temperatures in certain regions exceeding the average by 30°C or 40°C.
We have observed the lowest levels of Antarctic sea ice coverage since the inception of records in the past year.
Temperatures exceeded all previous benchmarks during the heatwave that occurred on February 6, 2020.
It is difficult to avoid the conclusion that recent events that have approached the ludicrous are related to climate change. In reality, research has already been conducted that unequivocally links certain of these heatwaves to global warming. One of our investigations strongly implies that the record-breaking temperatures of 2020 would not have occurred without the influence of climate change.
The changing climate of Antarctica
In 2009, a study quantified the global scope of ecosystem migration as a result of climate change and essentially documented the speed at which specific species must migrate to ensure their survival. The results indicate that the average rate of biome movement over the past decade was 4.2 kilometers per decade, with a range of 0.8 to 12.6 kilometers per decade.
In our most recent study, which was published in February 2024, we modified this speed measurement and applied it to the outer margins of Antarctica. In order to accomplish this, we monitored the southward migration of the zero-degree isotherm.
Boundaries at or below zero degrees are enclosed by the zero-degree isotherm, a fictitious line. The region of Antarctica with temperatures below zero degrees Celsius is becoming increasingly restricted as a result of its southward movement. This movement will have severe repercussions for the cryosphere (areas of the Earth where water is frozen) and ecosystems, as water freezes at zero degrees.
Since 1957, the zero-degree isotherm in the region surrounding the Antarctic has shifted at a rate of 15.8 kilometers per decade, according to our calculations. Conversely, it has shifted at a rate of 23.9 kilometers per decade on the Antarctic peninsula. It has relocated by more than 100 kilometers to the south since the mid-20th century.
These measurements indicate that the rate of climate change along the Antarctic Peninsula is four times greater than the average for all ecosystems.
The temporal progression of the zero-degree isotherm’s annual and seasonal location in Antarctica from 1957 to 2020. The seasons that correspond to each measurement are represented by the initials. MAM is in the fall, JJA is in the winter, SON is in the spring, and DJF is in the summer.
Effects of emission sources
In order to anticipate the consequences of the zero-degree isotherm’s southward migration, twenty distinct climate models were implemented on our data. Despite some variation in its displacement, all models agree that the isotherm will shift significantly further southward in the coming decades.
The isotherm’s trajectory is expected to accelerate in the future decades, irrespective of emissions, as per the models. The extent of its southward migration in the latter half of the twenty-first century will be determined by the amount of carbon that humanity emits.
Assuming that the current emission levels continue, the zero-degree isotherm will continue to advance at a similar pace until the latter half of the 21st century. Conversely, the isotherm will persist in its downward trajectory until the conclusion of the century in the event that emissions are elevated.
Movement in the twenty-first century with regard to the midsummer location of the zero-degree isotherm. According to the IPCC climate scenario SSP5-8.5, current emission levels are expected to have approximately doubled by 2050.
Repercussions on the ecosystem and cryosphere
Not only will the atmosphere be affected by the southward displacement of the zero-degree isotherm, but also the cryosphere (which encompasses all of Antarctica’s polar regions) and the biosphere (which includes the fauna that inhabits the region).
In the most remote regions of the continent, alterations in the isotherm’s position will result in more liquid precipitation than snowfall, despite the potential for an increase in snowfall in other regions.
Accelerated loss of sea ice during summer thaw periods may result from decreased snowfall on the frozen sea, which serves as insulation.
Despite the fact that the precise effects on permafrost, ice shelves, and continental ice are uncertain, the Antarctic Peninsula’s peripheral glaciers will undoubtedly be affected. These are one of the most significant potential contributors to the rise in sea level over the next five decades.
Ecosystems will be affected by changes in the cryosphere. The thawing of ice will render new regions habitable. However, the increased number of areas above zero degrees may allow invasive species from more hospitable, warmer continents to establish a presence, resulting in a competition for resources with native species.
