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Effects & Impacts: Climate tipping points

June 2019 the ice sheet near Qaanaaq Greenland that they would normally sled across was covered in vast meltwater lakes due to extreme surface warming (17°C). Meltwater eventually drains into the ocean, contributing to rising sea levels and disrupting oceanic currents. – Video: Steffen M. Olsen, Danish Meteorological Institute.

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Climate tipping points

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Summary

Harmful tipping points in the natural world pose some of the gravest threats faced by humanity. Their triggering will severely damage our planet’s life-support systems and threaten the stability of our societies. – Global Tipping Points Report, 2023

It’s like someone leaning back in a chair. If they don’t tilt too far, they can easily return to having all four legs on the floor. But once they pass the tipping point, the whole system comes crashing down. And it is much harder to get up again than it was to fall. – Mathematician Niklas Boers, Carbon Brief

Everything in the Earth system is connected. When one part of the climate system crosses its tipping point, then that might make it more likely for other parts of the system to also cross their critical thresholds. So you can think of this in terms of dominoes. If you tip one of them over, then this might lead to cascading effect. – Prof. Jason Box in Breaking Boundaries: The Science of our Planet.

Whether we will have any warnings of climate tipping points is one of the biggest concerns of climate scientists today. As we pass global warming of 1.5˚C, the most likely tipping points involve the collapse of ice sheets in Greenland or Antarctica, tropical coral reefs dying off, or abrupt thawing of Arctic permafrost.
 
One of the big questions is whether tipping points will be characterised by flickering or whether the climate will initially appear to become more stable before tipping over in one go. – Trauth et al, May, 2024
 
  • Tipping points are often non-linear and self-perpetuating (Fig. 1). That is:

(1) they generally happen abruptly rather than gradually, and with little to no warning

(2) they are irreversible in human time-frames

(3) there is no way to control them

(4) some will trigger massive carbon emissions from what once were natural carbon sinks, such as the Amazon rainforest, which in 2021 stopped being a carbon sink (Video 5); permafrost; the loss of 28% of the Earth’s entire tropical peat stocks; and carbon in other soils (which are not accounted for in climate models) now on the move.

(5) they threaten the natural world and us

  • Key tipping points recognised by the IPCC but not factored into projections, are now being breached (Video 2).

  Effects

Other sections

Home > Climate wiki > Effects > Tipping points

Summary

Harmful tipping points in the natural world pose some of the gravest threats faced by humanity. Their triggering will severely damage our planet’s life-support systems and threaten the stability of our societies. – Global Tipping Points Report, 2023

It’s like someone leaning back in a chair. If they don’t tilt too far, they can easily return to having all four legs on the floor. But once they pass the tipping point, the whole system comes crashing down. And it is much harder to get up again than it was to fall. – Mathematician Niklas Boers, Carbon Brief

Everything in the Earth system is connected. When one part of the climate system crosses its tipping point, then that might make it more likely for other parts of the system to also cross their critical thresholds. So you can think of this in terms of dominoes. If you tip one of them over, then this might lead to cascading effect. – Prof. Jason Box in Breaking Boundaries: The Science of our Planet.

Whether we will have any warnings of climate tipping points is one of the biggest concerns of climate scientists today. As we pass global warming of 1.5˚C, the most likely tipping points involve the collapse of ice sheets in Greenland or Antarctica, tropical coral reefs dying off, or abrupt thawing of Arctic permafrost.
 
One of the big questions is whether tipping points will be characterised by flickering or whether the climate will initially appear to become more stable before tipping over in one go. – Trauth et al, May, 2024
 
  • Tipping points are often non-linear and self-perpetuating (Fig. 1). That is:

(1) they generally happen abruptly rather than gradually, and with little to no warning

(2) they are irreversible in human time-frames

(3) there is no way to control them

(4) some will trigger massive carbon emissions from what once were natural carbon sinks, such as the Amazon rainforest, which in 2021 stopped being a carbon sink (Video 5); permafrost; the loss of 28% of the Earth’s entire tropical peat stocks; and carbon in other soils (which are not accounted for in climate models) now on the move.

(5) they threaten the natural world and us

  • Key tipping points recognised by the IPCC but not factored into projections, are now being breached (Video 2).

Tipping points are when we push so called tipping elements across their biophysical thresholds which leads to an irreversible change. A tipping element is a biophysical system that fulfills 2 criteria:

  • Scientific evidence that it contributes to regulate the state of the climate system.
  • Scientific evidence of multiple stable states, for example, either frozen ice sheet or liquefied ice. Another example is either a rainforest or savannah.

What separates these states are the interactions and feedbacks between non-negotiable biological chemical physical properties such as the melting point of ice. For example, a healthy ice sheet with very high altitude that’s very cold. If that starts melting, it gets lower and lower altitude, so you get a self-amplifying feedback, because the lower the altitude, the warmer it gets, and the darker the surface—because it is liquefied—the albedo shifts from reflecting to absorbing yet more heat.  – Prof. Johan Rockstron (Video 2)

Human generated greenhouse gas emissions and biodiversity loss—over which we do have control but are failing to do so—are passing critical thresholds, tipping the climate into a state that we humans have never before experienced.

Governments agreed that to ‘avoid a critical threshold above which the planet could experience irreversible catastrophic impacts‘, global temperatures must not exceed 1.5°C above pre-industrial levels  while acknowledging that major tipping points could be reached between 1°C – 2°C. In 2024, average global temperatures exceeded 1.5°C.

The implications are so complex and widespread that only those with immediate and dangerous impacts for Aotearoa New Zealand are covered in this website: biodiversity loss in Aotearoa and the melting cryosphere (Greenland, West Antarctic Ice Shelf, catastrophic decline in Antarctic sea ice, and ocean currents). Links to more information on other tipping points are below. For more detailed information see the website Global Tipping Points.
 Video 1:  Prof. Johan Rockström offers the most       up-to-date scientific assessment of the state of the planet and explains what       must be done to preserve Earth’s resilience to human pressure. (Aug. 2024)  
 Video 2: The science behind planetary boundaries and highlights the urgent   need for transformative change (August 2024). 
 Video 3: Dr Tim Naish from Wellington University explains what Antarctic    climate scientists are finding out and why they are so concerned. Not only will sea levels rise faster this century, but if the West Antarctic Ice Sheet is destabilized, the process could be continuous and irreversible for centuries.
Fig. 1 Tipping points and the temperatures at which they are likely to to (Image: McKay et. al, Science, 9 Sept, 2022)
Fig. 1 Tipping points and the temperatures at which they are likely to to (Image: McKay et. al, Science, 9 Sept, 2022)

Tipping points shown in Fig. 1 have global physical, economic, and social impacts outside the scope of this website. For more detailed  information see Carbon Brief’s website and this 2023 comprehensive paper (if this is inaccessible, download the pre-published PDF: ‘Mechanisms and impacts of climate tipping elements‘).

We may be able to prevent some tipping points if we can reverse rising temperatures by drawing down excessive carbon from the atmosphere. The fastest and most cost-effective way to achieve this is by restoring natural ecosystems, which will bring the collateral benefits of healthy ecosystem services as well as a livable climate.

One of the characteristics of tipping points is that once a system has been tipped into a new state, it can’t be returned to its original state simply by undoing the even that caused it to tip. For example, once global average temperatures pass 2°C, according to the IPCC ocean acidification will persist for tens of thousands of years. Even now there is no practical way to reverse ocean acidification.

Fig. 2 Tipping points and the temperatures at which they are likely to to (Image: Nature, 2023)
Fig. 2 Tipping points and the temperatures at which they are likely to to (Image: Nature, 2023)

Observations from across the Amazon suggest that CO2-driven accelerations of tree growth may have contributed to increasing tree mortality rates (trees grow faster but also die earlier), which could eventually neutralize the forest carbon sink in the coming decades. – Flores et al, 2024

Another example is the south-east Amazonian rainforest, which now appears to have reached a point where plants return more CO2 into the atmosphere than they absorb (Fig. 2). The South American monsoon is at risk of collapsing.
 
Losing biodiversity coupled with current warming globally has already ‘tipped’ heavily forested regions from being carbon sinks into carbon sources. 

If similar temperatures occur over the next few years, it may not be possible for forests to recover; they will have tipped into a new state, one that does not support their future existence. For example, in 2023 widespread wildfires were so extreme that new forests are now unlikely to regrow.
 Video 4: The Amazon rainforest may have passed the tipping point that will flip  it into a savannah.

The only reason why the IPCC provides the world with the remaining carbon budget of roughly 4 – 500 gigatonnes, is that the models assume that the carbon sink capacity of intact nature will continue. So not only are we assuming that biological systems will not cross tipping points, we’re also assuming that the stocks of carbon in forests in soils, in wetlands and permafrost, remain reasonably intact over the next 50 years. That is quite an optimistic assumption because it means we need to invest in conserving the remaining intact ecosystems. – Prof. Johan Rockström, COP 26 (Video 2).

In 2024 researchers found that the Arctic ocean was no longer absorbing as much CO2 because of melting permafrost:
  Video 5: COP26 – Emerging climate risks.

We find that coastal erosion reduces the Arctic Ocean CO2 uptake from the atmosphere in all simulations: by 4.6–13.2 TgC yr−1 by 2100, which is ~7–14% of the Inner Arctic Ocean uptake. We show that coastal permafrost erosion exerts a positive biogeochemical feedback on climate, increasing atmospheric CO2 by 1–2 TgC yr−1 per °C of increase in global surface air temperature. – Neilsen et al


Tipping points covered in more depth on this website: 

Biodiversity loss Aotearoa:

Threats are from introduced pest plants and animals that thrive in a changing climate, ongoing agricultural expansion, pollutants entering waterways, demands for reliable water for irrigation, bulldozing marine ecosystems through bottom trawling, and an Emissions Trading Scheme that financially incentivises monoculture radiata pine plantations over the protection and restoration of biodiverse native ecosystems.

Once tipping points for some native ecosystems and species are reached, the ecosystem services they provided (including flood mitigation, coastal defenses against rising sea levels, and long term carbon sequestration) are, along with many endangered species, gone forever.

Since 2012…over a hundred thousand hectares of true land-use change [has been] going on around wetlands, scrub being cleared, and dairy land-use intensification. – Landcare Research, 2020

Even the most egregious offences—including a dam built on a wetland, clearance of a nationally endangered form of kānuka, and aerial poisoning of swathes of regenerating native bush—often prompted little more than a warning from authorities. – Charlie Mitchell, Stuff, 2020

Fig. 5: Tree cover loss New Zealand 2001-2023 (image: Global Forest Watch)
Fig. 5: Tree cover loss New Zealand 2001-2023 (image: Global Forest Watch)

The melting cryosphere:

The Arctic is melting 4 times faster than the rest of the planet, and up to 7 times faster in the Berring Sea. Melting glaciers, Greenland, and Antarctica, and the rapid decline of sea ice formation in Antarctica and the Arctic is also well underway. This is accelerating sea level rise, changes in and collapse of ocean currents, more extreme weather events, loss of critical ecosystem services (biodiversity), social and economic impacts. Moreover, millennia-old carbon storage systems once regarded as stable—permafrost and clathrates—are disgorging vast quantities of greenhouse gases, which means the remaining IPCC carbon budget is already over-drawn.
 
In Antarctica, Thwaites Glacier is close to collapsing (see also Video 3). Modelling indicates that the loss of the West Antarctic Ice Shelf (WAIS) is now unavoidable, even if emissions are stabilised.

Having two caps of a permanent ice in the Arctic and Antarctica is the very precondition for the planet to stay in a state that has enabled us to develop civilizations as we know it. Whether it’s a small glacier or whether we’re talking about Greenland, they all add together to this fantastic capacity of cooling the planet.

Icecaps and glaciers are reflecting back 90 to 95% of incoming heat from the sun. When these ice sheets start melting, you can come to a point where the ice sheets tip over from being self-cooling to becoming self-warming and that is the most dramatic tipping point in their system..in the current climate, Greenland is already beyond its threshold where it’s now losing 10,000 cubic metres of ice per second. That loss rate will only continue as the climate heats up.

So is Greenland lost? Evidently, it is.

The drama here is that one characteristic of tipping points is that once you press the on button you cannot stop it. It takes over. It’s too late. It’s not like you could say, ‘Oops now I realise I didn’t want to melt the Greenland ice sheet. Let’s back off.’ Then it’s too late. The important point to make here is that everything in the Earth system is connected. When one part of the climate system crosses its tipping point, then that might make it more likely for other parts of the system to also cross their critical thresholds. So you can think of this in terms of dominoes. If you tip one of them over, then this might lead to cascading effect. – Prof. Jason Box in Breaking Boundaries: The Science of our Planet.

Fig. 3: Russian Arctic heat map shows air temperatures up to 45°C in some places 19 June 2020. The heat has been linked to thawing permafrost, melting methane clathrates, widespread wildfires, and swarms of tree-eating moths in the region. (Image: European Union, Copernicus Sentinel-3)
Fig. 3: Russian Arctic heat map shows air temperatures up to 45°C in some places 19 June 2020. The heat has been linked to thawing permafrost, melting methane clathrates, widespread wildfires, and swarms of tree-eating moths in the region. (Image: European Union, Copernicus Sentinel-3)
 Video 6: At COP26, over 100 countries including Aotearoa signed a global    pledge to cut methane emissions 30% below 2020 levels by 2030 in    recognition of the serious threat we face today. “Many scientists are convinced    there is a real threat of a methane bomb or methane outbreak of very large   magnitude sufficient to perhaps cause an immediate warming of at least one   degree.”   In 2024 the National led Government revoked this pledge by refusing to bring     the agricultural sector, the largest emitter of methane, into the Emissions   Trading Scheme.

Atlantic Meridional Overturning Circulation (AMOC) Current:

The AMOC is literally a conveyor belt for exchanging heat and nutrients across four of the five world’s major oceans. The current, which moves nearly 20 million cubic metres of water per second, is driven in part by the formation of Arctic sea ice each year. When ocean water freezes, it leaves salt behind, making the surrounding water denser and heavier, so it sinks. The scale of sea ice formation was so large that until recently, the sinking salty water is one of the the world’s largest waterfalls (the largest is around Antarctica explained here). Research in 2023  indicates the AMOC will shut down this century, and the implications are global. Amongst other impacts, it would send Europe into a mini ice, cause havoc to Monsoon rains across Asia and Africa, and accelerate warming in the Southern Hemisphere including Aotearoa. On the upside, the cooling in the North Atlantic could help stabilise the Greenland ice sheet.

Video 7: Stefan Rahmstorf, Professor of Physics of the Oceans, at the Arctic Circle Assembly in Reykjavik 19 October 2024. Rahmstorf presented a letter by 44 AMOC and tipping point experts to the Icelandic climate minister Guðlaugur Þór Þórðarson: recent science suggests it has been greatly underestimated.

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