These five tipping points could massively exacerbate the crisis

Report on climate change - These five tipping points could massively exacerbate the crisis

The frog in the cooking pot is a much-used metaphor for mankind's approach to global warming. If the pot is heated very gradually, so the legend goes, the frog hardly notices for a long time. Until the deadly overheating makes it impossible for it to hop out of the pot. This is an exaggerated image of climate change, which also appears to be happening slowly and will eventually have dramatic effects.

Some of these consequences could even develop a self-reinforcing dynamic: Many elements of the earth and climate system are considered by experts to be so critical and unstable that they could "tip over" relatively quickly under certain circumstances and trigger real domino effects in the climate system - with far-reaching and possibly irreversible consequences for ecosystems and humanity.

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The recently published "Global Tipping Points Report" lists these neuralgic "tipping points" ("tipping elements"). More than 200 researchers from 26 countries worked on the report under the leadership of the British University of Exeter; the large-scale project was co-financed by the "Bezos Earth Fund" of Amazon founder Jeff Bezos. The report is probably the most comprehensive analysis of tipping points to date.

Like a snowball that triggers an avalanche

The danger with tipping points is that they are not only self-reinforcing, but can also interact with each other, accelerating and fueling each other, as if a snowball were slowly rolling over the edge of a slope, picking up more and more speed, taking more snow with it and at some point triggering an avalanche.

25 tipping elements in the Earth system are named in the report. Five of these could already tip at the current level of global warming. The reefs could be hit the fastest, namely within a few years: "Even today, at 1.2 degrees of global warming, it is likely that coral reefs in the tropics will tip over," explains Jonathan Donges from the Potsdam Institute for Climate Impact Research (PIK), one of the lead authors of the report, in a press briefing by the Science Media Center Germany.

If global warming reaches an average of 1.5 degrees - which would still be in line with the goals of the Paris Climate Agreement - a large proportion of coral reefs could die off completely. At 1.5 degrees, the large coniferous forests of the north, tropical mangroves on the coasts and seagrass meadows in the oceans would also be destabilized and possibly damaged forever, the authors conclude. From around 2 degrees, the Amazon rainforest would also be on the brink of collapse and large parts of the Antarctic ice sheet could thaw.

500 million people would be exposed to flooding

The consequences would be catastrophic: a melting of the Antarctic ice sheet could lead to a sea level rise of two meters within this century, which would expose around 500 million people on the coasts to regular flooding events. Changes in the major ocean currents in the Atlantic could change the weather in Europe, leading to more droughts and crop failures.

Social tipping points also loom: according to the report, the dramatic consequences of climate change also harbour the risk of societies becoming polarized and radicalized, mental illnesses increasing or violent conflicts breaking out. On the other hand, positive tipping points can also be triggered in the social sphere: climate-friendly technologies and behaviors that spread faster and faster after a certain point and help to reduce greenhouse gas emissions, for example

"Social tipping points can follow similar patterns to earth system tipping points, so there can also be cascades or domino effects," says Caroline Zimm from the International Institute for Applied Systems Analysis in Laxenburg, Austria. Zimm is the lead author of the chapter on social and positive tipping points.

Positive example of electromobility

According to the report, renewable energies have reached their tipping point because they have become increasingly cost-efficient and in some cases are already cheaper than oil, gas or coal - the most important prerequisite for their further spread. Another example of a positive domino effect is electromobility, according to Zimm. As it becomes more widespread, there is greater demand and more innovations in battery research. "This reduces costs and is not only relevant for e-mobility, but also for renewable energies and their storage." Wind farms, for example, are also dependent on efficient and compact storage technology in order to "temporarily store" the electricity generated for low-wind weather conditions.

However, such positive tipping effects do not arise "out of thin air", says Zimm, but as a result of political decisions. A current example of this is the breakthrough of electromobility in Norway. Since the 1990s, the Norwegian government has been providing targeted incentives for the purchase of electric cars: it lowered VAT on electric vehicles, subsidized their purchase and built up a well-functioning charging infrastructure over the years. Between 2015 and 2022 alone, the number of publicly accessible charging stations across the country grew by more than 300 percent to more than 24,000.

It took until 2016 for the e-mobility market in Norway to pick up significantly. But then it really exploded. There are still far more combustion cars on Norway's roads than electric cars. But by the end of 2022, the share of e-cars among new cars was an impressive 80 percent, compared to only around 25 percent in Germany. Norway is currently experiencing a classic domino effect, triggered by consistent political decisions.

The concept of tipping points is not uncontroversial

However, the authors of the Global Report concede that many research questions remain unanswered, particularly with regard to social tipping points and their feedback effects with climate change. The general concept of tipping points is also not uncontroversial. At present, it is not possible to predict with certainty when complex systems such as the Amazon or the Antarctic ice will actually start to change more rapidly and to what extent this is actually irreversible.

Gerrit Lohmann conducts research at the Alfred Wegener Institute/Helmholtz Center for Polar and Marine Research in Bremerhaven and was not involved in the current report. In addition to the many uncertainties surrounding the definition of specific tipping points, he is also critical of its completely forward-looking approach: "I find the concept helpful in understanding long-term stability effects. But on the other hand, the concept suggests that you are safe if you are below certain thresholds".

However, especially with regard to extreme weather, such as drought or flooding like in the Ahr valley, we have to counter this: "We are actually already in the middle of climate change. And extreme weather events are increasing, even though we haven't yet experienced such serious changes as the loss of the Antarctic ice sheet." Care must therefore be taken when communicating tipping points "to avoid giving the impression that we are on a safe path below 2 degrees."