Tipping points: Turning a bad situation into something much worse
An explanation from our resident climate scientist, Neil Plummer
Climate scientists have been concerned about tipping points for decades and for good reason – they have the potential to turn a bad situation into something much worse!
Some climate scientists have said that “we are already deep into the trajectory towards collapse” of civilisation, which may now be inevitable because 9 of the 15 known global climate tipping points that regulate the state of the planet have been activated  .
Tipping points arise because the Earth’s climate system is highly non-linear, where inputs and outputs are not proportional, change is often abrupt, rather than slow and gradual, and where the climate has the potential to shift between multiple different stable states.
Our climate system is highly complex and consists of five major components: the atmosphere, the hydrosphere (water), the cryosphere (ice and permafrost), the lithosphere (earth's upper rocky layer), the biosphere (living things) and the interactions between them. The climate system evolves in time under the influence of its own internal dynamics and because of external factors such as volcanic eruptions, solar variations and anthropogenic (human) factors such as the changing composition of the atmosphere (e.g. increasing greenhouse gases) and land-use change (e.g. deforestation).
Climate models provide very useful future projections of temperature, rainfall, winds, ocean currents and other elements within our climate system. However, they are limited in their capability to predict the precise timing, location and magnitude of abrupt climate shifts with reasonable confidence.
So, in being highly non-linear, our climate is vulnerable to tipping points with the potential for changes so large and rapid that the very best adaptation plans can be worthless in an environment dominated by high uncertainties and many unknowns.
Climate scientists are ‘systems thinkers’; prodding one component of the climate system, e.g. burning fossil fuels and increasing atmospheric carbon dioxide concentrations, will have impacts on other components, e.g. warming the oceans and melting ice sheets and sea-ice which, in turn, will cause changes in other components. You can see how small changes can easily magnify.
For a nice visual explanation of four of the key components of the climate system, watch the video below:
What are tipping points?
The Intergovernmental Panel on Climate Change (IPCC) is always a good source for climate definitions and its recently published special report on the impacts of global warming of 1.5 °C above pre-industrial levels is as good as anywhere.
Sybren Drijfhout describes one of the more simple examples, “Because seawater reflects less sunlight than ice – and absorbs more heat – disappearing sea ice means further local warming, which in turn means more melting sea ice. This process may quickly amplify the effect of global warming. Most climate models simulate an abrupt disappearance of all summer sea-ice in the Arctic at some point this century.”
A short introduction to tipping points is given in this video:
What did Malcom Gladwell have to say about tipping points?
It might seem odd to bring up the work of a best-selling author and thinker in a science article but Gladwell did write a great book on tipping points. While he mostly covered trends in business, marketing and human behaviour, and not about tips in the climate system, there are definitely some interesting parallels.
As with the IPCC definition above, I’m sure you can think of several examples in history where a way of doing things suddenly shifted to a very different way of doing things, i.e. from one stable state to another stable state, and did not return to the initial state even when the drivers of the change were abated.
According to Gladwell, the tipping point is "that magic moment when an idea, trend, or social behaviour crosses a threshold, tips, and spreads like wildfire”. Key to activating a tipping point are having:
- People who significantly Influence change through their expertise, connections or ability to ‘sell’ an idea
- A stickiness factor which causes the phenomenon to "stick" in the minds of the public and influence their behaviour, and
- The power of context, which refers to the environment or historical moment in which the trend is introduced.
Interestingly, and more relevant to climate, is whether we are witnessing a tipping point with regard to climate action as a consequence of the first three months of 2020. Let’s run this through the criteria:
- Fire experts, climate scientists and health experts increasing their influence through credible science and predictions on the summer bushfires and impacts of COVID-19
- The tragic deaths, economic disruption and environmental damage sticking in the minds of the public and resulting in changes in attitudes and behaviours, and
- COVID-19 and climate change amplifying inequalities for millions of people who are now questioning whether the dominant political and economic systems of the last 40 years are the most suitable for society.
It is still too early to tell on whether we are living through a major societal tipping point but, according to Gladwell’s criteria, early 2020 has undoubtedly seen the greatest disruption for many people alive today.
Back to the science …
What are the key climate tipping points?
The IPCC 1.5 report discussed those parts of the climate that are thought to hold the risk of reaching critical tipping points under climate change, and that can result in or be associated with major shifts in the climate system. These components include the:
- West Antarctic ice sheet, Greenland ice sheet: evidence suggests that the temperature range of 1.5°C to 2°C may be regarded as representing moderate risk, in that it may trigger ice instabilities in Antarctica or irreversible loss of the Greenland ice sheet. Further, these may be associated with sea-level rise by as much as 1 to 2 metres over a period of two centuries.
- Slowdown of the Atlantic Meridional Overturning Circulation (AMOC): Weakening of AMOC is projected to be highly disruptive to natural and human systems as the delivery of heat to higher latitudes via this current system is reduced. While it is very likely that the AMOC will weaken over the 21st century there is, at present, no evidence indicating a shutdown of the AMOC at 1.5°C to 2°C thresholds.
- El Niño events: these are associated with large-scale drought and higher temperatures over Australia. Recent research indicates that the frequency of extreme El Niño events increases linearly with the global mean temperature, and that the number of such events might double under 1.5°C of global warming. This pattern is projected to persist for a century after stabilisation at 1.5°C, thereby challenging the limits to adaptation, and thus indicating high risks even at the 1.5°C threshold.
- Role of the Southern Ocean in the global carbon cycle: The critical role of the Southern Ocean as a net sink of carbon might decline under global warming. If warmer oceans are less effective in absorbing carbon then atmospheric concentrations will rise further. Moderate risk is now located at 1°C of warming and high risk is located at 2.5°C.
Timothy Lenton and colleagues explore these and other potential tipping points in more detail and these include:
- 99% of tropical corals are projected to be lost if global average temperature rises by 2°C, owing to interactions between warming, ocean acidification and pollution.
- Deforestation and climate change are destabilising the Amazon, which is home to one in ten known species. Estimates of where an Amazon tipping point (triggering irreversible decline) could lie range from 40% deforestation to just 20% forest-cover loss. About 17% has been lost since 1970.
- Frozen soils are starting to thaw in Arctic regions and often for the first time in thousands of years. Additional releases of carbon dioxide and methane to the atmosphere will make constraining atmospheric carbon dioxide concentrations much more difficult.
Increasing atmospheric greenhouse gases are increasing risks to the economy, environment and society and, as these concentrations rise, the risks of reaching tipping points and irreversible changes also increases.
Climate scientists’ Rachel Warren and Sally Brown make this clear: “Limiting warming to 1.5°C will save the global economy trillions of dollars in the long run, even accounting for the seemingly gargantuan cost of transitioning our energy systems. But this is more than just an economic or academic issue – it’s a matter of life and death for millions of humans and animal species, and a severe threat to the well-being of billions.”
Turning a bad situation into something much worse must be avoided. Pretending climate change isn’t happening, or looking the other way, has never been ethical nor acceptable. Now it is unambiguously irresponsible and dangerous.