Global Warming

World's Largest River Floods Five Times More Often Than It Used to

Extreme floods have become more frequent in the Amazon Basin in just the last two to three decades, according to a new study.

After analyzing 113 years of Amazon River levels in Port of Manaus, Brazil, researchers found that severe floods happened roughly every 20 years in the first part of the 20th century. Now, extreme flooding of the world's largest river occurs every four years on average—or about five times more frequently than it used to.

This increase in flooding could be disastrous for communities in Brazil, Peru and other Amazonian nations, the researchers pointed out. There are catastrophic effects on the lives of the people as the drinking water gets flooded, and the houses get completely destroyed.

This dramatic increase in floods is caused by changes in the surrounding seas, particularly the Pacific and Atlantic oceans and how they interact. Due to a strong warming of the Atlantic Ocean and cooling of the Pacific over the same period, we see changes in the so-called Walker circulation, which affects Amazon precipitation. The effect is more or less the opposite of what happens during an El Niño event. Instead of causing drought, it results in more convection and heavy rainfall in the central and northern parts of the Amazon basin.

With temperatures in the Atlantic expected to continue warming, the scientists expect to see more of these high water levels in the Amazon River.