Antarctica at brink of irreversible climate change

At COP30 in Brazil, Australian scientists have raised alarms about the rapid and irreversible climate changes now unfolding in Antarctica. These changes come as global temperatures exceed the 1.5°C threshold outlined by the Paris Agreement, marking a critical point for the planet’s future climate stability.

The new research highlights a range of alarming shifts across the Antarctic region, including the rapid decline of sea ice, weakening ocean currents, destabilizing ice sheets, and drastic transformations in ecosystems. Experts warn that these changes are likely to have far-reaching consequences for coastal regions and global weather patterns, Earth.com writes.

According to the research, the Antarctic region is experiencing what scientists call "abrupt change"—a term used to describe climate shifts that occur much faster than expected. These rapid transitions are potentially locked into place for generations. Prof. Nerilie Abram, a paleoclimate scientist from the Australian Antarctic Division, led the study, which analysed climate records from ice cores, ocean data, and ecosystems across the continent.

"We argue that decisions taken in this decade will strongly influence whether those changes remain limited or accelerate into effectively irreversible states," said Prof. Abram.

One of the most alarming trends is the dramatic reduction in Antarctic sea ice, which has fallen to record lows in recent years. While sea ice had been relatively stable for decades, recent satellite data since 2016 indicates unprecedented declines. This dramatic shift is driven by a combination of warming subsurface oceans and changing wind patterns, forcing the region into a new low sea ice state.

Scientists predict that this trend will continue for decades, even if global temperatures stabilise.

"Because the ocean stores so much heat, Antarctic sea ice is expected to keep declining for many decades," Prof. Abram said.

In addition to sea ice loss, deep ocean currents are also showing signs of weakening. The Antarctic Overturning Circulation, a crucial global climate pattern that drives the movement of cold, salty water around the globe, is expected to slow by up to 40% by 2050—double the pace seen in the North Atlantic. This slowdown will reduce the supply of oxygen-rich water to marine ecosystems and disrupt nutrient cycles that sustain marine life.

The melting of Antarctica's ice sheets is another area of concern. The West Antarctic Ice Sheet, which sits on bedrock below sea level, is particularly vulnerable to ocean-driven retreat. Once this process passes certain "tipping points," the flow of ice into the ocean is likely to continue for centuries, even if temperatures stabilise.

Simulations suggest that high emissions could lead to a 3-metre rise in sea levels, with more changes "committed" for millennia. Even if emissions are reduced, future generations will still have to deal with rising seas long after the current century ends.

Antarctica’s ecosystems are also undergoing abrupt transformations. Some land areas are becoming greener, with moss-dominated ecosystems expanding rapidly, while other regions are drying out, damaging long-lived moss beds. Marine ecosystems are also being affected as ice conditions shift. For example, algae-dominated communities are replacing filter-feeding organisms on the seafloor near retreating ice shelves.

The fate of iconic Antarctic species, such as the emperor penguin, is also under threat. These penguins rely on stable, land-fast sea ice for breeding and survival. However, in recent years, some colonies in the Bellingshausen Sea suffered breeding failures as sea ice broke up too early in the season.

"Long-term modeling indicates that continued warming and sea ice decline could cut global emperor penguin numbers by more than half," said Prof. Abram. "Field biologists now worry that frequent regional breeding failures will push some colonies beyond recovery."

The changes happening in Antarctica will not be confined to the region. The loss of sea ice and the weakening of deep ocean currents will have significant global consequences. As the ice melts, dark ocean waters are exposed, which absorb more sunlight and accelerate regional warming. This process could intensify storms in the Southern Hemisphere.

Additionally, the weakening Antarctic overturning circulation is expected to alter heat transport between the hemispheres, impacting rainfall patterns and increasing climate variability in many parts of the world. The long-term rise in sea levels due to Antarctic ice loss will reshape coastlines, threaten coastal infrastructure, and put immense pressure on adaptation strategies worldwide.

Prof. Abram emphasised that urgent action is needed to limit the damage.

"The surest way to avoid triggering multiple irreversible Antarctic changes is to cut greenhouse gas emissions deeply this decade," she said. "Emission cuts and ecosystem protections must occur together, since reducing local pollution, fishing, and invasive species can preserve remaining resilience."

By Sabina Mammadli