In 2023, Panama experienced one of the worst droughts in its recorded history, and it severely depleted water available to the Panama Canal, so much that it decreased shipping by 30%. A new study projected that those historic water lows could become the new norm if greenhouse gas emissions continue to rise and the Panama Canal's future depends on action to mitigate emissions.

“If we mitigate emissions and we choose one of the lower emissions pathways, then it really keeps this system pretty stable,” said Samuel Muñoz, lead author of the study and a scientist at Northeastern. “But if we don’t, then these low water levels that are really disruptive now become the norm by the end of the century.”

The canal works by pulling water from freshwater sources such as Gatún Lake, a large man-made lake that also provides drinking water to thousands of residents in nearby Panama City and Colón.

The water is pulled into the canal to raise and lower water levels in locks which allows heavy boats to pass through Panama to move between the Atlantic and Pacific oceans. More than 26 million gallons of water is needed to fill the locks for ships to pass through.

In January 2024, the Woodwell Climate Research Center reported water levels in Gatún Lake, the main lake that feeds the Panama Canal locks, were lower than ever previously recorded. The lake was nearly 2 meters (6 feet) lower than it was just one year prior. This meant Panama Canal Authorities reduced how many ships could move through the canal from 38 to as low as 22 per day and the ship’s cargo needed to be lower in weight.

Muñoz built a model to predict how water levels could change in the next 75 years in different greenhouse gas emissions pathways.

The study was published in Geophysical Research Letters, AGU’s journal for high-impact, short-format reports with immediate implications spanning all Earth and space sciences.

The different scenarios looked at how increased greenhouse gases would change variables like temperature, evaporation, rainfall and other factors that shift with climate change. The scenarios ranged from strong mitigation of greenhouse gas emissions to the current trending levels to extreme and worsening scenarios of emissions.

Read the full article about the Panama Canal's low water levels at AGU.