Will Earth hit a climate "tipping point?" Here's why experts say this framework is problematic

Will Earth hit a climate "tipping point?" Here's why experts say this framework is problematic
Fecha de publicación: 
18 March 2024
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People who follow climate change are often told there is a "tipping point," a single moment after which it will be too late to reverse the damage caused by our excessive use of fossil fuels. Yet experts say this concept is misleading, with one scientist — James Hansen, who played a key early role in raising climate change awareness — describing the phrase as "greatly overused and misused."

"The tipping point concept is greatly overused and misused."

Powerful institutions seemingly disagree. The World Economic Forum uses the phrase "tipping point" when describing the various environmental consequences that will ensue once Earth warms more than 1.5º Celsius above pre-industrial levels. The European Space Agency declares that "climate tipping points are elements of the Earth system in which small changes can kick off reinforcing loops that ‘tip’ a system from one stable state into a profoundly different state."

In 2021, the authors of a study published in the journal Nature wrote that "small changes in forcing cause substantial and irreversible alteration to Earth system components called tipping elements." A 2023 survey published in Sage Journals found members of the British public to be widely demoralized about society's ability to cope with any impending climate change "tipping points." The phrase even appears in the kids' scientific magazine Frontiers for Young Minds, appearing in a 2021 article titled "Tipping Points: Climate Surprises."


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Yet many scientists do not like the term because they feel it oversimplifies the science or because it cultivates a fatalistic outlook. Hansen is among those scientists. The Columbia University climatologist is renowned for writing about fossil fuel consumption and climate change as far back as the 1980s, when few other public figures had done so. Hansen's 1988 testimony before the Senate is widely considered to be a landmark event in the history of spreading public knowledge about Earth's rising temperatures. How we frame that issue is important to how we effectively spread that message.

"The tipping point concept is greatly overused and misused," Hansen wrote to Salon. "The phrase is mighty popular among scientists and the public, used for many different climate processes. In fact, most of those processes are better described as amplifying, reversible, feedbacks." Although climate change is going to have very significant consequences for humanity, "it is not a runaway process."

Kevin Trenberth, a distinguished scholar at the National Center for Atmospheric Research who has published more than 600 articles on climatology agrees, explaining in an email to Salon that "there are no real tipping points. There are times when the rates of change may increase substantially because of feedbacks, but it is not like a pencil balancing on its end that when touched topples over."

Unfortunately, for fans of scientific accuracy, that is precisely how climate change is depicted in famous sci-fi representations of climate change like the 2004 blockbuster "The Day After Tomorrow." Then again, it is difficult to blame popular entertainers for reinforcing that particular misconception. People who learn about how humanity has negatively altered our natural environment can respond with a wide range of negative emotions, including hopelessness and anxiety, and people experiencing those emotions are more likely to believe there is a "tipping point," after which humanity is utterly doomed.

Yet that notion is mistaken. Walt Meier, a senior scientist at the University of Colorado Boulder's National Snow and Ice Data Center, similarly told Salon he does not believe it is scientifically accurate to say "that there is a tipping point toward 'genuine civilization collapse,'" although there are individual irreversible thresholds that humans could pass.

Meier's colleague Julienne C. Stroeve, also a senior scientist at the University of Colorado Boulder's National Snow and Ice Data Center, wrote to Salon that she thinks of a tipping point "as a threshold [that] when crossed causes a system to change its behavior." This is distinct from how the term is often used, namely with the idea that it involves on a global scale "irreversibility, which has to do with the impossibility of returning to its previous state."

For example, Stroeve said "the loss of Arctic sea ice in summer would be a tipping point, but it’s not irreversible." Losing the winter cover ice, by contrast, would be irreversible, but defining such an event depends on the timescale. "On a geological timescale ice sheets have come and gone, but on a human timescale if we lose them we can basically consider them gone forever." The term "forever" means one thing for geologists and glaciologists studying epochs, and quite another to a person who wants to gaze upon ice sheets with their own eyes.

Hansen pointed to melting permafrost as an example for why the framing implied in the phrase "tipping point" is misleading.

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"It is not like a pencil balancing on its end that when touched topples over."

"There is a tremendous store of carbon in permafrost, which, if all released to the atmosphere, would have a devastating climate impact," Hansen said. He explained how the carbon dioxide that is released by melting permafrost amplifies the global warming caused by human-made greenhouse gases, but that would not happen all at once. "It is rather slow and can be cut off if we begin to cool the planet. That's no small task, of course!"

When these scientists question the usefulness of "tipping point" terminology, they are not discounting the genuine threat posed to humanity by global heating. They all agree that climate change is changing the planet in ways that will harm hundreds of millions of people. Yet how we frame these issues is critical to how we start to address them and experts argue that the idea of a single occasion in which humans cross a barrier from "climate change can be fixed" to "climate change is unfixable" is inaccurate. The Earth's climate is far more complicated than such framing suggests. Instead of seeking a single moment when a figurative switch is flipped, people should look for a constellation of warning signs. There are already many signs that the planet's rising temperature is leading to ecological devastation.

"The way we are going we are already on a dangerous course," Trenberth said. "Only in retrospect will we likely say 'Oh, this was a sort of tipping point.'" He listed off variables that could be viewed by future historians as tipping points, but which may not be recognized as such by contemporaries living through them.

People who live near coasts may in retrospect view rapid sea level rise as a tipping point, since they will endure massive floods and coastal erosion. Those who inhabit flat areas like plains will also experience worsened flooding due to climate change, and people in regions all over the planet will be susceptible to the droughts caused by heat waves.

"There is a big chance (natural variability) component to when and where these threats are realized," Trenberth said.

Stroeve said that potential red flags for Earth entering a severe state of crisis would include irreversible loss of ice for the Greenland and West Antarctic ice sheets, which could between 1-3º C and 1-6º C respectively, although Stroeve added "there are lots of uncertainties here." Similarly, Stroeve speculated that there could be a tipping point-like event in the Amazon rainforest if its area shrinks so much that it cannot generate enough water vapor to support itself. Stroeve said she isn't "sure if that would be irreversible, though."

Meier confirmed Stroeve's observation about the potentially catastrophic consequences of rapid loss to those ice sheets.

"The ice sheets won’t suddenly lose all of their ice — it is something that will happen over hundreds and even thousands of years," Meier said. "As climate changes, there will definitely be costs — in money [such as] infrastructure and human lives as we try to mitigate and adapt to climate change. We will have to live with — and already are living with — sea level rise, more extreme weather, more wildfires, ecosystem changes, etc."

That said, it will not lead to a global civilization collapse all at once. Hansen likewise mentioned the possible collapse of the Greenland and West Antarctic ice sheets as events that would signal, if not a "tipping point," at the very least some level of long-term damage to the planet. He also speculated that this could happen if a system of ocean currents known as the Atlantic Meridional Overturning Circulation (AMOC) completely collapses.

"It would take centuries for AMOC to recover. This will not cause civilization to collapse per se, but it could happen as early as mid-century and in doing so speed the collapse of the West Antarctic ice sheet. [This is] because shutting down AMOC reduces the transport of Southern Hemisphere heat to the tropics and into the Northern Hemisphere," Hansen explained. "It is rapid sea level rise and the accompanying shifting of climate zones that create a potential existential threat to humanity, as they would drive emigration pressures that could make the planet ungovernable."

Hansen added that mass extinctions are certainly irreversible, although they may not count as "tipping points" exactly. "Extermination of species is practically irreversible and some ecosystems can collapse if key species go extinct, and we are in the midst of a mass extinction event," Hansen said.

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As he summed it up, the underlying problem in communicating climate change is that events that may seem to unfold slowly to other people are actually happening rapidly in terms of the larger history of Earth.

"The delayed response of the climate system to human-made climate forcing is what makes these issues so difficult to communicate with the public," Hansen said. "The time scales are very slow as seen by the public, even though human-forced climate change is occurring very rapidly compared with geological time scales."


This is why it's misleading to frame the climate change crisis in terms of a climax or tipping point — it establishes false expectations about how exactly global warming is harming everyone's lives. It is instead more useful to view climate change as a multifaceted dilemma that will require an equally multifaceted response. As Meier noted, this still emphasizes that the issue is very difficult to beat — but also established that is not an impossible dilemma.

"I worry about talking about climate change leading to 'civilization collapse' or even human extinction will actually lead to fatalism and the thought that there is nothing society can do, so let’s not worry about it," Meier said. "Climate change it is a big challenge, but a solvable one."

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