Background
The Southern Ocean — one of Earth’s most powerful climate regulators — may be changing faster than previously understood, according to research published May 13, 2026 in the journal Weather and Climate Dynamics. A team led by researchers including Zhaoyang Kong, Andrew T. Prata, Peter T. May, Ariaan Purich, Yi Huang, and Steven T. Siems found that rainfall over Macquarie Island has increased by 28 percent since 1979, driven not by more frequent storms but by storms that are producing heavier rainfall. The findings offer a striking new lens on how the ocean and atmosphere are interacting under accelerating climate stress.
Macquarie Island sits roughly halfway between Tasmania and Antarctica, placing it directly in the path of the Southern Ocean’s storm track. For more than 75 years, the Bureau of Meteorology and the Australian Antarctic Division have maintained continuous weather observations from the island, making it one of the most valuable long-term climate records available for this remote region. Researchers drew on 45 years of daily rainfall data to investigate changes in weather patterns between 1979 and 2023.
Key Developments
The results revealed a transformation with global implications. Annual rainfall on Macquarie Island has risen by approximately 260 millimeters — an increase of 28 percent — since 1979. Crucially, the rise was not a function of more storms arriving over the island. Rather, individual storm systems are delivering more rain when they occur. The Southern Ocean storm track appears to have gradually shifted closer to Antarctica, fundamentally altering the character of the weather systems reaching the island. Meanwhile, a widely used climate reconstruction dataset detected only an 8 percent increase in rainfall — suggesting that satellite-based and computer models are significantly underestimating the change.
The researchers estimate that by 2023, the additional rainfall was adding roughly 2,300 gigatonnes of freshwater per year to the high-latitude Southern Ocean — a volume that exceeds recent contributions from Antarctic meltwater, and the gap is widening. This influx of freshwater alters seawater salinity, which in turn affects how ocean layers mix and how nutrients and carbon cycle through the water. The Southern Ocean is one of Earth’s most important carbon sinks, meaning shifts in its chemistry could influence the pace of atmospheric CO2 accumulation.
The mechanism underlying the change carries its own warning signal. Greater rainfall requires greater evaporation from the ocean surface. Evaporation is one of the primary ways the ocean sheds heat in the cloudy Southern Hemisphere high latitudes — analogous, as the researchers note, to how sweat cools the human body. The team’s calculations suggest the Southern Ocean may now be cooling itself through evaporation 10 to 15 percent more than it did in 1979. In effect, the ocean is “sweating” more as temperatures rise.
Analysis
The implications extend well beyond Macquarie Island. Because the Southern Ocean absorbs a disproportionate share of both the heat trapped by greenhouse gases and the carbon dioxide produced by human activity, changes in its behavior can ripple through the entire global climate system. Altered ocean mixing, shifting current patterns, and disruptions to the carbon cycle are all plausible consequences if the rainfall intensification observed on Macquarie Island is representative of the broader Southern Ocean storm belt.
Scientists caution that Macquarie Island is a single data point in an enormous and sparsely monitored region. Confirming how widespread these changes are represents the next critical step. Still, the 75-year observational record makes this one of the most robust indicators yet that the Southern Ocean’s long-assessed stability may no longer hold.
The study, titled “Intensifying precipitation over the Southern Ocean challenges reanalysis-based climate estimates — Insights from Macquarie Island’s 45-year record,” was published in Weather and Climate Dynamics.
