Is It Unstoppable? The Tipping Point of Antarctica and Humanity's Choices - The Staircase Collapse Beyond "1.5°C"

3. "Regime Shift" in Sea Ice and the Slowdown of the Ocean's "Blood Flow"

In recent years, Antarctic sea ice has repeatedly recorded extremely low levels, even by historical standards, described as a **"regime shift beyond the range of natural variability."** The decrease in sea ice lowers the albedo, further warming the ocean and promoting the slowdown of Antarctic overturn circulation. When circulation weakens, nutrients are less likely to upwell to the surface, reducing carbon absorption and ecosystem productivity, with negative impacts spreading from organisms to the climate. dx.doi.org

4. Penguins and Krill—Ecosystems Losing Their "Footing" and "Sustenance"

The early breakup of sea ice has caused breeding failures of emperor penguins in various regions. Satellite image analysis has confirmed years when chicks were almost entirely wiped out across regions. There are also concerns about significant declines in krill and some penguin and seal species, as well as the weakening of the phytoplankton base. The crisis facing living organisms also affects fishery resources and carbon cycles. ScienceDaily

5. The Collapse of the "Ice Gate" Progressing Simultaneously

On November 6, news also emerged about the latest research tracking how the ice shelf of the Thwaites Glacier (known as the "last bastion of Earth") has been damaged and disintegrated over the past 20 years. The ice shelf acts as a "gatekeeper" for ice sheet outflow. When it becomes more prone to breaking, the inland ice's slide accelerates. It was a day when the news aligned with the overall picture painted by the review. UM Today

6. Reactions on Social Media: Researchers' Sense of Crisis, Institutional Awareness, and Distance from "Doomers"

On X (formerly Twitter), polar researchers and institutional accounts summarized the points of the review, spreading the terms "sea ice regime shift," "WAIS criticality," and "ocean circulation slowdown". For example, WCRP's climate and cryosphere program and Antarctic researchers' accounts explained the "mutually amplifying abrupt changes" with accompanying charts from the paper. In contrast, there were a few skeptical mentions like "the critical point is exaggerated" or "it's still uncertain." On bulletin boards, Reddit's climate-related threads saw discussions grow about the chain reaction of sea ice and ocean currents and implications for coastal cities. In the comment sections of scientific media, some pointed out the uncertainty of expressions like "could/may." Meanwhile, Australian media and Reuters reported that "the decline in sea ice is a 'sign of criticality,'" emphasizing that researchers themselves stress **"criticality may be exceeded even in the best case." While there is a risk of the discussion leaning towards "doom" (doomer), the climate research community maintains a stance of simultaneously conveying " the room to avoid the worst and concrete adaptation measures." X (formerly Twitter)

7. "So What Will We Change?"—Translation into Practice

(1) Japan's Coastal and Urban Infrastructure
Long-term sea level rise is inevitable. There is a need to reevaluate levee heights, design for compound hazards of storm surges and uprisings, and build redundancy in coastal supply chains (ports, warehouses, power generation, IT hubs). Check against the worst-case scenario of **"gradual acceleration this century"** and proceed in tandem with land use regulations and relocation plans. dx.doi.org

(2) Industry, Finance, and Insurance
Ice sheet risk is a "fat-tailed risk." Within decades, there could be a reorganization of insurance premium rates and port relocations in international supply chains. It is essential to disclose and allocate capital for not only the "transition" but also the "physical"** risks in climate-related financial disclosures (TCFD/ISSB). dx.doi.org