The Panama Canal requires a colossal amount of water to operate. A study warns that climate change could threaten this.

The 2023 drought caused water levels to drop so low that restrictions on the number of ships allowed through were imposed. (Image credit: Walter Hurtado/Bloomberg via Getty Images)

The Panama Canal, a vital route for global maritime trade, could be threatened by reduced rainfall and increased evaporation due to climate change unless greenhouse gas emissions are reduced, according to a new study.

Gatun Lake provides the vast amount of freshwater needed to operate the canal's locks. However, researchers have found that under a high-emissions scenario, in which greenhouse gas levels continue to rise, the water level in Gatun Lake will decline significantly over the next 75 years.

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Scientists have calculated that the risk of drought in Lake Gatun will increase significantly by the end of the 21st century unless greenhouse gas emissions are reduced.

The team used average water level measurements and precipitation data from 1965 to 2023, as well as precipitation and evaporation estimates, to create models of future lake water levels. They then used this model to generate water level projections under various climate change scenarios.

The researchers found that under low-emissions scenarios, lake water levels remained relatively stable. However, under higher-emissions scenarios, low water levels became increasingly common throughout the 21st century. Under the highest-emissions scenario, the probability of reaching 2016 levels or lower in any given year doubled by the end of the 21st century, increasing from 2.5% to 5%.

“For Panama, this means, at least what the models tell us, that rainfall, especially during the rainy season, is decreasing,” Muñoz said.

The results indicate that the primary cause of the rainfall reduction is rising temperatures in the Pacific Ocean. The study is complicated by the fact that warming in the Pacific Ocean is also characteristic of years with strong El Niño events, which correlates with the rainfall deficit in Panama. It is currently unclear what impact climate change will have on future El Niño events and the broader El Niño-Southern Oscillation cycle, and potential changes to this system were not included in the study.

“The model isn't perfect. It's just a simulation. It's the best we can do right now,” Munoz said.

Steve Peyton, director of the Smithsonian Tropical Research Institute's (STRI) Physical Monitoring Unit in Panama, has been monitoring weather conditions on the Isthmus of Panama for nearly 30 years. Peyton, who was not involved in the study, urged caution in interpreting its findings, noting that the decade-to-decade variability of Panama's weather makes it difficult to detect the effects of climate change.

“It would be very, very difficult to pull something out and say it's a signal of climate change,” he told Live Science.