What’s the worst that could happen? This is a question that engineers, for example, ask themselves quite often – this planning is part of their job. That is why many nuclear power plants today are also designed to withstand plane crashes and earthquakes. Even if such events are unlikely to occur, the damage would simply be too great to ignore in good conscience.
With regard to climate change, however, such “worst-case scenarios” have hardly been researched, numerous climate researchers complained in one this week Opinion article in the journal PNAS. A serious omission, write the authors around Luke Kemp from the University of Cambridge. After all, there are indications that global warming of more than three degrees could have catastrophic consequences for ecosystems and humans – from mass extinction in the oceans to the collapse of states and wars over scarce resources. My colleague Benjamin von Brackel reported extensively on the study here.
What to make of this bleak vision of the future? It would be a misunderstanding to see it as just another reminder of the dangerous consequences of global warming. Rather, the authors’ call for systematic research is central: “Prudent risk management requires that we thoroughly investigate worst-case scenarios.” Where are human societies particularly vulnerable to climate risks? At what point could global warming lead to mass extinction, including human extinction? What does higher CO₂ mean for life on earth in the long term? To what extent can reaching tipping points such as Arctic permafrost thawing further accelerate climate change? These and other questions urgently need to be answered, possibly even in a special report by the Intergovernmental Panel on Climate Change on “catastrophic climate change”.
It can hardly be denied that the more extreme the climate scenario under consideration, the fewer and fewer publications are. Most studies on the consequences of global warming deal with a world warming by 1.5 or 2 degrees or slightly more. Beyond 3 or 4 degrees, the air gets thin, and the effects on food supplies in this temperature range would be catastrophic. And there are very few studies on an almost apocalyptic 6-degree future, British science journalist Mark Lynas complains in the book “Our Final Warning”, in which he evaluates the current state of knowledge on the consequences of different temperature scenarios. “The reason for this rather unusual omission could be that climatologists are human beings and as scientists prefer not to think about worst-case scenarios,” writes Lynas. Or they didn’t want to be seen as “alarmists” and “doomsayers”.
According to the current state of knowledge, a warming of 6 degrees would require emissions to continue to rise practically unchecked, which is rather unlikely. However, the probability is significantly higher than a plane crash, argues Lynas – and investments are constantly being made in preventing such accidents in order to reduce the risk even further. “But in the case of the planet, we are all on board together and have no choice.”
Knowing the worst possible future, on the other hand, can encourage action, according to the authors of the current PNAS paper. In the 1980s, for example, the realization that nuclear war could lead to a “nuclear winter” led to more efforts for disarmament and peace.
Personally, I think both are needed: on the one hand, more knowledge about what threatens the world if climate change is unbridled. On the other hand, there are also positive counter-proposals, utopias that show how the quality of life can be improved if global warming is kept as low as possible.
(This text is from the weekly Newsletter climate friday you here for free can order.)