Is Climate Overshoot the New Tipping Points?

We need ambitious climate action, because … — The second part of this sentence will most likely contain some reference to tipping points. 

Negative tipping points refer to large-scale planetary systems that can tip into a different state due to climate change and cause irreversible harm to societies. 

Why is this framing so popular? 

1. Irreversibility: Some things that we care about (e.g., ice sheets, rainforests) might be lost forever and would not come back even if global temperatures decreased again.
2. Urgency: Tipping points drive home the message that “it might be too late” after a certain level of warming. 

Too late for what?

This message of urgency and irreversibility has been developed as a “justification [for] binding temperature targets” (Lenton et al., 2008), and it is central to a lot of climate communication efforts.

But the concept of tipping points has its problems (see Kopp et al., 2024). People worry about the fuzziness of its definition, about the lack of scientific consensus around specific tipping points, and about the fear of tipping points leading to fatalism (…once we reach the tipping points, we are doomed anyway – why still care about mitigation?).

This is where climate overshoot comes in. Overshoot means that the Earth temporarily exceeds a temperature target, say the 1.5°C target of global warming, but returns to below this temperature level later in the century.

Many recent overshoot papers show that:

1. The world after overshoot would be worse than the world before it. That means, some things are irreversibly lost in the process of overshooting—AKA “overshoot legacy” (de Vrese & Brovkin, 2021).
2. The only way to avoid these consequences is through “stringent and immediate emissions reductions” (Schleussner et al., 2024).

These echo the two main communicative elements of the tipping points framing: irreversibility and urgency. So, is overshoot the new tipping points? 

It can surely fulfill some of the same functions for climate communicators. But to be fair, it does avoid some of the problems that come with the tipping points concept:

• Overshoot does not have to assume the existence of a certain physical threshold in the climate system. The overshot target is given by the Paris Agreement (2015), which saves a lot of arguing about whether there is a specific threshold at all.
• Overshoot does not lend itself so well to fatalism. After overshooting 1.5°C, some things are irreversibly lost – but there is no doubt that returning to 1.5°C is preferable to staying at higher temperature levels. In the overshoot framing, mitigation is always worthwhile – it is just worth more when conducted early.
• Overshoot is not restricted to certain well-defined tipping elements. One can estimate the overshoot legacy of anything we care about without having to argue whether a certain Earth subsystem fulfills the criteria for being a tipping element (or even which criteria to choose).

Will “overshoot” replace the tipping points framing in the coming years? Unlikely; Tipping points are so deeply engrained in the rhetorical fabric of climate communication. But it seems that some climate researchers are attempting to avoid the rhetoric of tipping points by taking refuge in the more solidly defined concept of climate overshoot.

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