As atmospheric scientists look to the future, they often make models to predict what the climate will look like. These models take into account the transfer of energy and materials throughout the atmosphere and ocean. However, North Carolina State University Professor of Marine, Earth and Atmospheric Sciences Nicholas Meskhidze has discovered that these climate models are neglecting the air-sea transfer of one element: iron.
“Global models can do a good job in terms of first order understanding,” Meskhidze explained. “But if we want to go beyond that, and if we want to reduce the uncertainty in our predictions of future climate, then there are the processes that we need to start paying attention to, and I think this iron is one of them.”
Three billion years ago, usable iron was plentiful in the ocean. But as organisms evolved and started producing oxygen, it started diminishing. Yet some still appears, and Meskhidze is on a mission to figure out how and why it gets there in hopes of using this information to better inform future climate models. Meskhidze soon found that the process of iron deposition is more complex than it seems.
“It's a function of soil mineralogy, atmospheric transport time, relative humidity, temperature, different organics that can be present in the sun, in the atmosphere and sunlight,” Meskhidze said.
Meskhidze started his project by looking at how iron from mineral dust interacts with other gases in the atmosphere and how it gets transferred from its mineral form into a form that is more bioavailable, or accessible for marine organisms.
“Eventually we got to the point when we could predict how much iron in potentially bioavailable form gets deposited to the ocean,” Meskhidze recounted. “But then I started thinking, ‘What happens to this iron when it hits the ocean?’”
Because the acquisition of iron is difficult in the ocean, aquatic microorganisms developed elaborate ways to maintain levels of bioavailable iron required to sustain marine organisms. Meskhidze began to experiment with different atmospheric organics, like the ones in the ocean, to see how these organics could extend the lifetime of bioavailable iron after its deposition to the ocean. However, he realized his project needed more than just an atmospheric scientist like himself.
“All current problems are complex and multi-disciplinary so just one person can’t easily solve it,” Meskhidze remarked. “What I wanted to do was to bring both the ocean and atmospheric sides to sit down together and talk about this problem: How does that iron, that gets mobilized into the atmosphere, get into the ocean and stay in this bioavailable form.”
In 2018, Meskhidze co-organized a Telluride Science workshop with Christopher Völker to do just that. Titled “Identifying and Characterizing the Processes Controlling Iron Speciation and Residence Time at the Atmosphere-Ocean Interface,” the workshop engaged ocean and atmospheric scientists from all over the world. At the workshop, the group came up with an idea for a perspective paper on the iron atmosphere-ocean biogeochemical cycle and where future research should be directed, which was published the next year. To Meskhidze, the collaboration between different disciplines was especially important to understanding the mechanism(s) of iron transfer.
“This is kind of an area where neither oceanic scientists nor atmospheric scientists were working too much because it's in between, it’s in this transition,” Meskhidze explained. “The process happens within minutes, which means that global models would have a real hard time trying to capture those kinds of processes. If you’re running a global model, you cannot write a code that will explain the physics going behind it. You have to come up with some kind of parameterization.”
Despite the pandemic, the collaborative work originated in 2018 is ongoing, and Meskhidze is excited about the progress that’s been made. His group will resume their in-person discussions in Telluride in 2022.
This is the eighth in a series of scientist profiles highlighting how Telluride Science scientists have found new ways to collaborate and continue scientific research to address global challenges. To learn more about Telluride Science, visit telluridescience.org. For more on Nicholas Meskhidze, visit meas.sciences.ncsu.edu/people/nmeskhi/.