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The world is in danger of hitting six interconnected “tipping points” that could have catastrophic impacts on both people and the planet, according to a report by a United Nations think tank. They include mounting space debris, depleting groundwater and the melting of mountain glaciers.
Tipping points are critical thresholds in natural and societal systems that are reached when the system can no longer provide its expected function. Caitlyn Eberle at the United Nations University (UNU) in Germany and her colleagues have identified the key tipping points that connect the physical climate system to society. “We wanted to look at what point all these physical changes will lead to people experiencing this risky future,” says Eberle.
The first is species extinctions, which are being accelerated by human activities and now occur at more than 10 times the natural rate. If too many species are wiped out in quick succession, it could trigger even more extinctions and lead to ecosystem collapses.
Many people rely on underground water reservoirs for drinking and agriculture. If this groundwater is depleted quicker than it is naturally replenished, then food production could be seriously hindered.
The meltwater from mountain glaciers is another vital source of water. Once glaciers reach what is known as “peak water”, which is when they provide the maximum amount of water run-off, then the supply will slowly decline. In many glaciers around the world, including ones in Europe and South America, this threshold has already been passed.
Around 75 per cent of all the monitored objects in Earth’s orbit are junk. If the planet’s orbit gets too crowded with this space debris, that will lead to collisions that could destroy satellites.
“If we lose these eyes in the sky, we lose that ability to better monitor things like biodiversity or weather,” says team member Jack O’Connor at the UNU.
Temperature records have been smashed across the planet in recent years, with heatwaves becoming increasingly commonplace. With further warming, we are likely to see heatwaves so intense that even healthy young people could die.
The last tipping point is when it gets too costly for most people to insure their property against extreme weather events or natural disasters. By 2030, it is predicted that over 500,000 homes in Australia will be too expensive to insure due to flooding risks.
Some of these tipping points have already been crossed, says Eberle: groundwater has been depleted in parts of Saudi Arabia and extreme temperatures near the limits of human survivability have been observed in Asia.
“To avoid these tipping points, we need to move towards what we call transformation and really change the system,” says O’Connor. For instance, “we need to start considering the risk of rising heat in how we build our cities”.
“All of these things are caused by those human behaviours and acts and values,” says Eberle. “We have the power to sort of shift our mindsets. This transformation needs to be on an individual level right the way up to governments.”
“Considering how shocks can originate and spread through socio-ecological networks is an important and under-researched field, to which this report is a welcome contribution,” says David Armstrong McKay at the University of Exeter, UK. “While the issues highlighted by this report are important, not all of them feature this critical self-sustaining tipping dynamic and framing all of them as ‘risk tipping points’ risks further confusion on what we mean by tipping points.”
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