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Yusuf Hamied Department of Chemistry

Print stands on the department rooftop in front of the iconic Cambridge blue chimmneys.

Up in the air

Print is a third-year PhD student in atmospheric sciences studying the effects of toxic sulphur dioxide emissions over two highly affected areas: Europe and Eastern Asia.

Aerosols formed from sulphur dioxide are responsible for cooling the planet; however, the precise amount has a large margin of uncertainty. Print is working in the Archibald group to reduce these error bars so that the effects of releasing sulphur dioxide gas can be accurately understood.

“It’s very important to have accurate models to make better climate predictions,” explains Print.

Sulphate aerosol

Sulphur dioxide is a corrosive gas that is harmful to humans and makes rain more acidic. It is released naturally into the atmosphere via volcanic activity but the majority of emissions are caused by industry, mostly through the burning of fossil fuels.

When sulphur dioxide is airborne it reacts with other molecules in the atmosphere to form aerosols. These aerosols act as a nucleus that water vapour clings to, which modifies cloud properties. Thanks to the aerosol, these clouds are brighter and whiter than naturally-forming clouds and reflect more sunlight away from the Earth’s surface, which cools the atmosphere.

Most people are now aware that carbon dioxide has a long lifetime in the atmosphere, which is one of the reasons that global warming is a critical and enduring problem. Aerosols, on the other hand, have a short lifetime and leave the atmosphere as rain within about a week. This means that the effects of sulphur dioxide are local because the gas does not have time to mix evenly in the Earth’s atmosphere.

The sulphur rain is acidic and enters soils, lakes and oceans changing the pH of the environment. Some species are susceptible to more acidic environments: fish eggs, for example, may not hatch if the water is too acidic, and damaged vegetation is a common sight in areas affected by acid rain.


The United Kingdom Earth System Model is a model that simulates interactions between different components within the Earth, such as between ecosystems, ice sheets, oceans and the atmosphere, and which Print uses to investigate the Earth’s atmospheric chemistry. It demonstrates how connected the planet is and how even localised changes in an environment can have effects that circulate around the globe.

This tool is especially important when looking for solutions to global warming. Whilst sulphur dioxide aerosols are harmful, they demonstrate that certain aerosols can help cool down the planet. Print muses that there may be a solution hidden in the model in the form of an aerosol that scientists could release into the atmosphere to cool the planet safely.

“There are ideas about geo-engineering projects to release aerosols into the upper atmosphere to cool down areas locally, but the long-term effects of different aerosols on ecosystems and oceans are currently unknown,” comments Print. “We would want to remove a lot of uncertainties first but it’s an exciting idea.”

Across the skies

Although her background is in physics, Print moved into meteorology and worked at the National Astronomical Research Institute of her native Thailand. When she first moved to Cambridge for her PhD, Print threw herself into college activities. She became combination room secretary at St Edmund’s College where her first job was to help students get home or find accommodation during the COVID-19 lockdown.

“It was the first time I have ever moved abroad so there were a lot of new things to adjust to. For example, I moved in the middle of winter and Thailand doesn’t even have a cold winter!”

“I’ve come this far because my supervisors, Professor Alex Archibald and Dr Paul Griffiths, and my group are really supportive and I’m grateful to be part of a group where more than half of the members are women from different countries and backgrounds.”