Special Report

This Is the World's Longest River, for Now

The Nile, the world’s longest river at 4,132 miles, stretches from Central Africa to Egypt, where it empties into the Mediterranean Sea. It is the drainage basin for several of Africa’s largest nations, including the Democratic Republic of the Congo, Kenya, and Ethiopia. It is both a source of fresh water and a means of transportation by boat.

The Nile has two major tributaries. The White Nile, probably the better known of the two, starts at Lake Victoria, which is located in Tanzania, Kenya, and Uganda. The Blue Nile is the other tributary.

Whether the Nile will remain the world’s longest river depends on climate change, which has affected lakes and rivers across the world. The only river that could become longer than the Nile is the Amazon, which is 4,000 miles long. The difference in length between the two rivers is about the same as the distance from New York City to Hartford, Connecticut.

Forecasting the future of the Nile’s length is extremely complex, and any forecast is inconclusive. For example, the world’s oceans are expected to rise because of global warming. The parts of the world this will affect are educated estimates, but are not certain. Some of the largest lakes in the U.S. West have lost substantial amounts of water. This includes the Great Salt Lake, the largest inland salt lake in the United States. It includes the level of the Colorado River, particularly as it approaches the Hoover Dam, and Lake Mead, which supplies water to much of the areas around it. This state has the worst drought in America.

The Nile may not lengthen, but it could be a source of terrible flooding. Monsoons in Ethiopia send massive volumes of water downstream to Egypt. The effective level of this water is expected to drop eventually, however, because of climate change. Here are 25 cities where rising seas could leave millions homeless

According to QZ.com, some projections suggest that:

“the amount of rain in the Upper Nile basin could increase by up to 20%.” However, more recent research also suggests that despite the increased rainfall, “devastating hot and dry spells are projected to become more frequent in the Upper Nile basin,” causing increased water scarcity. (Not Egypt, but this country is least prepared for climate change.)

Additionally, climate events thousands of miles away also are having an effect. The Climate News Network reports how the Nile flow is affected by the cycle in Pacific temperatures. Already in 2015, an intense El Niño year, there was a drought in Egypt. In 2016, La Niña was linked to high flooding. All this suggests that years with normal flow and temperatures will be fewer, with more years of flooding or drought.

What will happen to the length and route of the Nile? The only thing certain is that it will change.

Click here to see the full list of the widest and longest rivers.
Click here to see our detailed findings and methodology.