The Earth has unofficially entered a new epoch – the Anthropocene. It suggests that humans are the dominant influence on the planet’s ecosystems and biosphere - the sum total of life and non-living material on Earth.
Many ecosystems have changed so radically that it is no longer possible to restore them to what they once were, and in other situations it is not appropriate. Instead we need to look at what we can change, accept the things we can’t, and recognise that humans are now an important part of nature.
Restore, reclaim, reintroduce?
Accepting humans as part of nature will require a shift away from traditional views of restoration and conservation.
Governments and communities worldwide spend enormous sums of money and countless hours of work on restoration projects, aiming to reverse the degradation that we have wrought over the past few centuries.
The United Nations, for example, has agreed to a target of restoring 150 million hectares of land by 2020, costing about US$18 billion each year.
In Australia, federal and state governments have several very large restoration programs targeting, in one case, the Murray-Darling Basin – to protect and restore the degraded flowing waters and wetlands of our most iconic river system – and, in another, the Great Barrier Reef – to maintain and restore the universal value of our most iconic marine ecosystem.
There is an elephant in the room
In most cases, restoration efforts aim to return ecosystems to a state closer to what they looked like in the past and how they functioned before modern society. This target is often termed an “historical baseline” .
Historical baselines are estimated from written, oral, photographic or other evidence of past conditions.
For example, restoration of an ecosystem to an historical baseline might involve removing an invasive species (such as carp) or reintroducing a locally extinct native species (such as bilbies). Historical baselines are inherently problematic, however, because estimates of what is “natural” depend on people’s perceptions, and ecosystems themselves change over time.
Environmental management often now seeks to rehabilitate, reclaim or remediate, all of which involve at best a partial move toward a past state.
The elephant in the room is that many – perhaps most – restoration projects fail to return ecosystems to a state that in any way resembles historical baselines. Governments in most countries still remain focused on management activities that are narrowly restricted to historical conditions (such as eradicating invasive species).
But management actions focused solely on historical conditions do not account for how ecosystems have changed and do not always represent the best course of action for maintaining biodiversity.
New baselines for a new world
In a new era, where anthropogenic pressures dominate, how do we set targets for restoration and conservation?
In many situations, contemporary ecosystems no longer resemble the historical condition, nor are they expected to.
In some cases, the historical condition has gone forever. For example, cities are here to stay and the Thylacine no longer exists. In others cases, the political will to reverse change (such as by removing large dams) does not exist, or else new species or conditions are now simply considered normal (for instance, trout in rivers or dingoes in the outback).
Without enormous technological advances, or alterations to the ways we manage our landscapes and natural resources, we may have to accept new types of ecosystems and their human-modified baselines.
We call these “Anthropocene baselines”. Anthropocene baselines are ecosystems or parts of biodiversity that cannot – or will not – be restored to historical conditions. They are usually caused by socio-economic and ecological (such as invasive species) constraints.
Defining these new baselines represents a shift away from using past conditions in the absence of modern society and provides a new point of reference for managing biodiversity in the Anthropocene. They recognise a reality of the modern world: humans depend on natural resources and, in many cases, biodiversity is depleted or permanently altered - but may still be used sustainably.
For example, the mouth of the Murray River has changed as a consequence of building barrages and draining inflows away from the Coorong. Connected systems are now isolated and species that were never part of the Murray mouth dominate this environment.
Given these massive changes, it is unreasonable to expect the contemporary ecosystem to respond to restoration efforts in the same way as it may have in the pre-European past.
But by delivering environmental water and minimising the effects of other human pressures, we may be able to achieve sustainability.
Should we just give up?
Anthropocene baselines do not mean we stop conserving or restoring ecosystems. Altered ecosystems have tremendous value to humans and wildlife, which must be maintained. Other environments, such as free-flowing rivers in wilderness areas, may function within historical baselines.
Anthropocene baselines should, therefore, never be used as targets for management when restoration or conservation to historical baselines is viable.
The Anthropocene acknowledges humans as part of the environment - if not the most influential part. We are therefore the problem and the solution.
Points of reference for managing nature must balance the unavoidable effects of humans, while ensuring these effects don’t cause further degradation.
This does not mean giving up, far from it. It means setting sustainable targets that include ourselves in a changing world. These new baselines will ultimately represent choices made by people. But these decisions should be guided by scientific evidence – focusing on the long-term sustainability, benefits and costs of different human activities.