INQUIRING MINDS

The Key is in the Clouds

By Kenneth Mashinchi

To fully understand the ramifications of climate change, SJSU Professor Minghui Diao says we have to look first to the clouds.

It may only take a second to breathe, but that breath lasts more than a lifetime in the air. San José State University Associate Professor of Meteorology and Climate Science Minghui Diao says the carbon dioxide we exhale can linger in the air for anywhere from 100 to 300 years.

Now add emissions from cars, factories and other CO2 producers, as well as potential long-lasting damage the atmosphere is still being exposed to from as far back as the 1700s. Diao’s research on clouds and aerosols, like our breath, proves vital in understanding the cascading effect the air has on global warming.

“If we want to hold a crystal ball to our future, if we want to know what's gonna happen to our children and children's children, what will happen in the next 50, 100 or 200 years? Are we going to see all the arctic ice disappearing? Are we going to see more and more wildfires? We want to predict that,” says Diao, who joined SJSU in 2015. “But what is stopping us from getting an accurate prediction right now are clouds and aerosols.”

Diao says water vapor is the most powerful greenhouse gas, and because our world is warming up, water from the oceans is evaporating and producing clouds. But those clouds don’t necessarily produce rain or snow, hence why weather reports are more prediction than fact. Diao says this uncertainty of clouds makes it unclear how they will affect temperatures in the future.

“If we want to hold a crystal ball to our future, if we want to know what's gonna happen to our children and children's children, what will happen in the next 50, 100 or 200 years?"

— Minghui Diao

“People look at the sky, and they think about clouds as these harmless, very beautiful artistic features,” says Diao. “But they hold the key, which can be either good or bad.

“Some days you see these very dark, low-hanging clouds — in terms of blocking the sun, they are like a sun umbrella that reflects more sun back, so we're getting less energy from it. Also, there are these flimsy, high clouds. They actually trap the solar energy coming to the Earth and act more like a blanket to reinforce the greenhouse effect. So clouds can either minimize or make the greenhouse effect even worse.

Obtaining data from clouds happens in two ways: aircraft observation, where a plane fitted with data instruments on the inside and outside flies directly through the cloud, and satellite or ground-based remote sensing, which requires sending out a signal and seeing what data comes back after interacting with the clouds.

Diao has flown around the world to gather samples of clouds, with field campaigns taking her from the North Pole to Antarctica. She says researchers will also fly above the clouds of a hurricane and drop instruments into the eye of the storm to gather information like humidity and temperature.

Diao and her students are currently creating model simulations of clouds to better predict the future climate, while also observing how certain aerosols, like dust or airplane emissions, affect the high clouds in our atmosphere.

So next time you’re outside, consider observing the clouds above you and know they hold the key to our future climate.

Want to learn more?

Visit the SJSU Cloud and Aerosol research group

Top photo: Robert C. Bain. Illustration by Jennifer Guo, '24 Animation/Illustration.