The United Nations marks June 8 as World Oceans Day, an opportunity to celebrate the ocean and how it supports life on Earth.
As director of Florida State University’s Center for Ocean-Atmospheric Prediction Studies (COAPS), Eric Chassignet leads investigations into the physical processes that govern the ocean and its interactions with the atmosphere. He spoke about his research and questions scientists are trying to answer about the ocean.
What are some of the factors that make the ocean so important?
The ocean covers about 70% of the Earth and plays a major role in transporting heat from the equator to the poles. Ninety-seven percent of the water on Earth is in the ocean, and most of the rain on Earth comes from evaporation over the ocean. The ocean can also store about 50 times more carbon dioxide than the atmosphere, helping control temperatures. But that may be changing. Since 1870, oceans have absorbed most of the carbon dioxide produced from burning oil and gas. However, research shows that the ocean’s ability to absorb atmospheric carbon dioxide might be declining, therefore leading to an increase in CO2 concentration in the atmosphere and an amplification of the Earth’s greenhouse effect.
Of course, there are other reasons why the ocean is important. It is a vast and diverse ecosystem and a major source of food. For many, the ocean is also a source of livelihood and a place for recreation and relaxation.
Tell me about your research.
My main research interest is on the role of the ocean in climate variability using computer models and observations. I am especially interested in the dynamics behind ocean currents and ocean eddies and their impact on the world ocean circulation. Ocean models are complex computer programs that simulate the physical state and dynamic properties of oceans. At COAPS, we use global and regional models to study processes such as the ocean’s response to a hurricane or to improve both short- and long-term ocean forecasts. Just as meteorologists make weather forecasts, we do the same thing for the ocean.
While changes in currents do not affect the public as much as changes in the weather, it does matter. If you’re a fisherman, for example, you would like to know where there is a change in sea surface temperature, which identifies the edge of a current where fish congregate. The Navy needs to know the temperature distribution at depths for operating their submarines. An in-depth knowledge of ocean currents saves fuel when routing cargo ships. And most importantly, ocean predictions are essential in determining where oil may go in case of a major spill such as the one that occurred in the Gulf of Mexico in 2010.
How has research changed during your career?
The biggest aspect is in computing. The computing power of a smartphone is as much as a supercomputer of the 1980s. What we can do now with supercomputers is just amazing. Technology, and the type of modelling we can do, has changed so much in the past 40 years. Now we integrate global computer models at extremely high resolution, as small as 1 kilometer.
What are the big unanswered questions in ocean-atmospheric forecasting?
Our biggest challenge is understanding the interaction between the ocean and
the other Earth system components (atmosphere, the frozen parts of the ocean and land). We are reaching a point in the technology where one can perform Earth system predictions, not just weather or ocean current predictions alone. For example, how does the melting Arctic ice cover modify the ocean’s properties? How does the atmosphere respond to changes in the ocean? What is the importance of the ocean in our changing climate?
What’s something that would surprise people to learn about the ocean?
The amount of mismanaged plastic waste in the ocean. And where it ends up.
We know that 80% of litter in the ocean comes from land sources, and plastics are the most abundant type of litter. At COAPS, we developed a global marine litter model to show where litter in the ocean comes from and where it goes. In this model, you can see the trajectories of litter as it is moved around by the ocean currents.
For example, some of the plastic debris that originates from the east coast of the United States travels across the Atlantic Ocean to Western Europe. It might surprise people to know that a piece of trash dumped off the west coast of the United States can travel all the way across the Pacific and Indian oceans and end up washing ashore on the east coast of Africa.
It shows just how interconnected we all are, and that is all through the ocean.
