At the end of the sixties, oceanographer Carl Wunsch (United States, 85 years old) was teaching at the Massachusetts Institute of Technology (MIT), but calculations from a classroom were no longer enough for him. If he wanted to understand the immense mechanism that regulates the planet’s climate, he had to go out to sea, measure and observe a system so vast that no research had been able to cover it.
That decision would mark his career. The New Yorker became one of the great architects of contemporary physical oceanography by developing methods capable of observing and quantifying the state of the oceans with unprecedented precision.
His work has been described as a revolution. The observation systems he helped promote made it possible to measure more accurately how much heat the oceans absorb, track sea level changes, understand ice loss at the poles, and anticipate some of the most severe effects of climate change. That legacy is what the BBVA Foundation has just recognized with the Frontiers of Knowledge Award.
Question. The ocean plays a fundamental role in the climate system, but for years much of what happened beneath its surface remained out of our sight. How did you manage to study it?
Answer. This has not been the work of a single person. Hundreds, probably thousands of scientists from around the world have participated. What happened in the last thirty years was a complete transformation of oceanography. For more than a century, we depended almost exclusively on research ships. They were essential, but slow, very costly, and could only offer a very partial snapshot of the ocean.
We understood that we needed to observe the ocean as a complete system. At the same time, new technologies appeared, such as satellites capable of covering practically the entire ocean surface, autonomous vehicles that could remain for months or even years taking measurements, and international cooperation among countries that shared ships, instruments, and data. We still need ships because there are measurements that can only be made from them, but now they are part of a global observation system.
Q. What scientific impulse was the most decisive?
A. The fundamental change was discovering that the ocean is much more dynamic than we imagined. For decades, we thought of it as a huge system that evolved very slowly: warm water on top, cold water below, and few relevant changes. Now we know that is not the case. The ocean changes on scales of just a few hundred kilometers and at all depths, from the surface to the bottom. There is enormous turbulence, a complexity that was completely invisible with traditional methods. Before, no one could leave a ship stationary for years observing the same place.
Q. How did the experience of facing both the harshness and beauty of the ocean influence you?
A. When I was a university student, I had a Physical Oceanography professor who convinced me to embark. Honestly, at first I wasn’t very interested. We set sail from Woods Hole [port in Massachusetts] and were caught in a terrible storm. I got very seasick and thought: “This is awful. I will never do this again.” But then the sun came out, the sea calmed, and I understood the extraordinary beauty of working there. It was a completely different way of doing science, very different from sitting in front of a computer or in a laboratory. Since then, I have been lucky to sail to remote and extraordinary places. Few scientific experiences can compare with that.
Q. When did you decide to dedicate your life to the ocean?
A. What first attracted me to oceanography was precisely working at sea. It was an extraordinary experience, both scientifically and personally. Very soon I had the opportunity to lead research campaigns with teams of 20 or 30 people, and that was exciting.
But, over time, I also understood the limitations of that method. I remember one of my last major expeditions. We took a ship from the United States to Cádiz and it took about a month to cross the Atlantic. While sailing, I already knew that when we arrived in Spain, the ocean we had started measuring would no longer be the same. It had changed during the journey. That made me understand that we were trying to describe a dynamic system as if it were a still photograph.
Q. What role does collaboration between countries play?
A. There are two fundamental ideas. The first is that the ocean is global and so is the climate. You cannot understand the climate system without understanding the ocean. The second is that this knowledge is only possible thanks to international cooperation. Some countries provide instruments, others develop digital models, and others deploy scientific campaigns. The big change in the last 30 years has been to accept that the ocean does not belong to any nation, but is a shared system.
Q. After almost half a century researching the impact on the ocean, are you optimistic about our ability to face climate change?
A. Based on observations from the last 35 years, we understand much better how complicated the climate system is and that changes in some regions are very different from those occurring in others. I think we have a clearer understanding of the problems and a better description of what the ocean looks like. The crucial question is whether we have genuine predictive capabilities, and that will depend on the time scale we are considering.
The ocean tomorrow will be very similar to today’s ocean, but the ocean in 10 years will be different. In 50 or 100 years even more so, but we are not sure why. We also don’t know how it would evolve if left alone. And we don’t know how it will react or evolve with increasing levels of carbon dioxide.
Q. Just a few months ago, Donald Trump appeared before the UN denying climate change. What consequences can arise for science and climate action from the fact that political discourses still question it?
A. The consequences of Trump in the United States are terrible. A generation of scientists does not receive funding for their research or cannot find jobs. They deny us funding with the argument that it is all a hoax. It is an ignorant idea about the chemical and physical principles that have been understood by science for more than 100 years. It was known that carbon dioxide would warm the system.
Any serious scientist will tell you that they have no doubt there is a major problem. We see it daily with the extreme phenomena occurring worldwide. This is not a hoax. This is exactly what was predicted decades ago.
Q. What role should scientists take in this context?
A. To raise the alarm, something that the pioneers of climate change study began to do decades ago. The second is to understand how the climate system works, how it is changing, and what risks we face. But there is a very important difference between stating that this will happen and saying there is a high probability that it will happen. Science works with probabilities, not absolute certainties.
We know that sea level will rise, although we cannot say exactly when or how much it will affect each place. If someone announced that Bilbao would flood next week, the reaction would be immediate. But if we say the risk exists within 100 years, some will say that is someone else’s problem. That gap between the times of science and the times of society is one of the great challenges. Scientists must make it clear that there are real risks, even if the time scale remains uncertain.
Q. Could you mention a specific case?
A. We are seeing it with wildfires. No one could predict the exact day they would occur, but we did know the risk was increasing and that we had to prepare. The warnings existed; what was missing was acting on them. Our job is to do the best possible science, clearly communicate the most likely scenarios, and help society prepare for them.
