New Zealand’s breathtaking Ruataniwha Conservation Park has become an open-air research laboratory for US scientists gathering evidence on the Zealandia Switch, its connection to climate change, and why it disrupts the well-established theory of a Serbian mathematician and astronomer.
University of Maine graduate students Tricia Collins and Alexzander Roman and several other earth science experts are studying large rocks deposited here by glaciers during the Last Glacial Period.
The boulders hold crucial insights into abrupt climate change in the past and its implications for the future as the Earth warms rapidly.
The part Collins and Roman are working on will help piece together the atmospheric, oceanic, and planetary forces that trigger ice ages. Their work, much of which has been conducted under very harsh conditions, will help assemble a better understanding of how these forces play out today.
Associate Professor Aaron Putnam (University of Maine), his students and renowned geologist George Denton, think they’ve cracked the code to ice age triggers—a problem that has puzzled scientists since the 19th century.
Essentially, their work contests the conclusions of early 20th-century mathematician and astronomer Milutin Milanković, whose theory on ice ages centred around orbital cycles affecting insolation has long been accepted.

Researchers like Denton, Putnam, and their team propose the Zealandia Switch hypothesis.
This theory suggests that ‘orbital forcing’ primarily impacts the Southern Hemisphere, particularly the position of the austral westerlies, thus influencing global climate change events.
By looking at how the westerlies shift, researchers can explain the mechanisms behind ice ages on a global scale.
The Zealandia Switch hypothesis challenges traditional views, suggesting that Milanković may have focused on the wrong hemisphere.
Climate modelling by Joellen Russell (University of Arizona) and others supports this hypothesis, showing how the westerlies’ positions impact oceanic and atmospheric circulation, affecting global temperatures.
The switch mechanism, which toggles between two modes based on the westerlies, can shed light on abrupt climate change events such as the end of an ice age.
This research expands our understanding of past climate dynamics and has implications for current climate models. With the planet experiencing unprecedented warming, insights from these studies may help update predictive models to better anticipate future climate scenarios.
The Zealandia Switch hypothesis could provide a more comprehensive explanation of how abrupt climate change occurs and its potential impacts in a rapidly changing world.
NOTE: The above piece briefly summarises the original article published on the Bulletin of the Atomic Scientists website. Check it out. It’s well worth the read!