Tipping points are something that we hear a lot about in the media, often about climate change. With the recent catastrophic fires in Australia, a discussion about tipping points is especially important because tipping points could alter, forever, our economic wealth.
Before we find out what a tipping point is, first, let’s explore what does the actual tipping. In science we call it a system. A system sounds complicated but it’s really a bunch of things with relationships creating something we can identify: a city, a family, a climate or an ecosystem.
Forest ecosystems are an example of a system. In Australia, our forests have evolved over thousands of years to the local climate and to indigenous, and then western, land management. They have their own distinct character and identity.
Our forest systems have been highly resilient. Despite many impacts (land clearing, weed and pest invasions and wildfire) our forests continue to bounce back from disturbance. This is because of amazing adaptations. They have seeds that are heat resistant or require heat to germinate. Epicormic buds are protected from fire by tree bark and some species have the ability to coppice (grow back from the trunk).
The past is not just the past, its also the future
Just because they have been resilient in the past, does not guarantee the same in the future. Resilience can change suddenly when important relationships in the system wear down. This can occur from a large impact or many incremental, cumulative impacts. The first is more spectacular but it’s the latter that often goes unnoticed. It’s also the most common.
Behind the massive wildfires are incremental, cumulative carbon emissions that have increased since the industrial revolution: the trips we make in our car, the times we’ve left that light switch on and the hectares of forest cleared to produce each of the newspapers we’ve read. By themselves they don’t seem consequential, but together they are. These incremental, cumulative impacts ‘wear down’ the inbuilt mechanisms that buffer disturbance and keep forests resilient.
When resilience hits rock bottom
When buffers no longer work, the system crosses a tipping point. All the relationships in the system break down and are replaced by new ones. The new relationships are radically different, making the new state of the system unrecognisable. We cannot predict what the new system looks like, but we can get some hints from prior examples (threshold database).
For instance, significant research studied how overgrazing of western NSW Mallee vegetation caused this ecosystem to cross a tipping point. Overgrazing reduced the vegetation cover. With less vegetation there were less roots to hold the soil together. This caused soil to erode. A chicken and egg scenario occurred. Soil could only return with vegetation to ‘anchor’ it and vegetation could only return if there was soil to grow in. This explains why crossing a tipping point is, from a practical standpoint, irreversible.
After widespread wildfire, soil is vulnerable to erosion because vegetation cannot keep it in place. Heavy rains after our recent wildfires could have eroded the very soil necessary for vegetation and biodiversity recovery. This time those rains might have held off for just long enough. Next time we might not be so lucky.
Tipping points are a problem for all of us
The risk of crossing forest tipping points is not just a rural problem. Our national economy relies heavily on forests. Direct revenue from forest products is relatively small but critical for some regions. But forests also provide other supporting services to agriculture affecting how profitable and viable farms are. Services provided by forests to agricultural land prevent flooding, purify water, aid pollination, protect land from pests, increase retention of water in soil, and regulate climate by storing carbon and producing oxygen. The value of these ‘supporting’ ecosystem services is typically much higher than those that are traded in our economy.
It’s not just forest tipping points we must be aware of. Tipping points commonly cascade to other tipping points. Loosing ecosystem services and increasing wildfire risk to farming will reduce farm viability (increased costs, lower returns, uninsurability etc). This reduces rural town viability and increases food prices. Increasing food prices reduces the viability of city household budgets and disposable household income. Reduced retail sector viability will compromise the national economy. Everything is connected.
So, here’s some good news. Even at this late stage, we can avoid tipping points being crossed in our forests. Understanding how tipping points work shows us where we need to focus our actions. If we don’t address the incremental, cumulative carbon emissions that have ultimately led to the wildfires in Australia, then all the investments into farm viability, small rural business viability and biodiversity will be like burning money itself. Justifying this is easier right now when the consequences of not doing so are still so clear to us all.