Antropoceno XIII – Exemplos de Surpresas ecológicas

Ecological surprise. And ecological surprise is both something that’s been persistent throughout the history of people on Earth, but also something that’s maybe not so much, incorporated in our ecological thinking because it is surprising.335

But what we can kind of, I think, improve how we think about ecological surprise. And the first thing, I think, to think about is really to be aware of how common ecological surprise is. And one of the ways of thinking about this is that, as we’ve increasingly dominated the planet, often our domination has produced a lot of surprising things as went along, not things that people never thought would happen, or no one ever thought would happen, but things that were really missing from the mainstream or the dominant way that people were doing things.

I think four kind of classic examples of surprise from the 20th century that probably most people know about to some extent are these I’ve got listed here.

  • So one’s the use of pesticides to control pests and pathogens worked, but very quickly nature evolved resistance to these in many, many cases. And one of the most famous ones is DDT where malarial mosquitoes rapidly evolved resistance to DDT, making it less effective.
  • But also other ones that have been a bit more surprising was toxins being biomagnified in food chains. One of the classic examples of this is mercury being biomagnified. As people released mercury to the environment thinking it was inert, that it wouldn’t go up in the food chain, but unknown bacteria living in the bottom of the sea turned this into forms of mercury that are organic and could be accumulated. And so you ended up with people being contaminated by stuff that no one expected. And this is also something where you have today people in the Arctic who are distant from all the industries of the planet sometimes have the highest levels of toxins, which are biomagnified in food chains in somewhere distant from where the toxins are produced and used.
  • Another type of example is how agriculture, which has been hugely beneficial to the people, also by changing the disease ecology of local places has led to the emergence of new diseases. One of the classic examples of this is how irrigation led to the rise of River Blindness in West Africa, by providing habitat for, one of the animals that transmits this disease.
  • A final example, that’s especially relevant in North America and Europe, is how the simplification of ecosystems, particularly by removing top predators from land and from oceans, has destabilized these ecosystems, causing them to become more variable, and have more ecological regime shifts. So these are all examples from the 20th century.334

But we can also see, emerging kind of novel social-ecological surprises in the 21st century. And some of these are what we call more regime shifts. Where we’ve had changes in fishing, leading to the collapse of fish stocks. And one of the, most well known examples of this is the Newfoundland cod collapse, which was one of the longest-lasting, most productive fisheries in the entire world, which then collapsed in the early ‘90s in Canada, was closed with the idea that it could recover, but now after two decades of closure it still hasn’t recovered. And people are really not sure why this has occurred. There’s some idea it’s been a transformation of the food web, maybe something with changing climate, marine algae populations, but not completely clear. And if people had known there was the possibility of this collapse that couldn’t be recovered from, or in any short time recovered from, people might have managed this fishery quite differently.

Another example of more of a novel type of connection is this new and relatively recent increase it seems in coupling and turbulence in world oil and food markets. After almost three decades of relative stability in global food prices, we’ve had since 2008 both a lot of variation, and it seems an increased connection between oil and food prices. And this, of course, had big consequences, both in terms of what people have to spend on food and oil, but also some people argue has contributed to things like the Arab Spring, where there’s big changes in what people could afford in their daily life leading to social unrest.333

And I think it’s these types of novel social-ecological connections is what we can expect more and more to occur in the Anthropocene. So how can we understand these?

Well I think two ways of thinking about it is: one is we have these global forces that are changing how local places are connected together, and providing new types of pressure on local places; and the other one is that we’re also just changing how local places work. And I think this is somewhere where you can kind of think about how these sort of social-ecological regime shifts connect to global surprise.

And I think one way of thinking about this is to think about regime shifts in agriculture. So this picture is showing, in a cartoon form, the connection between agriculture and water, and how there are three different ways that the connection between water and agriculture produces regime shifts.332

First, is maybe the most classic, is what people mostly think about water, it’s like rivers and the ocean, what people call blue water. And this is by connecting together different places from running off of land you have connections which can cause regime shifts. But you also have the recycling of water from land as it evaporates, then falls as precipitation. This connection of land and how you change these connections through agriculture can also produce regime shifts. Then finally, there’s sort of this brown water, or water that’s soil moisture, and how you have interactions between plants and soil moisture, and between soil structure and water, can also produce regime shifts.

So this figure is showing how you can have these nonlinear changes at a variety of different scales.

In orange are these generally faster and smaller scale, soil moisture-related regime shifts, in green these very big scale, moisture recycling regime shifts, and in blue these more regional level, blue water regime shifts.

And these types of ecological surprise can occur within a field, or within a whole continent. So the surprise can occur at different levels, but what we really have is in the Anthropocene we’re changing these things at many different places simultaneously. So, we’re also producing multiple types of regime shifts in many different places, and connecting them together in new ways. For example, we have these sort of horizontal couplings across the landscape where, say, agricultural transformation, in somewhere like the upper Midwest in the United States, can produce aquatic regime shifts in lakes, which cause going from having clear water to being murky, and over-fertilized. But also transport across the entire landscapes in the US, through the Mississippi River, can move all these nutrients into the Gulf of Mexico where you can go from having productive fisheries to a dead zone.

So you can have these small scale processes can be aggregated to have an impact somewhere else. And these produce all sorts of challenges to management of how do you both deal with your local problems, but deal with these long distance transport ones?

Secondly, you can have things like with moisture recycling, or the interaction between soil and moisture, and moisture recycling. In somewhere like the Amazon where you have fire (it) can mediate between the ability of plants to grow in different landscapes, and maintain moisture in those landscapes, to have a shift between a savannah and a forest state. But you can also have with moisture recycling over an entire landscape that a savannah doesn’t recycle as much moisture as a forest, making it more difficult for forests to grow. So there can be an interaction between local scale regime shift and a more continental scale regime shift.

And a third one, which is less well understood, is how, say, human activities and climate activities, or animal migrations, can provide teleconnections between different places. For example, how, migratory birds can have their populations increased due to agriculture, and then destroy salt marshes in the Arctic; or how long distance, climate fluctuations can mean that changes in land use in one part in Africa have consequences for rainfall in a far distant part.

So what I think you can think about with ecological surprise is there’s sort of two ways we can kind of look at this.

There’s one from the how do local places function and what ways can they respond surprisingly? But also how can these top-down drivers, or large scale processes, drive these systems in different ways but also connect them in new ways?

So I think, just to wrap up, there’s lots of examples of ecological surprise.

  • That by looking at them from different angles we can get some understanding of what, surprises we know can happen?
  • What are some of the drivers that can cause things that we could expect to happen?
  • But also what are some of the variables that if they change, like nutrients or climate or moisture flow, that [we] could expect to transmit surprises around the world?

That these sort of surprises vary in their impact, but we can expect, as we produce a novel planet, we can expect both more of these surprises, in terms of surprises that we expect to occur, but also in truly novel things in novel types of systems.

And to better understand the potential for both of these, we need to kind of have a better understanding of the ways we’ve been surprised about how we’ve been living on the planet, and how we’ve been able to successfully cope with these surprises.335