As plummeting water levels in the Panama Canal cause a maritime traffic jam, authorities have declared that restrictions on the passage of ships will endure for one year unless rainfall surges.

“In a summer that has seen record temperatures and forest fires across chunks of the Northern Hemisphere, the drying canal is another reminder of the extent to which a warming planet is likely to upend global trade,” reports Bloomberg.

A vital shortcut between the Atlantic and Pacific oceans, the canal handles more than half a billion tonnes of cargo annually, or 6% of the world’s maritime commerce. It is key to moving automobiles, other manufactured goods, crops, and oil and gas products across the globe.

Panama is usually considered among the world’s wettest countries. But as high-pressure heat domes reduce rainfall and deliver intense heat, the canal region is experiencing one of its driest seasons since record-keeping began 143 years ago.

“Normally, there are up to 90 ships waiting to enter the canal,” the Washington Post wrote August 24. “This week, there were more than 120. Earlier this month, as many as 160 ships sat idling.”

To move through the locks (water elevators) in the canal, each ship needs 200 million litres of water, which is provided by two artificial lakes fed by rainfall in the surrounding watershed. A combination of a developing and powerful El Niño, warming waters in the equatorial Pacific Ocean, and human-caused climate change have led to a scarcity of water and greater levels of evaporation this year, writes the Post. That means fewer ships can pass, and those that enter the canal need to offload cargo and lose precious time to sit higher in the water.

Ships have to reserve a spot in advance, or buy one through an auction process. But with current restrictions in place, wait times have increased from between three and five days to around 11 days, at times even reaching 19 days. Canal operators estimate the restrictions will likely reduce earnings by $200 million in 2024 compared to this year, reports Agence France-Presse.

Some companies are trying to avoid delays by taking alternate routes, or deploying other strategies like unloading cargo for overland transport. Canal operators say that, unless heavy rains fall in the next three months, access restrictions will stay in place for up to one year to give clients “a year to plan” how to adapt.

The impact on the shipping industry is adding another layer to the turmoil caused by the COVID-19 pandemic and Russia’s invasion of Ukraine, said Abe Eshkenazi, CEO of the Chicago-based Association for Supply Chain Management.

“We’re seeing just another disruption on top of an already stressed system.”