Earth Systems on Vacation

As I write this, I’m sitting by the side of the Atlantic Ocean, winding up a 2021 Christmas holiday spent at the beach. It’s been a relaxing and tranquil time, looking out over that water, seasonably cold and silty brown, turbid from the near-constant offshore breeze. Herring Gulls and Double-Crested Cormorants feed just beyond the breakers. Holiday-makers play cricket on the sand or comb the surf zone for interesting shells. Even though the Atlantic is young and shallow in geological terms, sitting watching its ceaseless movement and great mass, it seems immutable.

My vacation reading has been Earth System Science: A Very Short Introduction (2016, Oxford University Press), by University of Exeter professor Tim Lenton, Director of the Global Systems Institute. The book elegantly describes the biological and non-biological cycles that fit together to keep the Earth’s climate in homeostasis over geological time. Lenton starts by presenting the “Bretherton Diagram,” which was first published by NASA in 1986. It describes, at a high level, how the various planetary forces fit together, including inputs from the sun and volcanic heat (leftover from the Earth’s formation), processing by both marine and terrestrial ecosystems, and shows how human activities such as burning fossil fuels and creation of pollutants disrupt global cycles.

Here is a friendly version of the diagram.

The various cycles, phosphorous, nitrogen, carbon etc. often involve living organisms, which influence the nature of the Earth’s atmosphere. In fact, so important is this biological effect that astrophysicists looking for life on other planets use reflected color (an indication of the chemical makeup of the planet’s atmosphere) as indicators of biological activity.

As an ecologist, I’m especially fascinated by the interplay between living organisms and planetary processes. Those relationships can be quite complex. For instance, diatoms (a type of phytoplankton) are single-celled aquatic plants (pictured below) that form the basis of the marine food web, as they are grazed upon by microscopic animals like mysid shrimp (a type of zooplankton). Zooplankton is in turn eaten by everything from anchovies to whales. Phytoplankton sequester vast amounts of calcium carbonate in the water column to make their skeletons. When they die (or when whatever eats them excretes waste or dies), that carbon ends up on the deep ocean floor, where it’s out of commission for a very, very long time. This, and the Earth’s other feedback systems, work in concert to balance planetary temperature, moisture, and chemistry. It loops in plate tectonics, ocean currents, terrestrial erosion, marine and terrestrial biota, and a lot else.

The most interesting part of this scenario is its coordination, in its way like a single living organism, with systems that keep it working together in perfect health. This analogy has been the work of many thinkers, principally Professor James Lovelock, originator of the “Gaia Theory,” first described in is 1979 book Gaia: a new look at life on Earth (Oxford University Press).

However, human activities are upsetting this balance. Ocean acidification, for instance, is kicked off by burning fossil fuels and changing land use practices (see NOAA’s brief commentary) and is abetted by rising global temperatures. Lowering oceanic pH can “melt” the little skeletons of phytoplankton. Not only does this break up the marine food web, but the carbon not taken up in their bodies is then free to be released into the atmosphere. So, instead of sequestering CO2, the oceans now start to produce it. This increases greenhouse gases, which in turn increase ocean acidification in a positive feedback loop with extremely negative consequences.

Over the last 200 years, changes in land use practices play out in many other ways, not just in the marine environment. Lenton talks about the Anthropocene (which I also write about a lot). It is the premise that the impact of human activity has become so profound that we are creating our own distinctive layer in the geological strata of the Earth’s crust, our signature being one of microplastics, chlorofluorocarbons, and chicken bones. Taken as a whole, the future could look a bit bleak. Fortunately, though, it’s still not too late.

A wonderful documentary, Kiss the Ground (Netflix) is something that, in my opinion, everybody who eats food should watch. It’s a layman’s introduction to the concept regenerative farming and describes how bare earth, which is created every few months by modern agricultural practices, destroys the biota living within the soil. This limits the ground’s ability to hold moisture and nutrients, reduces crop yields, makes the land vulnerable to drought, and – if that weren’t bad enough – renders cropland unable to sequester carbon. It seems perhaps like a very specific problem effecting only the farmers’ livelihoods, but on the vast scales that megafarms represent, it sets the scene for another dust bowl and the social disruption that results. The precipitous loss of the world’s forests further exacerbate this.

The documentary makes point, however, that by working with the Earth’s systems, rather than against them we can rehabilitate the land and reverse the cycle of degradation. Another wonderful documentary to talk about this is Fantastic Fungi, which looks at the integration of fungal processes into the lives of other organisms and, in fact, the planet as a whole. Both these documentaries offer a different approach, rehabilitating the soil and making way for better crop yields, greater biodiversity and carbon sequestration. Can this be done on a scale to feed the Earth’s 8 billion people? (Raise your hand if you were alive in 1974, when the Earth’s population was 4 billion.) I’m not sure we have a choice.

Tim Lenton begins the windup up his book by observing that sun will eventually scorch the Earth to the point where it becomes uninhabitable and discusses our options of finding habitable planets elsewhere. I love this stuff – space ships, colonists, dome-shaped greenhouses filled with GM soy – plenty of fodder for the scientist and science nerd alike. The thing is, though, those solar conditions won’t happen for about a million years. I’d say we’ve got a bit of time to get ourselves off-world. To do this, though, we have to survive the next 1000 years. And, in fact, the next fifty. Can we do that given the relentless trajectory of human population growth and urbanization, climate change, pandemics, microplastic pollution, and the catastrophic loss of global biodiversity? Many people have pointed out the fragility of this system and made a call for urgent action: Carl Sagan, Stephen Hawking, Jacques Cousteau, Jane Goodall, David Attenborough, Leonardo di Caprio, Greta Thunberg, to name a few.

Humanity is at a crossroads, more important that any we’ve faced before. It means we have to continue the visionary thinking so many have started, changing our perspectives on the inputs to the system upon which every person on the planet depends. It’s the right-hand side of the Bretherton Diagram. The hardest part of any of this is a paradigm shift to long-term holistic thinking, moving from subsidies that enshrine destructive practices to one of incentives that support regeneration of natural systems. However, time and time again, humanity has shown that it can, indeed, accomplish tremendous feats under pressure. Its this that gives me hope for the future.

Happy New Year to you and those you hold dear.

POSTSCRIPT: On December 26, 2021, a great man passed away. Professor E. O. Wilson, leading entomologist, activist, and bestselling author of many times over, was an inspiration to generations of young and aspiring scientists (including me). His kind and thoughtful approach to elucidating many of the worlds environmental and evolutionary conundrums made him an ambassador for nature that few can match. Ed graciously consented to launch our podcast Love Nature as the inaugural guest for a two-part episode, link. One of his most important efforts, and the thrust of his Foundation, has been “The Half Earth Project,” the push to set aside half the planet for conservation and ecological process. Never have these considerations been more important – his legacy will continue for generations yet to come. This post is dedicated to his memory