How Climate Change Is Expanding the Troposphere

By Kylie Wolfe

Climate change is all around us. Maybe you’ve noticed warmer temperatures, excessive droughts, or changing weather patterns. There are plenty of examples in nature, but some aren’t as easy to spot.

Scientists at the University of Toronto found yet another sign of global warming. The troposphere, the layer of the atmosphere closest to Earth’s surface, has expanded by 165 to 200 feet per decade over the last forty years. These findings were published in Science Advances on November 5, 2021.

Layers of the Atmosphere

The Earth’s atmosphere has five distinct layers: troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Each layer has the same composition of gases, but their molecules get farther apart when they’re farther away from Earth. In its entirety, the atmosphere extends from Earth’s surface to 6,200 miles in the sky. It acts as a shield, making the planet livable by keeping it warm, giving us access to oxygen, and preventing excess evaporation.

The layer known as the troposphere holds water vapor and moisture, and it provides the right conditions for cloud formation. It varies in height depending on one’s location; it can be up to 12.4 miles thick above tropical zones and only 4.3 miles near the northern and southern poles.

It’s typical for the troposphere’s upper boundary, known as the tropopause, to rise and fall from season to season. Warmer air temperatures cause it to expand and cooler air temperatures to contract. But what’s been occurring over the last few decades is an accumulation of greenhouse gases.

Some amount of greenhouse gases, such as carbon dioxide, methane, and nitrous oxide, in the atmosphere is natural. Unfortunately, these gases trap heat and, with more of them present due to human activities like driving cars and producing goods, increase warming. That jump in temperature is what’s causing the lower atmosphere to expand.

The Toronto-based research team collected their data using weather balloons. As they ascended, the balloons took numerous measurements to help the scientists reach their conclusion.

A Word of Caution

“We see signs of global warming around us, in retreating glaciers and rising sea levels,” Jane Liu, contributing researcher from the University of Toronto, told Science News for Students. “Now, we see it in the height of the troposphere.”

Even though the troposphere is home to practically all weather, researchers find it unlikely that the changes they see will affect the severity or frequency of the weather we experience. But they caution that it’s yet another example of how climate change is changing our world.