The recent drought in the Panama Canal was not driven by global warming but by below-normal rainfall related to the natural El Niño climate cycle, an international team of scientists concluded.
Low reservoir levels have slowed cargo traffic in the canal for most of the past year. Without enough water to take ships on and off, last summer officials had to reduce the number of vessels they allowed through, creating costly headaches for shipping companies around the world. Only in recent months have crossings begun to increase again.
Water concerns in the area could still deepen in the coming decades, the researchers said in their analysis of the drought. As Panama’s population grows and maritime trade expands, water demand is expected to account for a much larger proportion of available supply by 2050, according to the government. That means future El Niño years could bring even greater disruptions, not only to global shipping, but also to water supplies for local residents.
“Even small changes in rainfall can cause disproportionate impacts,” said Maja Vahlberg, a risk consultant at the Red Cross and Red Crescent Climate Center who contributed to the new analysis, which was published Wednesday.
Panama, in general, is one of the wettest places on Earth. On average, the area around the canal receives more than eight feet of rain a year, almost all of it during the rainy season from May to December. That rain is essential both for the canal’s operations and for the drinking water consumed by approximately half of the country’s 4.5 million inhabitants.
However, rainfall last year was about a quarter below normal, making it the country’s third driest year in nearly a century and a half of records. The drought came shortly after two others that also hampered canal traffic: one in 1997-98 and the other in 2015-16. All three coincided with El Niño conditions.
“We’ve never had a cluster of so many really intense events in such a short time,” said Steven Paton, director of the Physical Monitoring Program at the Smithsonian Tropical Research Institute in Panama. He and the other scientists who conducted the new analysis wanted to know: Was it just bad luck? Or was it related to global warming and therefore a harbinger of things to come?
To answer the question, the researchers looked at both weather records in Panama and computer models that simulate global climate under different conditions.
Scientists found that a lack of rain, and not high temperatures that cause more water to evaporate, was the main reason for the low water level in the canal’s reservoirs. Meteorological records suggest that wet season precipitation in Panama has decreased modestly in recent decades. But the models do not indicate that human-induced climate change is the determining factor.
“We’re not sure what’s causing that slight drought trend, or whether it’s an anomaly or some other factor we haven’t taken into account,” said Clair Barnes, a climate researcher at Imperial College London who worked on the analysis. . “Future trends in a warming climate are also uncertain.”
Scientists found that El Niño, by contrast, is much more clearly linked to below-average rainfall in the area. In any El Niño year, there is a 5 percent chance that precipitation will be as low as in 2023, they estimated.
At the moment, El Niño conditions are weakening, according to the National Oceanic and Atmospheric Administration. La Niña, the opposite phase of the cycle, is expected to appear this summer.
The scientists who analyzed the Panama Canal drought are affiliated with World Weather Attribution, a research initiative that examines extreme weather events soon after they occur. Their findings on the drought have not yet been peer-reviewed.