Why climate change poses an existential threat to Panama Canal

Sub: IR

Sec: Places in news

Context:

The first ship passed through the Panama Canal on August 15, 1914, exactly 110 years ago.
Now, the Panama Canal is facing existential threat due to climate change.

About Panama Canal:

The 82-km long artificial waterway connects the Atlantic and Pacific Oceans through the Isthmus of Panama.
It remains one of the greatest feats of engineering in history
It saves approximately 12,600 km in a trip between New York and San Francisco, and is one of the most important shipping lanes in the world.

Why does the canal face an existential threat?

The canal operates on a system of locks and artificial lakes, particularly Lake Gatun that provides water needed to operate the locks.
However, there has been a trend of drop in the water levels of Lake Gatun due to droughts.
Low water level in Lake Gatun is affecting the canal’s capability to handle ships.

System of water elevators

The Panama Canal is a sophisticated, highly-engineered system which uses a series of locks and elevators to take ships from one end to the other.
This is needed because the two oceans that the Panama Canal connects lie at different elevations, with the Pacific slightly higher than the Atlantic.
This difference means that for a ship entering the canal through the Atlantic, it needs to gain elevation during its journey to the Pacific. This is achieved using a lock system which lifts and drops vessels to the required sea level at either end of the canal.

How a set of locks works:

A ship approaches the first, lowest chamber of a lock, which lies at sea level;
The locked gate opens to allow the ship into the chamber, and closes behind it;
The valve between the first and second chamber (at a higher elevation) is opened to increase the water level of the first chamber;
The gate between the two chambers is opened once the water level is equalised, and the ship enters the next chamber.
This process is repeated to gain elevation.
The reverse process occurs when lowering ships back to sea level.

Threat of climate change:

The Panama Canal needs massive amounts of fresh water to facilitate the passage of ships using this system of locks. Most of this water is supplied from Lake Gatun.
According to a report by New York Times, the passage of a single ship needs more than 50 million gallons (almost 200 million litres) of water.
Last year, lower water levels in Lake Gatun meant that far fewer ships could pass through the canal every day.

A contentious solution

The solution proposed by the Panama Canal authorities is to create a second source of water for the canal by creating a dam on the Rio Indio.
This could potentially secure water availability for the next 50 years, but has sparked controversy due to displacement issues.