Countries worldwide are busy negotiating a post-2020 biodiversity framework. This framework aims to ‘bend the curve of biodiversity loss’ by stopping the decline of nature in the next decade and enhancing biodiversity by 2050. The first part of this goal has caused some confusion in the lead-up to the negotiations and our recent paper shows that failing to address this could result in prolonged biodiversity loss over the next century.
Last year, participants at the Trondheim Conference on Biodiversity proposed the goal of ‘zero loss’ of species and their habitats. This seems like the necessary first step of bending the curve. How else can we increase biodiversity by mid-century without first ending current declines?
The trouble with zero loss is that it might block necessary economic activities that transform natural habitats for roads, mines, farms and factories. Maybe we should rather balance our use of biodiversity with restoration efforts? In this way we could still allow for important economic development, as long as we also enhance nature somewhere else. We refer to this concept as ‘no net loss’ of biodiversity.
No net loss policies appeal to us because they permit development without harming nature. They are so appealing that no net loss of ecosystems is even one of the five long-terms goals in the draft version of the post-2020 biodiversity framework under the Convention on Biological Diversity:
“No net loss by 2030 in the area and integrity of freshwater, marine and terrestrial ecosystems”
A first blush it seems as if ‘no net loss’ is the same as ‘zero loss’, but with the benefit of permitting economic development. But nature isn’t made up interchangeable units that can be tallied up on a balance sheet. Instead, nature is a system of connections and feedbacks that convey ecological resilience and allow healthy ecosystems to recover from disturbances. When resilience is lost, damaged ecosystems flip into alternative states of collapse.
Using computer simulations, we showed that no net loss policies that ignore ecological resilience lead to biodiversity losses that linger for decades. This happens because the impacts from development erode both biodiversity and ecological resilience. Although we can compensate for biodiversity losses with restoration actions, the effects of reduced ecological resilience remain, locking systems into states of decline.
Ultimately, the post-2020 biodiversity framework should acknowledge the distinction between zero loss and no net loss. If we are serious about bending the curve of biodiversity loss, then we need to bring current rates of loss to zero. So, rather than balancing the losses from development with gains from restoration, the post-2020 biodiversity framework should focus on identifying and retaining fixed biodiversity targets that shouldn't be transgressed. This will maintain ecological resilience and ensure that we keep nature in a healthy and desirable state.