Arquivo de etiquetas: frontieras

Antropoceno XXVIII – As novas fronteiras

Novel entities

Hello, my name is Sarah Cornell and I’m an environmental researcher at the Stockholm Resilience Centre. The first thing I need to do right now is explain what I mean by the term novel entities. Back in 2009, Johan Rockstrom and colleagues argued that there should be a planetary boundary for chemical pollution. But they weren’t able to define a quantitative value for that boundary.551

In recent years this challenge has been a topic
of a lot of conversation between Earth system scientists, my own field of research, and ecotoxicologists, people who deal with the problems of chemical pollution.

We now refer to the process as the release of novel entities into the environment. Why did we change the name? Well, first of all it signals that we’re focused on the role of human-caused changes in the Earth system that can fundamentally alter the way that biogeochemical, ecological and physical processes happen at the global level.

The changes we’re concerned about are the ones where human technological capability lets us bypass the normal ecological and physical self-correcting, co-evolutionary behavior of living organisms interacting with the physical processes of the planet.552

When I talk about self-correcting behavior I simply mean that the toxic substances that exist in nature generally break down in nature. To give a really blunt example, an organism will die if it’s exposed to natural toxic substances, but natural processes will also tend to break down and disperse the toxin in question. And there are many chemicals that have toxic effects, some of them like salt, or alcohol, or kerosene, or snake venom can be very toxic indeed, but they are dissipated in the environment because living organisms have co-evolved with the processes, the chemical processes, that produce them.553

Our human technical capability lets us put together chemical substances in combinations that did not exist before, and that no ecosystem has been adapted to, or can adapt to, on the time scales that we see for technological change.

Chemical toxicity on its own isn’t necessarily the problem, it isn’t a systemic or planetary problem. Life can and does adapt to toxic substances. And we don’t need a planetary boundary for issues that are local and temporary.


We’re concerned about Earth system processes. So for that reason the term chemical pollution was too general for our purposes. But we do need to be aware of the planetary risks of creating these fundamentally novel substances that can’t be metabolized, that don’t break down easily in the environment, and that interfere with the physical and ecological processes on which all of the other Earth system functioning depends.

We’re concerned about humanity’s capacity to mobilize some natural toxic substances in new ways, in new forms, and in an ever-accelerating rate. The most obvious category of novel pollutants is the completely new synthetic substances. We can’t say that there’s a Holocene background level for these kinds of compounds. Compounds like persistent organic pollutants for instance, often called POPs.555

Another Earth system problem is the production and the environmental release of highly reactive molecules that contain some of the toxic or radioactive heavy metals. These organic compounds can be transported through water and the atmosphere to some of the most remote parts of the Earth system. Mercury is one very concrete example. Volatile organomercury compounds are emitted into the atmosphere and they can be transported and they expose ecosystems, and human populations, to very high levels of pollution very far away from their original sources.

Here we have a few other examples where Earth system functioning has already been impacted by human technological capability to produce new chemical substances. They’ve all had serious, if not necessarily catastrophic yet, impacts. You’re probably familiar with the problem of the chlorofluorocarbons, the CFCs, that led to the depletion of atmospheric ozone in the upper layers of the atmosphere.

They’re also powerful long-lived greenhouse gases, so in that sense they’re chemical substances that interfere with the physical functioning of the Earth system.

Another very well known example is the problem of DDT, a synthetic pesticide that kills agricultural pests and mosquitoes, but many other organisms too. DDT accumulates in fatty tissues and so it can be carried through the food chain. It persists for years in soils and sediments. It has now become a globally distributed problem and it has fundamentally changed the way that ecological processes happen in the Earth system.

As a result of planetary experiments like these we know that particular traits make novel entities a problem in the Earth system. Toxicity is important but we must take a big picture view that goes beyond just the effects on individual organisms through to ecosystems and actually the whole planet. Problem substances persist in the environment. This means that they can be transported large distances around the world, either in living organisms or through water in the atmosphere. We see systemic effects when these substances accumulate in living tissue. For instance, the problem of bioaccumulation makes substances become more concentrated as you work up the food chain. So, some of our keystone species in ecosystems are the ones that are most vulnerable.

Another important trait in this is the very high risk of irreversibility. Sometimes this is just because a problem has become globally distributed and we can’t deal with it directly, but in other ways it’s because we have passed a physical or an ecological tipping point in the way that the Earth system functions.

All of this means that we are still no closer practically to achieving a single quantitative boundary value for chemical pollution or these other novel entities. A major practical obstacle is the sheer variety of chemical substances, of radioactive substances, and of the many forms that these substances take once they’ve been released into the environment and are subject to chemical and biological changes.

Because of this colleagues at Stockholm University, and many places around the world, are working on defining principles that will let us identify planetary risks associated with the creation of these novel entities and their release into the environment.

We really want to improve the way that we screen for hazards, and the way that we manage and monitor environmental changes caused by novel and synthetic substances in the environment. One of the big implications of this is that we simply must halt the environmental release of the most problematic substances.

556The big challenge is we don’t know which those substances are usually until it’s too late and the impacts are already seen in the environment. So this also means that we must apply the precautionary principle much better.

The risks of environmental change are not known very often with some of the compounds that we’re creating, and certainly with many of the compounds and technologies that we’re capable of creating. We, here at SRC, and in many of our global change partner organizations, [are] encouraging dialogue about this new area of research.

It requires new interactions between science, and policy, and business, and actually between everybody in society, because we’re all exposed to these new global risks and we need to deal with them together.