New study of Earth’s stratosphere has important implications for life on Earth

Understanding how our climate will change in the future, and how the stratosphere is involved, is a monumental challenge. Scientists around the world are grappling with this problem.

A research team led by the University of East Anglia (UEA) just made a major breakthrough. Their research brings new insights about a significant source of uncertainty related to climate change.

How does water vapor in the stratosphere impact Earth’s climate?

For those who don’t know, the stratosphere is a super-dry region of our atmosphere. It’s positioned 15–50 km above the Earth’s surface.

When water vapor increases in this region, climate change may accelerate. This rise in water vapor can also slow down the recovery of the ozone layer, the protective blanket that shields us from the Sun’s harmful ultraviolet rays.

Professor Peer Nowack, who was once part of the Climatic Research Unit at UEA, led this game-changing research. Along with an international team, Nowack developed a new statistical learning method. It combines satellite observations and top-notch climate model data.

The goal? To better understand how much water vapor we can expect in the stratosphere in the future.

How the stratosphere study was conducted

The study, freshly published in the prestigious journal Nature Geoscience, brought out some comforting results. Thankfully, it ruled out the scariest scenarios.

One such terrifying scenario suggested water vapor could go up by more than 25% for every degree of global warming. This new approach brought down the uncertainty by half.

Professor Nowack, currently at the Karlsruhe Institute of Technology, Germany, explained the importance of their study.

He said, “Human-made climate change affects Earth’s atmosphere in many important and often surprising ways. Since water vapor is central to the stratosphere’s physics and chemistry, we needed a new approach to address this longstanding uncertainty factor.”

In his words, the new method “exploits machine learning ideas” and “makes highly effective use of Earth observations to reduce this uncertainty.”

Dr. Sean Davis, a Research Scientist at the National Oceanic and Atmospheric Administration in the U.S., who co-authored the study, supported Nowack’s sentiment.

He said, “With this approach, we were able to show that many climate model projections of very large stratospheric water vapor changes are now inconsistent with observational evidence.”

Climate feedbacks and how they relate to the stratosphere

Understanding stratospheric water vapor trends under global warming has always been a complicated task. It’s even trickier because of climate feedbacks.

Climate feedbacks can either magnify or reduce global warming. They lead to a wide range of possible future temperature increases.

One such feedback involves the amount of water vapor in the stratosphere. While climate models predicted its increase, the extent of the increase was uncertain.

If the stratosphere held too much water vapor due to climate change, it could harm the ozone layer’s recovery. It could also harm the Antarctic ozone hole over this century.

 But Professor Manoj Joshi, a Climate Dynamics professor at UEA and a co-author of the study, brings a sigh of relief.

He said, “Our research implies that while stratospheric water vapour concentrations are likely to increase with global warming, the large changes that could substantially delay ozone recovery are highly unlikely.”

This groundbreaking research was made possible thanks to funding from the UK Natural Environment Research Council through the ML4CLOUDS project. It’s a huge step towards better understanding, predicting, and ultimately combating climate change.

More about the stratosphere

The stratosphere is one of the major layers of Earth’s atmosphere. It’s situated above the troposphere and below the mesosphere. Here are some key details about it:

Location and Thickness

The stratosphere starts roughly around 10 kilometers (about 6 miles) above Earth’s surface at the equator, but at about 8 kilometers (around 5 miles) at the poles. It stretches upwards to about 50 kilometers (31 miles) high.

Temperature Gradient

Unlike the troposphere, where temperature decreases with altitude, the stratosphere sees an increase in temperature with height. This is due to the presence of the ozone layer which absorbs solar ultraviolet radiation, converting it into heat.

Ozone Layer

The stratosphere contains the ozone layer, which is about 20 to 30 kilometers (12 to 19 miles) above the Earth’s surface. The ozone layer plays a crucial role in absorbing most of the Sun’s harmful ultraviolet radiation, which can cause skin cancer and cataracts, harm ecosystems, and damage certain types of plastics.

Weather and Clouds

The stratosphere is generally stable and calm with few weather disturbances, unlike the turbulent troposphere below it. This is because the temperature increases with altitude in the stratosphere, reducing the amount of convection, or upward air movement.

There are, however, some cloud types that can form in the stratosphere under specific conditions, like nacreous (mother-of-pearl) and noctilucent clouds.

Air Traffic

The stratosphere’s stability is one reason it’s used for commercial jet flight. The lack of weather disturbances and turbulence makes for smoother flights.

Life

The stratosphere isn’t very hospitable to life as we know it, due to the low temperatures, low pressure, and intense solar radiation. However, some resilient bacteria and spores can survive there.

Stratospheric Cooling

While global warming heats up the Earth’s surface and the troposphere, it’s causing the stratosphere to cool. This is because increased levels of greenhouse gases in the troposphere trap more heat, leaving less to reach the stratosphere.

Stratospheric Water Vapor

Changes in the amount of water vapor in the stratosphere can affect the climate. More water vapor can trap more heat, leading to surface warming. It can also impact the ozone layer’s chemistry.

Remember, our understanding of the stratosphere and other atmospheric layers continues to evolve as we develop more advanced observational technologies and models.