Eelco J. Rohling on The Oceans: A Deep History

It has often been said that we know more about the moon than we do about our own oceans. In fact, we know a great deal more about the oceans than many people realize. Scientists know that our actions today are shaping the oceans and climate of tomorrow—and that if we continue to act recklessly, the consequences will be dire. In this timely and accessible book, Eelco Rohling traces the 4.4 billion-year history of Earth’s oceans while also shedding light on the critical role they play in our planet’s climate system. An invaluable introduction to the cutting-edge science of paleoceanography, The Oceans enables you to make your own informed opinions about the environmental challenges we face as a result of humanity’s unrelenting drive to exploit the world ocean and its vital resources. Read on to learn more about the ideas in Eelco Rohling’s new book.

How/Why did you become a specialist in past ocean and climate change?
When I was a boy, I actually wanted to become a brain surgeon. But I did not pass the lottery to get into medical school when I went to university. So I thought about what else to study for a year before trying again. I ended up doing geology, and never looked back—I pushed on with that instead of trying medical school again. In geology, I developed a fascination with the past environments in which animals and plants lived that we now find as fossils. So after my BSc, I did an MSc with a major in microfossils and palaeo-oceanography/-climatology, supported by minors in sedimentary systems and physical oceanography/climatology. Things started to really come together when I started my PhD project, for which I started to truly integrate these streams in a research context. That’s when my interest in past ocean and climate change became much deeper and more specific.

Why did you choose to write a book about the history of the oceans?
I discussed a few ideas with my editor Eric Henney, and we gradually brought the various ideas together into this book concept. We strongly felt that the vast existing knowledge about the past oceans (and past climate) needed to be better articulated, and placed in context of modern changes in these systems, and in the life that they sustain.

Why do we need to understand the history of the oceans?
The oceans’ past holds many fascinating pieces of information about how the ocean/climate system works, and how it interacts with life and the planet itself. No other field can bring that information to the table. The oceans’ history also holds important clues about how Earth may recover from human impact, and on what timescales such a recovery may be expected. This brings important context to the discussion about modern human impact.

Does the history of the oceans give any relevant information about their future?
Oh, yes. It illustrates the key processes by which carbon-cycle changes have occurred over Earth history, and whet the timescales were for these changes. It also illustrates which processes we might try to accelerate to drive atmospheric carbon-removal on timescales useful to humankind. Moreover, the history of the oceans provides insight into the developments (and extinctions) of life on Earth, which again gives context about the severity and rapidity of current changes on Earth.

Why does a book about the oceans contain so much about climate?
The oceans are an integral part of the climate system. The climate system is a complex beast that spans the atmosphere, hydrosphere (all forms of water), cryosphere (all forms of ice), lithosphere (the rocks), and biosphere (all forms of life, be it living or dead). The oceans are a vital link in all this, and one cannot talk about ocean changes without touching upon climate changes, or the other way around.

The oceans appear to have gone through very large changes in the past. How do the changes cause by humanity compare?
The human-caused changes are large, but not among the largest that have ever happened. But the human-caused changes are unique with respect to the rates of change: modern changes are 10 to 100 times faster than the fastest-ever natural changes any time before humans appeared on the scene. And, also, human-made changes have significant impacts from many different sides: warming, ocean acidification, physical (e.g., plastic) pollution, chemical pollution, eutrophication, overfishing, etc. Natural changes were not that all-encompassing. So modern changes are very scary in relation to the natural changes that have occurred, even when including major extinction events.

Are humans really causing damage to the enormous oceans and the life they contain?
Yes, for sure.Humans have trouble imagining how their (often little) actions can add up over time, and across the massive population numbers. But we’re on this planet with well over 7 billion people, all of whom at least partly rely on the ocean as a key resource for such things as: dumping waste/pollution from plastics to oil and from radioactive materials to chemical waste and fertilizers; transportation (with spillages), food production/fisheries; war-mongering, exploration/mining, energy production, etc. Added up over our massive human population and increasing technical infrastructure, all of these aspects alone have devastating impacts already, but taken together they are heading down a particularly terminal route.

OceansEelco J. Rohling is professor of ocean and climate change in the Research School of Earth Sciences at the Australian National University and at the University of Southampton’s National Oceanography Centre Southampton.