1,1,4,1,3- 1School of Systems Science / Institute of Nonequilibrium Systems, Beijing Normal University, Beijing, China
- 2Department of Earth System Science, Tsinghua University, Beijing, China
- 3Institute for Advanced Study in Physics and School of Physics, Zhejiang University, Hangzhou, China
- 4Potsdam Institute for Climate Impact Research, Potsdam, Germany
The polar regions are critical components of complex Earth systems, housing potential tipping elements such as the West Antarctic Ice Sheet and sea ice systems. However, the climate trajectories of the two poles have diverged significantly over the past century. While the Arctic has exhibited rapid warming and dramatic sea ice loss—a phenomenon known as Arctic amplification—the Antarctic has shown a delayed and more heterogeneous response. Observations indicate that prior to the late 1980s, parts of Antarctica experienced warming and moistening while the Arctic remained relatively stable; subsequently, this pattern reversed, with the Arctic undergoing accelerated change while the Antarctic trend slowed or displayed spatial variability. Understanding the drivers of polar climate variability is paramount for anticipating potential abrupt transitions or tipping points in the regions.
Here, we identify a robust internal variability mode in atmospheric water vapor—termed the Interdecadal Bipolar Oscillation (IBO)—that provides a physical explanation for these historical asymmetries. Using the eigen microstate theory on ERA5 reanalysis and CMIP6 simulations (historical, piControl, and SSPs), we reveal that the IBO links the Arctic and Antarctic in a quasi-periodic (60–80 years) seesaw pattern. We demonstrate that the IBO has modulated interdecadal asymmetries in polar climate change over the past 80 years. Specifically, a phase shift in the late 1980s accelerated Arctic moistening while suppressing similar changes in the Antarctic.
Crucially, our projections under various Shared Socioeconomic Pathways (SSPs) indicate an imminent IBO phase reversal in the coming decades. This transition is expected to shift the IBO from a dampening to an amplifying phase for the Antarctic, coinciding with the background global warming signal. We suggest that this alignment could trigger a regime shift toward rapid Antarctic moistening and warming, potentially destabilizing the ice sheet–atmosphere interactions. The IBO thus acts as a critical internal regulator that may modulate the distance to tipping points in the polar climate system. By elucidating the interplay between this internal oscillation and external anthropogenic forcing, our study offers new insights into the mechanisms that could precipitate abrupt climate transitions in the Antarctic.
How to cite: Wang, H., Fan, J., Xie, F., Li, J., Shi, R., Xia, Y., Chen, D., and Chen, X.: The Interdecadal Bipolar Oscillation: A Potential Driver for Rapid Antarctic Climate Transitions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7606, https://doi.org/10.5194/egusphere-egu26-7606, 2026.
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An important topic as it can affect many people. It's good you caught that pattern. Too much polar melting freshens ocean water, making colder climate (fresh water freezes more quickly than salt water) and then there can develop albedo and thus reflection rather than absorption of the sun's light & heat, and then, more cold. Consider this possibility for the 60-80 year periodicity (and I truly don't know whether it applies, but the numbers matched), that there is a solar cycle called the Gleissberg cycle, and it is every 66 years, which falls in the range you indicated, and it refers to six times of the 11-year short solar cycle in which the sun's magnetic poles reverse, and there are certain things that happen regularly every 66 years. It's just an idea. But the topic is important, as it can affect habitability for many human habitats.
Apologies for the delayed reply. Thank you very much for your positive feedback and for suggesting this interesting possible connection.
We agree that the physical origin of the IBO is an important question, and this is something we have also been considering carefully. After reviewing the Gleissberg cycle, it is generally considered a broad low-frequency variation in solar activity with a typical timescale of about 80–100 years. The maximum appears to occur around the mid-20th century, while the major phase transition of the IBO in our results occurs around the late 1980s in the polar water vapor system. The direct connection does not appear straightforward in terms of both periodicity and phase.
Moreover, IBO-like variability is also found in CMIP6 pre-industrial control simulations under, which suggests that the IBO can arise as an internal mode of climate variability. Still, we agree that solar variability could potentially modulate the amplitude or phase of such internal modes, and this is an interesting direction for future study.
Thank you again for this thoughtful suggestion.
Apologies for the delayed reply. Thank you very much for your positive feedback and for suggesting this interesting possible connection.
We agree that the physical origin of the IBO is an important question, and this is something we have also been considering carefully. After reviewing the Gleissberg cycle, it is generally considered a broad low-frequency variation in solar activity with a typical timescale of about 80–100 years. The maximum appears to occur around the mid-20th century, while the major phase transition of the IBO in our results occurs around the late 1980s in the polar water vapor system. The direct connection does not appear straightforward in terms of both periodicity and phase.
Moreover, IBO-like variability is also found in CMIP6 pre-industrial control simulations under, which suggests that the IBO can arise as an internal mode of climate variability. Still, we agree that solar variability could potentially modulate the amplitude or phase of such internal modes, and this is an interesting direction for future study.
Thank you again for this thoughtful suggestion.