Photo courtesy of cliff mUsial ’21
On Monday, Dec. 9, Dr. Sally Warner, while visiting Hamilton as a candidate for the position of Assistant Professor of Environmental Studies, gave a lecture on the importance of turbulence in climate change. Dr. Warner is currently a research associate at Oregon State University. Her recent research, “focuses on understanding how heat gets into the ocean, specifically how turbulence mixes heat away from the surface into deeper water where it is stored for longevity.” In her lecture Monday, Warner began by explaining how turbulence functions in the chaotic movement of fluids in the ocean, much like the turbulence we experience in the air flying in airplanes. She used a live demonstration of the way that saltwater and freshwater mix to further her point.
Warner’s demonstration divided a chamber of saltwater from a chamber of freshwater in a glass container. By shining a light at this container, its shadow showed that as turbulence disturbs the water, the water mixes together.
In her research, Warner studied a similar movement of water in the oceans. She explained how she measures the rate of the movement of water in the equatorial pacific. One specific part of the equatorial Pacific, off the coast of South America along the equator, is expected to be more significantly impacted by climate change than other parts of the Earth’s oceans. Warner studies the mixing and turbulence of water in this area due to its irregularity. As the climate changes and the average global temperature rises, so will the temperature of surface seawater. However, deeper water will remain at a cooler temperature and be less likely to mix and trade nutrients with the warmer water, Warner explained. Mixing ensures the distribution of both pollutants and nutrients and is essential to the health of the oceans.
This is especially important in the context of El Nino, a series of climatic changes occurring every few years that develops in the Pacific Ocean near-equatorial South America. Models predict that the El Nino area will be significantly colder than what her research shows. This is a problem because El Nino affects temperature all around the world, so if it causes temperatures to be warmer than predicted, then the effects of climate change will be much worse than currently thought. There is an amount of mixing of the warm surface temperature water with the colder layer beneath it. Warner explained that this regulates the intensity of El Nino’s effect on the temperature in multiple regions on earth. However, if the surface temperature continues to rise, then mixing gets more difficult because of the density difference, so the temperature will stop being regulated, making the areas that El Nino effects much warmer.
According to Warner, “in the deep ocean, turbulence is weaker and the physics leading to mixing less well known. Numerous measurements indicate that deep turbulence is too weak to mix the water the way it appears to be mixed in the deep ocean. One possibility we are investigating is that the deep water is mixed at the ocean’s boundaries, where turbulence is strong, and then transported away from shore and to depth by processes that are not yet understood.”
Warner’s field remains a frontier in environmental science, and she hopes to continue her research as a professor of Environmental Studies at Hamilton. She is interested in studying turbulence and mixing in the Great Lakes or even in smaller lakes closer to the college. Warner’s specialty at Hamilton would be Environmental Data Science. Her research relies heavily on analyzing extensive data and would bring this experience and knowledge to Hamilton students as a professor.
