A much-used metaphor for how humanity deals with global warming is the frog in the cooking pot. Legend has it that if the pot is heated very gradually, the frog will hardly notice it for a long time. Until at some point the fatal overheating made it impossible for him to hop out of the tub. A pointed picture of climate change, which also appears to occur slowly and at some point has 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 and trigger real domino effects in the climate system - with far-reaching and possibly irreversible consequences for ecosystems and humanity.
The recently published “GlobalTippingPoints Report” lists these critical “tipping points”, also called tipping elements. Under the leadership of the British University of Exeter, more than 200 researchers from 26 countries worked on it; the large-scale project was co-financed by the “Bezos Earth Fund” run by Amazon founder Jeff Bezos. The report is probably the most comprehensive analysis of tipping points to date.
The danger with tipping points is that they not only reinforce themselves, 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, gaining more and more speed, dragging more snow with it and eventually a snowball Trigger an avalanche.
25 tipping elements in the Earth system are named in the report. Five of them could collapse at the current level of global warming. It could hit the reefs most quickly, namely within a few years: "Even today, with 1.2 degrees of global warming, it is likely that coral reefs in the tropics will collapse," 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 even be in line with the goals of the Paris Climate Agreement - a large part of the 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 and large parts of the Antarctic ice sheet could thaw.
The consequences would be catastrophic: 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 major ocean currents in the Atlantic could disrupt the weather in Europe and lead to more droughts and crop failures.
Social tipping points are also looming: According to the report, the dramatic consequences of climate change also pose the risk that societies will polarize and radicalize, that mental illness will increase or that violent conflicts will break out. However, on the other hand, positive tipping effects can also be triggered, especially in the social sector: climate-friendly technologies and behaviors that spread ever faster after a certain point and that help, for example, to reduce greenhouse gas emissions
“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 lead author of the chapter on social and positive tipping points.
According to the report, renewable energies have reached their tipping point because they have become increasingly cost-efficient and are sometimes already cheaper than oil, gas or coal - the most important prerequisite for their further widespread use. Another example of a positive domino effect is electromobility, says Zimm. As they become more widespread, there is greater demand and more innovation in battery research. "This reduces costs and is relevant not only for e-mobility, but also for renewable energies and their storage." Wind farms, for example, also rely 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 rather as a result of political decisions. A current example of this is the breakthrough in electromobility in Norway. Since the 1990s, the Norwegian government has been providing targeted incentives for the purchase of e-cars: it reduced the VAT on e-mobiles, 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 points across the country grew by more than 300 percent to more than 24,000.
It took until 2016 for the electric vehicle market in Norway to pick up significantly. But then he literally exploded. There are still many more combustion engines than electric cars on Norway's roads. But at the end of 2022, the share of electric cars in new cars was an impressive 80 percent, while in Germany it was only around 25 percent. Norway is currently experiencing a classic domino effect, triggered by consistent political decisions.
However, the authors of the Global Report admit that many research questions remain unanswered, particularly when it comes to social tipping effects and their feedback from climate change. The general concept of tipping points is also not without controversy. It is currently not possible to predict with certainty when complex systems such as the Amazon or the Antarctic ice will begin to change more and more rapidly and to what extent this will actually be irreversible.
Gerrit Lohmann researches 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 in defining concrete tipping points, he is also critical of their completely future-oriented approach: "I find the concept helpful in understanding long-term stability effects. But on the other hand, the concept suggests that one lives in security "if you are below certain threshold values".
But especially when it comes to extreme weather, such as drought or floods like in the Ahr Valley, one has to counter this: "We are actually already in the middle of climate change. And the extreme weather events are increasing, even though we have not yet experienced any changes as serious as the loss of the Antarctic ice cap." One must therefore be careful when communicating tipping points "so that the impression does not arise that we are on a safe path below 2 degrees."