Canberra, Aug 21 (The Conversation) - Once considered a remote and unchanging wilderness, Antarctica is now facing rapidly accelerating environmental changes. The ice-covered continent, along with the surrounding Southern Ocean, is undergoing significant transformations. Sea ice is disappearing swiftly, ice shelves are melting at an increased rate, and the ice sheets that blanket the continent are approaching dangerous tipping points. Crucial ocean currents are also showing signs of slowing down.
Published today in Nature, new research highlights that these abrupt shifts are not only happening but are expected to intensify significantly in the future. Fieldwork on the ice has enabled several authors of this study to witness these unsettling changes firsthand.
The implications for wildlife, from iconic species to those less recognized, are concerning. Moreover, the changes are set to impact the world for generations. Rising sea levels and extreme climate alterations will be felt globally.
Defining abrupt change, scientists describe it as a climatic or environmental shift that occurs much faster than anticipated. Such changes are particularly worrisome because they have the potential to amplify themselves. For instance, when sea ice melts, the oceans warm more rapidly, which then leads to even more ice melting. Once triggered, these changes can prove difficult or even impossible to reverse within timeframes relevant to human life.
Contrary to the assumption that incremental warming leads to gradual change, Antarctica shows a divergent pattern. Over recent decades, the Antarctic environment exhibited a subtler response to human-induced climate warming when compared to the Arctic. Yet, around a decade ago, abrupt changes began emerging.
Sea ice around Antarctica has been decreasing drastically since 2014. The decline rate is now double that of the Arctic sea ice. Research indicates that these unfolding changes are unprecedented, far beyond what has been historically observed.
The consequences are wide-ranging. Sea ice, with its reflective, high-albedo surface, reflects heat back into space. With less sea ice, darker ocean waters absorb more heat. This shift poses real threats to species like the emperor penguins, which rely on the ice for habitat and breeding. Fewer ice formations leave Antarctica’s ice shelves more vulnerable to wave exposure.
The melting ice is slowing down the deep ocean circulation around Antarctica. Known as the Antarctic Overturning Circulation, this crucial current system plays a vital role in regulating Earth’s climate by absorbing carbon dioxide and distributing heat.
Similar concerns exist for the Atlantic Meridional Overturning Circulation in the northern hemisphere. Observations now suggest a comparable risk in the Southern Ocean currents, potentially changing at twice the rate of its more famous North Atlantic counterpart.
A slowdown could hamper the ocean's ability to absorb oxygen and carbon dioxide, leaving critical nutrients at the seafloor. A decline in oxygen and nutrient availability would severely impact marine ecosystems and disrupt climate regulation.
Alarmingly, the West Antarctic Ice Sheet and certain regions of East Antarctica are now shedding ice and contributing to sea level rise. Ice loss has increased sixfold since the 1990s.
The West Antarctic Ice Sheet alone has the potential to elevate global sea levels by over five meters. Scientists caution we might be nearing the point where this ice sheet risks collapsing even without further substantial warming—a process that could span centuries to millennia.
These massive ice sheets represent a global tipping point risk. They introduce the greatest uncertainty in projecting future sea level rise because the speed of potential collapse is unknown.
Globally, at least 750 million individuals reside in low-lying coastal zones. Rising sea levels threaten infrastructure and settlements along the coast worldwide.
The biological systems of Antarctica are also experiencing abrupt transformations. Both marine and terrestrial ecosystems are being reshaped by warming temperatures, unstable ice conditions, and human activities, including pollution and the introduction of invasive species.
Protecting these ecosystems through the Antarctic Treaty is essential. This involves establishing protected areas on land and sea and restricting specific human activities. However, these conservation efforts alone won't suffice to ensure the survival of species like the emperor penguin and the leopard seal. Decisive global action to curb greenhouse gas emissions is crucial.
Historically seen as a symbol of isolation and permanence, Antarctica is now undergoing concerning rapid changes far beyond scientists’ initial expectations. These shifts predominantly result from the excess heat trapped by unchecked greenhouse gas emissions over decades.
The only way to prevent further abrupt changes is to significantly cut emissions, aiming to keep warming as close to 1.5°C as feasible.
Even with these efforts, much change is already underway. Governments, businesses, and coastal communities must brace for a future characterized by abrupt shifts. What transpires in Antarctica will have far-reaching effects beyond its icy boundaries.
The stakes are extremely high. The decisions made today will shape whether we confront a future with worsening impacts and irreversible changes or a future where we can adapt to the changes already set in motion. (The Conversation)
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