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 agree 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.
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.
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 8)
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.
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
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 5).
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 the 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
The melting cryosphere:
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. A tipping point is the point beyond which a change becomes irreversible. So 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. When we cross tipping points, we unleash irreversible changes that would mean that the planet who go from are best friend, where it dampens and reduces the stress, sucking out carbon dioxide and taking up heat-absorbing impacts, and tipping over to a point where it could self-reinforce warming. – Prof. Jason Box in Breaking Boundaries: The Science of our Planet (Video 1).
