A tipping point in the Earth’s climate system is a threshold that, when exceeded, can lead to large changes in the state of the system. Potential tipping points were identified in the physical climate system, in impacted ecosystems, and sometimes in both at least a decade ago.
The problem facing the world today is something called “cascading tipping points.” This is where one part of the climate system reached a threshold that triggers another element in the system, creating a new state of crisis. For example, the melting of ice sheets in Greenland and Antarctica will significantly alter ocean circulation.
Taking into consideration that weather events can sometimes disturb the climate systems – after the disruption, the system can be expected to move back into equilibrium. As an example, a storm may damage sea ice, which grows back after the storm has passed. However, if that system is getting close to a “tipping point,” it will take longer to reach a normal state.
Monitoring and recording changes in the various climate systems can give scientists valuable data on the health of those systems and how far they are tipping to the point of no return.
Climate tipping points are too risky to ignore
In an article published in the journal Nature, a group of scientists with Exeter University writes there is growing evidence to suggest that irreversible changes to the Earth’s environmental systems are already taking place and that we are now in a “state of planetary emergency.”
This “cascade” of changes sparked by global warming could threaten the existence of human civilizations. “A decade ago we identified a suite of potential tipping points in the Earth system, now we see evidence that over half of them have been activated,” said lead author Professor Tim Lenton, director of the Global Systems Institute at the University of Exeter.
Professor Lenton says the situation is now urgent, and so much so that “we need an emergency response.” Co-author Johan Rockström, director of the Potsdam Institute for Climate Impact Research, said: “It is not only human pressures on Earth that continue rising to unprecedented levels,” reports Science Daily.
“It is also that as science advances, we must admit that we have underestimated the risks of unleashing irreversible changes, where the planet self-amplifies global warming. This is what we now start seeing, already at 1°C global warming.”
Nine active tipping points
Exiting the fossil fuel economy is unlikely before 2050, but with the temperature already at 1.1°C above pre-industrial temperature, it is likely Earth will cross the 1.5°C guardrail by 2040. The authors conclude this alone defines an emergency.
The researchers have identified nine active tipping points – of which over half of them has now been activated. They include:
1. Arctic sea ice
2. Greenland ice sheet
3. Boreal forests
4. Permafrost
5. Atlantic Meridional Overturning Circulation
6. Amazon rainforest
7. Warm-water corals
8. West Antarctic Ice Sheet
9. Parts of East Antarctica
The loss of Arctic sea ice and the collapse of major ice sheets on Greenland, West Antarctica and part of East Antarctica will result in sea levels rising 10 meters (32.8 feet). Reducing greenhouse gas emissions could at least give us time to move away from coastlines.
Rainforests, boreal forests and the permafrost are all examples of biosphere tipping points that if crossed – will result in the release of additional GHGs effectively amplifying warming.
While it is difficult to predict what system will tip next, the scientists argue: “If damaging tipping cascades can occur and a global tipping cannot be ruled out, then this is an existential threat to civilization. No amount of economic cost-benefit analysis is going to help us. We need to change our approach to the climate problem.”
Professor Lenton added: “We might already have crossed the threshold for a cascade of inter-related tipping points. “However, the rate at which they progress, and therefore the risk they pose, can be reduced by cutting our emissions.”
