Can tropical forests cease to be carbon sinks during El Niño?

Yes, tropical forests can stop soaking up carbon dioxide and start releasing it back into the air during strong El Niño events. Think of a rainforest like a giant, leafy sponge that usually soaks up pollution from the sky, but sometimes gets too hot and dry to keep working properly.

Under normal conditions, trees breathe in carbon dioxide CO2 to grow leaves and wood while breathing out oxygen for us to breathe. This makes the forest a carbon sink, meaning it holds more carbon than it lets go. However, El Niño is a weather pattern that warms up the Pacific Ocean, which changes wind patterns worldwide.

When this warming happens, places like Indonesia and the Amazon often get much less rain. Without enough water, the trees get thirsty. To survive, they slow down their growth because making new leaves takes too much energy when water is scarce. It’s like a child who stops playing tag because they are out of breath; the forest slows its eating of carbon.

The bigger problem comes from drought and fire. Dry wood burns easily. When El Niño strikes, farmers and wildfires burn huge areas of forest. Burning is like exhaling sharply. The fire takes the carbon stored in trees and releases it as smoke CO2 all at once.

During a strong El Niño, the forest might release more carbon through fires than it absorbs through photosynthesis. For that year or two, instead of being a helper that cleans the air, the rainforest becomes a contributor to global warming until the rains return and the sponge refills.