A Scientist's Life: Kimberly Prather

Kimberly Prather is director of the Center for Aerosol Impacts on Chemistry and the Environment at UC San Diego. She received her bachelor’s degree in chemistry from UC Davis in 1985, and her PhD from UC Davis in 1990. She joined Scripps Institution of Oceanography and the Department of Chemistry and Biochemistry in 2001 after having served as a professor at UC Riverside for nine years.

explorations now (en): What do you do for a living?

Kimberly Prather (KP): I study how aerosols that are produced from different sources such as the ocean impact health and climate. My lab is really interested in how aerosols present in air pollution, the visual things that you see, the haze that you see, how they are formed. We started out trying to understand where those came from, and then we moved into how they were affecting human health, and then we moved into how they were affecting clouds and climate.

en: What are some of the main questions in your field?

KP: One of the biggest questions – the biggest question honestly – with respect to aerosols and climate is in clouds. You don't have clouds if you don't have aerosols. So where do those aerosols come from? How efficiently do they form clouds? 

At the center of every cloud droplet is an aerosol particle and sometimes you can get ice, sometimes you can get liquid. All of those things affect cloud properties, but it's the part in climate models that we understand the least about. So a really big focus of our research is to try and understand the largest source of aerosols, which is the ocean. What comes out of the ocean? It's not just salt. We see that bacteria come out, viruses come out, airborne pathogens come out. All different kinds of pollutants can get released in the surf zone. One of the things we're really interested in is what happens when people who live in polluted coastal zones inhale that air. How does that affect human health?

We've also learned how there's different sources that people never really thought about before, how wildfires can impact our atmosphere, how ships can impact our atmosphere.

en: What tools do you use in your research?

KP: The largest tool we use is the Scripps Ocean Atmosphere Research Simulator (SOARS), which was funded by the National Science Foundation and UC San Diego. It has allowed us to bring the entire ocean-atmosphere system into the lab. We can produce hurricane-force winds, we can produce waves, we can control temperature and we can even make sea ice in SOARS. It’s an amazing one-of-a-kind system.

SOARS allows us to look at future conditions such as increased CO₂ (carbon dioxide) levels in the atmosphere. We can actually pump up CO₂  levels in the system, let that acidify the ocean, let that change the biology, and then let that change emissions so we can look at these feedback loops that you cannot look at in the real world.

At the beginning of my career, the first thing I did was invent an instrument that allowed us to measure the size and chemical composition of each individual particle, one by one, and in real time. These instruments have been moved to places all over the world to try and understand the sources of aerosols that are causing air pollution and other problems in the environment.

en: Describe the Center for Aerosol Impacts on Chemistry of the Environment (CAICE).

KP: CAICE is a center that's been running now for 13 years. It was established after I had been doing nearly 20 years of field studies. We'd been on ships and in airplanes trying to understand the real world, but making measurements in the real world is really hard because so many things are changing at a given time. So what we did was convince the National Science Foundation that we wanted to move that full complexity – the biology, the chemistry, the physics – into the lab in the form of an ocean-atmosphere with all of the components, including waves and winds. Then we could actually study how different things change in the seawater and change what gets into the air. As chemists, we like to turn knobs and look at responses.

One of the big discoveries of CAICE is that there are billions of viruses and bacteria in the ocean, and we've learned that those microbes actually not only control the composition of the seawater, they also control the composition of the air. When the ocean is polluted, they shut down beaches in San Diego. They tell you not to go in the water, they tell you not to walk on the beach, but they don't tell you not to breathe the air.

Once these microbes get into the air, thousands of times more people get exposed to those aerosols. A big push going forward is to understand the potential health impacts of those aerosols that get transmitted over long distances. There are places in the world that are a lot more polluted than San Diego, so we're trying to help other countries, specifically developing countries, come up with ways to understand the air they breathe and the impacts on health. 

en: Why did you want to come to Scripps Oceanography?

KP: I came to Scripps because of the strong focus of climate change. I was recruited here by climate scientists because in trying to understand climate, aerosols were the hardest part to get right. I came and worked with climate scientists on improving our understanding of aerosol impacts on climate, but it's been even better than that in the sense that I've met oceanographers and I've met marine biologists. They've taught me about bubbles, they've taught me about waves, they taught me about microbes. You really need all of those different components and those people working together to really solve the grand challenges that we face moving forward.