Eve is here. As you may have noticed, I am opposed to optimism. Because optimism leads to complacency (see “The Dark Side of Optimism” for a long treatment). And especially when the stakes are high: what happens to civilization and the survival of species other than our own. So this kind of fun talk about environmental tipping points really pisses me off (admittedly, the Iran war raised my bile baseline level). But perhaps a larger audience of climate change experts will tell you that my reaction is too reflexive and that there is some truth to the following argument. Perhaps the upbeat message with its workaround (“things don’t have to be an absolute disaster”) is well-calibrated.
By Vera Starinchak, researcher and incoming PhD candidate at the Brand Institute. student at the Yale School of the Environment. Her research focuses on forest resilience in the face of climate and land use change. She is also a fall 2025 graduate of the Young Voices of Science program. Originally published in Undark
Imagine a Jenga tower on the brink of collapse when the last critical block is pulled out. Or a book standing on an old shelf will finally fall over with the slightest impact. Or, as Malcolm Gladwell wrote in his best-selling book, The Tipping Point, it could lie dormant for years until the right conditions are created, then suddenly explode and start an epidemic.
In each of these scenarios, incremental, small changes eventually lead to a tipping point. At that moment, the status quo becomes untenable and everything changes in an instant. The idea of tipping points, popularized by Gladwell, has become mainstream in the past few decades. Tipping points have been described across a variety of settings and scales, from individual life events to complete changes in social behavior. Our planet is no exception.
In the natural world context, a tipping point marks a threshold at which the severity and intensity of an environmental disturbance (deforestation, fire, drought, permafrost thaw, etc.) disrupts the equilibrium of an ecosystem, fundamentally altering its function and composition, beyond its ability to return to a balanced state. For example, suppose the balanced state of the ecosystem is a mature old-growth forest. In that case, the disturbed condition would be characterized by extensive tree mortality and a more open canopy. Such tipping points have generally been portrayed as dangerous but avoidable.
However, in 2024, average global temperature increases will exceed 1.5 degrees Celsius (2.7 degrees Fahrenheit) for the first time, and this fall marks the first time a confirmed global tipping point has occurred (widespread coral reef die-off). These 11 what-if scenarios are becoming reality. While tipping points are becoming more common, their outcomes are still often described in vague, generalized and catastrophic terms, and all tipping points are often conveyed as distant scenarios that, once crossed, indicate an immediate end to our ability to make a difference in conservation and climate change mitigation.
However, not all tipping points are the same, and their effects can often take years to manifest. For example, systems like coral reefs are highly vulnerable to large-scale bleaching events that are immediate and irreversible once dangerous thresholds are exceeded, whereas systems like glaciers respond at a much slower pace to disturbances such as global warming.
As an ecologist who studies the resilience of tropical forests, I have seen firsthand the contrast between popular depictions of tipping points (and their consequences) and the reality on the ground. I work in the Amazon rainforest, which is perhaps one of the best-known examples of a system with the potential for catastrophic tipping points. The idea, called the Amazon tipping point hypothesis by experts, originally estimated that 1,140 percent of the Amazon had been deforested for agriculture and other human needs, and that many areas of the Amazon would be reduced to savannah-like conditions. These will consist of hotter, drier climates dominated by short shrubby plants. This hypothesis also suggested that, when combined with the stress imposed by changing climatic conditions, this change could occur at the lower end of 20-25 percent of deforestation.
In particular, recent estimates indicate that deforestation levels in the Amazon have reached approximately 17 percent, leaving more than a third of the remaining Amazon devastated.
Growing up in the United States, my perception of the Amazon was shaped by nature documentaries like “Our Planet,” which featured lush, misty green forests that were home to fascinating animals such as jaguars, anacondas, and pink river dolphins. But on my first visit to my lab’s research site, the Tanglo Research Station in central Brazil, what I encountered was more like the soybean fields on my grandparents’ farm in Ohio, separated by large perfectly rectangular patches of very dry short forest.
This fragmented landscape I encountered is definitely an ecosystem in distress. Over time, the region’s dry season has lengthened and extremely hot days have become more frequent. Fires are not typically naturally occurring in the Amazon, but are widespread because widespread human ignition sources and hotter, drier conditions facilitate fire initiation and spread within the forest. Deforestation intensifies these effects by reducing the range of cooling and water circulation services provided by trees. Collectively, these factors are really stressing these forests from almost every angle.
However, the concept that the Amazon is on the brink of irreversible transformation into a grassy savanna remains unclear. The results of an experiment that began in 2004 to burn large tracts of forest in Tanglo to simulate the effects of severe wildfires suggest that the future of the forest is more complex. Initial findings show that repeated fires, particularly during the driest months, have killed trees and opened the canopy to let in sunlight. Sun-loving non-native grasses quickly established themselves, and because grasses input much more fine fuel during fires, the intensity and severity of subsequent fires were even worse, increasing forest loss and inhibiting forest regeneration.
The burning experiment at Tanguro ended in 2010. The forest has since recovered, and our lab is part of a huge network of researchers studying what happened next. Amazingly, when we look at the forest today, it looks as if it has always been there. What’s even more remarkable is that the grass that once occupied the understory of the burn site has nearly disappeared.
The resilience of forests is at work. Above: Impact of six years (2004-2010) of intermittent experimental burning on the Amazon forest in Mato Grosso state, Brazil. This has led to widespread invasion of non-native grasses and forest degradation. Below: The current forest after 16 years of recovery. Although the grass has now significantly reduced and the tree canopy is covered, it is still in disrepair. Visuals: Paulo Brando, Leandro Maracipes
However, don’t get ahead of yourself. Forests remain highly fragmented. This is still next to strictly managed farmland. Droughts and heatwaves are more prevalent than ever and will only get worse. We are still working to understand how the composition and function of burned forests have changed over time. However, the invasive grass-dominated ecosystems that emerged post-fire, after significant periods without fire, are almost nowhere to be found.
This is consistent with the larger consensus that has accumulated since the creation of the Amazon tipping point hypothesis. There is a lack of clear evidence that a single disturbance, such as 40 percent deforestation, triggers a system-wide tipping point from forest to savanna. Rather, many of these failures act like hammers, repeatedly attacking the system. The combined effect of all these disturbances could potentially trigger a tipping point, depending on the region, scale, intensity, and timing. However, it seems unlikely that post-tipping point conditions will immediately and permanently become savannas, and our study shows that forests can still recover if you remove even one of these disturbances from the equation. This is why it is so important to reduce deforestation and improve fire management in the Amazon and forests around the world.
On a broader scale, our planet is resilient, even through 1.5 degrees of warming. In many cases, systems may still have the ability to recover if we act diligently to stop disruption, promote resilience, and reduce the time it takes for systems to cross tipping points. And this is a message that cannot be captured in typical tipping point conversations.
Fortunately, we know how to promote the resilience of natural ecosystems, and by communicating these as powerful post-tipping point tools, we can inject a hopeful message into otherwise heavy conversations. Conservation, restoration, and centering and supporting the knowledge and action of indigenous peoples and local communities living in threatened ecosystems are all critical.
Importantly, this does not mean that the concept of tipping points is useless. Thresholds and clear numbers based on scientific research have a huge impact on clear management and policy guidance. However, it is equally important to communicate the importance of sustained conservation actions, intervention pathways, and positive, actionable messages once tipping points are passed.
So the next time you hear we’ve crossed the point of no return, don’t despair. These tipping points are not necessarily the instantaneous, unstoppable dominoes that are portrayed. Dig deeper, ask questions and find out what you can do. And most importantly, don’t lose hope.
