Climate change inflicts damage in numerous ways, giving rise to hurricanes, heat waves, floods, droughts, and wildfires. A new study published in *Scientific Reports* now adds earthquakes, continental rifting (or breakup), and magma production to that list. This research contributes to a growing scientific consensus that the Earth’s atmospheric processes can unexpectedly influence its geological processes.

Geologist James Muirhead, a senior lecturer at the University of Auckland in New Zealand and the paper’s lead author, stated, “Ultimately, plate tectonic forces are the primary drivers of continental rifting. However, our study demonstrates that climate plays a crucial role in regulating the speed of continental rifting, which can instigate periods of heightened earthquake or volcanic activity.”

Muirhead and his colleagues based their conclusions on studies of Lake Turkana, a body of water spanning 155 miles in length and 18 miles in width, situated in Northern Kenya. This part of the country lies within the East African Rift Valley, a region characterized by numerous deep lakes and tectonic fractures. The researchers collected seismic data from 27 faults beneath Turkana, examining activity over the past 10,000 years—a timeframe that witnessed significant changes in East Africa.

From approximately 9,600 years ago to 5,300 years ago, the continent experienced climatic conditions known as the African Humid Period. Subsequently, from 5,300 years ago to the present, the post-African Humid Period prevailed. As their names suggest, the former interval was marked by a warm, wet continent with abundant rainfall and flooding; the latter saw drier conditions and some desertification. The local lakes underwent corresponding transformations.

Chris Scholz, a professor of Earth sciences and a co-author of the study, remarked in an accompanying statement, “Water levels in Lake Turkana reflect the regional ‘hydroclimate.’” He added, “During wetter intervals, roughly 9,600 to 5,300 years ago, the lake’s surface was hundreds of feet higher than it is today.”

This, in turn, affected the ground beneath the lakes. Water is heavy, weighing considerably—a factor that quickly accumulates in a lake the size of Turkana. All this water weight exerts a constant downward pressure, suppressing rifting and magma flow, thereby keeping the subterranean region relatively stable. This occurs when the lake is full. However, as temperatures rise and rainfall diminishes, water levels can drop by as much as 450 feet over one or a few centuries, significantly easing that pressure—and allowing the earth to become active.

“We observed that faults slipped more rapidly and more magma was produced…when the lake levels were lower,” Scholz explained. Such increased activity beneath other lakes that also experienced drying could have contributed to the subterranean fracturing characteristic of the entire East African Rift Valley.

Africa is far from the only place where this phenomenon would have transpired. Muirhead, Scholz, and their colleagues point to similar patterns of rising and falling water levels leading to decreasing and increasing seismic activity in Iceland and the Yellowstone region of the western U.S. The melting of the ice cover that blanketed much of the planet’s northern latitudes at the end of the last Ice Age could have similarly unleashed powerful tectonic forces.

Muirhead stated, “A number of studies have shown that the retreat of glaciers…led to heightened activity along fault lines in North America and Europe.” He continued, “Similarly, magma production at Earth’s mid-ocean ridges has been hypothesized to change in response to fluctuating sea levels during glacial and inter-glacial periods on Earth.”

Unlike most geological processes, which unfold over millions of years, changes in water levels occur relatively quickly. “Lake level drops of this magnitude can happen over hundreds of years, and the stress changes associated with a reduction in lake water loading would have been perceived almost immediately by fault lines across Lake Turkana, increasing the likelihood of faulting,” Muirhead said. “The magmatic system would likely have taken a little longer to respond to this pressure reduction, on the order of thousands of years.”

In the short term, this might not pose an issue—at least concerning Lake Turkana. The researchers cite climate models predicting increased rainfall across the region over the next two decades. While this may cause localized flooding—which can lead to its own form of devastation—it will also replenish the lake, augmenting its water volume and helping to contain tectonic forces.

Moreover, these impacts will not manifest with every rainfall or season, but rather cumulatively over decades or centuries. Nevertheless, these are relatively short timescales when considering planetary dynamics, and this has implications for policymakers, developers, and insurers, who will need to factor seismic activity into their long-term planning.

Muirhead concluded, “If I were conducting a hazard assessment for a fault line in a continental rift like Turkana, I would need to consider how its rate of activity, and the resulting likelihood of an earthquake, is affected by the current climate state and associated lake water volumes.”