Ecologists rarely take the time to define what we mean by an ecosystem. When forced to provide a definition, we’ll come up with something like ‘an ecosystem consists of a community of organisms, together with the physical world they inhabit’. Think of the way a pond consists of fish, algae, and many other smaller organisms; plus the water, gravel, rocks, silt, etc. This is analogous to the way in which economists talk about economies consisting of households, companies, infrastructure and so on; and the way we sometimes talk of communities of people.

The use of such terms encourages us to think that we can divide the world into pieces, then study the pieces individually. An ecosystem here, an ecosystem there. An economy here, a community over there. This reductionist approach certainly makes the world easier to think about. It gives us license to think of each system separately, focussing on its constituent parts in an attempt to gain some insight into what makes that particular system tick. Ecologically, we can think of a grassland ecosystem in terms of grass, soil water, grazing animals and fire, all occurring in one place – then switch to thinking about a forest ecosystems in terms of trees, competition for light, and large mammals, all interacting somewhere else. Economically, we can think about the UK in terms of its developed infrastructure, service-based economy, educated but aging population, ridiculous house prices and flat-lined economic growth – then switch to thinking of Nigeria, with its less educated but younger population, oil-based economy and sky-high economic growth. We can compare across systems too, making generalizations about arctic vs temperate ecosystems, developed vs developing economies, or homogeneous vs diverse communities. And we can develop policies for each system in isolation, such as setting UK interest rates in an attempt to control UK inflation, or preserving a small patch of habitat in an attempt to conserve the species that are found within in it. All the time, we’re reinforcing the fundamental assumption that such a thing as separate ecosystems, economies or communities exist.

Trouble is, they don’t.

First – scale. The use of a term like ecosystem assumes that we can draw a boundary, and declare that the things inside interact strongly with each other, but do not interact with the things on the outside. In practice, we can never draw this boundary. Ever. Try to draw that boundary, and you will not be able to say why you did not draw it much larger, or much smaller. Draw it around a wood. Why not the whole valley – after all, deer roam over the whole thing? Then again, an individual tree supports untold numbers of insects, microbes and fungi, so why not call that an ecosystem? Draw the boundary around an island. Why not the whole archipelago – after all, seabirds and large fish roam over the whole thing? Then again, why not just one tiny pond at the top of one mountain? Come to think of it, don’t people talk of the gut contents of one animal – even of one insect – as being an ecosystem? So isn’t the island really made up of millions of ecosystems?

At first glance it seems like economics doesn’t have the scale problem, because it can work with the economy of one country, like the UK. But what about dependencies like Gibraltar? Brits abroad? UK-based multi-national companies? Other multi-national companies with interests in the UK? The EU? On the other hand, it is obvious that London is very different to the English Midlands, vs Wales, vs Scotland, vs Northern Island. Wouldn’t it make more sense to say that each of those counties has its own economy? What about York vs Hull? Central York vs the suburbs? What these questions make clear is that the traditional economic approach of breaking the global economy into nation-sized pieces is just a convention.

As if scale wasn’t hard enough, we have our second fundamental problem – interconnectedness. Even if we could find a well-defined chunk of the world that appeared to be a nice, neat ecosystem (or economy), we would straight away find that this system is strongly connected to others, most notably by actors who move between them. It is mind-blowing to think of the billions of birds that move enormous distances across the Earth’s surface, eating in some locations, reproducing in others, and in the process moving nutrients and energy between systems that would otherwise by mostly isolated. My instinct is that this ‘global migration connectome’, as I like to call it, probably plays a crucial role in stabilizing the biosphere – although nobody knows for sure. It is equally mind-blowing to realize that, to a first approximation, every species of microbe on Earth gets everywhere, in the form of spores. Untold trillions of such spores are exchanged between every piece of soil, every pond, every inch of the surface of the ocean, and the skin of every living thing, every day – a daily global information exchange that puts the internet in the shade. That’s why you can make bread by leaving flour and water on a windowsill. That’s why you can create a thriving wildlife pond within one year, just by filling a hole with water then leaving it alone. And that’s why – thank goodness – everything natural rots away when it dies. Then consider that we humans are making ecosystems all the more connected. As we move around all of those goods, and people, we bring along organisms, such as larger plants and insects that would not be able to cross oceans without us; sometimes, but by no means always, with disastrous results.

Similarly with our economies. When the UK imports the majority of its raw materials, manufactured goods and food, how we can we talk of ‘the economy’? Think of the daily migrations of people between where they live, and where they work (I know of at least one person who is crazy enough to migrate between Norfolk and London every day…); the seasonal migrations of people following seasonal work or seasonal pleasure; the diasporas that have reshaped our global economy for millennia; and the multinational companies, NGOs, and family and religious networks that tie us all together in ways that none of us can understand. Consider also the way that ideas and technologies have spread around the world, from agriculture to siege warfare to printing to computers. Then consider the way that technology is, year on year, making the global economy even more interconnected. Globalization I think they call it.

Now, both economists and ecologists do recognize the problems with defining ecosystems and economies, but they tend to think of these problems as riders that should come along with the key, and sensible, assumption that the world can be divided. The picture in their minds is like the one on the left below – a set of ecosystems (or economies) connected together in some way, with the connections becoming stronger in the modern world. This viewpoint, however, is simply wrong. The biosphere has always been strongly connected, with or without the addition of human transportation networks; economies have been globalized for millennia; and more importantly, the nodes in these networks – the ecosystems and economies – simply do not exist!

It would certainly be more honest, and it might be more useful, to admit that the global biosphere and the global economy are actually scaleless and highly connected networks – like the picture on the right. Each network consists of very large numbers of complex actors (organisms, or humans) bound together by a dense, continually shifting, network of complex interactions. Any attempt to break this network into pieces is wishful thinking.

Such networks are hard to understand, and the mathematical study of them goes back only a few decades at most. As a result, we have few general results to go on. We do know that, at small scales, they can exhibit all kinds of interesting, and largely unpredictable, behaviours. Regions of such networks can go through long periods of apparent stasis, only to suddenly change in response to some small external influence from elsewhere in the network. On the other hand, they can have a remarkable ability to rewire and self heal, preventing the system-wide collapses that can affect simpler systems, and recovering from such collapses as do occur. To a large extent, it is exactly the variation at smaller scales that enables stability at larger scales, suggesting that policies that seek to maintain local regions (e.g. a national economy or a local patch of habitat) in a constant state could be misguided. Otherwise, we’re largely in new territory as far as policy is concerned. Nonetheless, it might be better to try making policy based on a poorly understood truth, than on a well-understood lie.

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