Earth’s climate is nearing
irreversible tipping points

Leading climate change researchers explain the implications of their research

By Irwin Rapoport

October 26, 2022

Climate change affects every form of life on Earth and its impacts, be they visible or hidden at the moment and waiting to burst upon the scene, are a definite reality. It is literally a choice of all hands to the pump to deal with the situation effectively to mitigate the damage that we have already caused and continue to create daily, or putting our heads in the sand and ignoring the grave problems, letting them unfold while we continue to pursue an unsustainable lifestyle, which is the case in the developed world, and the impacts of which affect people in developing nations.

Dr. David Armstrong McKay – Image: courtesy of the Stockholm Resilience Centre

The choice is ours and by ours, I mean humanity as a whole. For many years we have been warned by a number of researchers and scientists studying climate-related issues, weather, pollution, ecosystems, biodiversity, agriculture, and a host of other fields. Global warming and the ongoing destruction of the planet-wide ecosystem that sustains all life on Earth leaves no one unscathed. We have been warned countless times and thus far, the reaction is very much a case of one step forward and three steps backwards.

On the September 12, 2022, BBC Newsday program, Dr. David Armstrong McKay, a climate and biosphere scientist working with the Earth Commission and a GSI Visiting Fellow at the University of Exeter, was interviewed on the five tipping points regarding climate that are occurring and their long-term impacts. The Guardian also published an article on the tipping points report that is extremely informative and quotes several researchers.

Dr. David B. Bahr, with the Institute for Arctic and Alpine Research, University of Colorado in Boulder, was interviewed on NPR’s Here and Now program in August regarding a study on the melting of Greenland’s ice sheets and how it cannot be stopped. A study published on August 29, 2022, in Nature, Climate Change: Greenland ice sheet climate disequilibrium and committed sea-level rise, brought together researchers from several countries in terms of universities and research institutes. A Google search focuses on the situation of the Thwaites Glacier in Antarctica, which is in the process of melting and breaking up.

The situation we are facing is deadly serious, and many species of plants and animals have gone extinct due to global warming, pollution, and rapacious resource extraction. The witches’ brew we have devised is quite insidious.

Dr. Tim Lenton – Image: courtesy of the University of Exeter

Dr. David Armstrong McKay of the University of Exeter, a lead author of the tipping points study, who said “It’s really worrying. There are grounds for grief, but there are also still grounds for hope”, and Dr. Tim Lenton, also at the University of Exeter, a co-author of the analysis who said “Since I first assessed tipping points in 2008, the list has grown and our assessment of the risk they pose has increased dramatically”, graciously replied to questions sent to them by Westmount Magazine.

WM: What are the five tipping points, what impacts will each have individually, to what extent have these processes started and when will they peak? When combined, what are the impacts, and can they be reversed or are we dealing with a completely new global situation?

McKay and Lenton: In our assessment, we find that five climate tipping points may already be possible at current levels of global warming: the Greenland and West Antarctic ice sheet collapse, low-latitude coral reef die-off, widespread abrupt permafrost thaw, and the collapse of ocean convection in the Labrador-Irminger Seas.

Greenland and West Antarctica hold over 10 metres of sea level equivalent and so, the collapse of ice sheets would massively reshape global coastlines and displace many current cities and agriculture, albeit over hundreds to thousands of years. Coral reef ecosystem collapse would happen faster (around a decade) and would be an ecological tragedy, as well as impacting the hundreds of millions of people who depend on them for fisheries and coastal protection. Widespread abrupt permafrost thaw would amplify greenhouse gas emissions from permafrost thaw over the coming centuries as well as disrupt northern landscapes and infrastructure as features like thermokarst lakes and slumps form. And Labrador-Irminger Sea convection collapse would drive major North Atlantic cooling over only a decade or so, and disrupt weather patterns in Europe, North America, and West Africa.

In our analysis, these are all possible but not yet likely, and the first four listed become likely beyond 1.5C. Once triggered, most would be effectively irreversible on human timescales but limiting peak warming could help reduce the total impact (high peak warming would, for example, accelerate ice sheet collapse and eliminate coral reef refugia).

WM: How much time do we have as a global society to implement measures to avoid the impacts of the five tipping points and, based on what you are seeing, is there a will by most governments and people to act seriously to address them? Will this require drastic and immediate solutions, and could you provide some immediate actions we should take?

McKay and Lenton: Our study provides strong scientific support for the more ambitious Paris Agreement aim of limiting warming to 1.5C, and while we can’t eliminate the chance of passing tipping points at this level, it does reduce their likelihood. The IPCC has assessed that limiting warming to 1.5C would require emissions to rapidly fall by around half by the end of this decade and reach net zero by 2050, which would mean a rapid transformation of the global economy, including no further fossil fuel development (according to the International Energy Authority) and a halt to deforestation. However, current policies are putting us on a trajectory of around 2.6C by 2100, while net-zero pledges made last year at the Glasgow UN COP26 talks would lead to just under 2C if implemented, meaning we’re currently far off the sort of ambition and policies needed to get close to 1.5C.

Our study provides strong scientific support for the more ambitious Paris Agreement aim of limiting warming to 1.5C, and while we can’t eliminate the chance of passing tipping points at this level, it does reduce their likelihood.

WM: If the permafrost in the polar regions is lost, can we accurately predict the release of methane and how would you describe the impact of methane releases compared to standard carbon GHG releases?

McKay and Lenton: In our analysis, we estimate permafrost thaw/collapse as leading to around 5-10 percent amplification of global warming over centuries as a result of the ‘positive’ amplifying feedback of additional carbon dioxide and methane emissions from newly degrading organic carbon as it thaws. This is substantial feedback that makes warming harder to limit (especially to the now close Paris limits) but it’s not so big that it overtakes human-driven emissions – human emissions still dominate warming and so, cuts in human emissions can still control (in the sense that how much warming occurs is up to us rather than out of control feedbacks) how much further warming will occur.

WM: Based on the five tipping points, can we accurately predict rises in sea level, temperature increases, desertification, the health of ocean ecosystems and their biodiversity, increase in forest fires, effects on agriculture, droughts, extinction of species and loss of biodiversity, the shrinkage and loss of lakes, rivers, and wetlands, etc.?

McKay and Lenton: Providing exact estimates for tipping point impacts is tricky, but we provide estimates of global/regional warming resulting from tipping points in our study and name some broader impacts as well (e.g. 10 plus metres of sea level rise from Greenland and West Antarctic ice sheets, biodiversity loss from coral reef/Amazon dieback, etc.) Many of these are uncertain and have low confidence though but we can be sure that the impacts will be negative and should be avoided.

Sea ice reflects 50% to 70% of incoming sunlight, while the ocean, being darker, reflects only 6%. As an area of sea ice melts and exposes more ocean, more heat is absorbed by the ocean, raising temperatures that melt still more ice. This process is a positive feedback – Image: Christopher Michel, CC BY 2.0, via Wikimedia Commons

WM: When did the study start, and how much of an international effort was it?

McKay: I first started work on this in late 2019 and worked on it through the pandemic, with help from a team spread across top climate and sustainability research institutes in Sweden (where I started the work), Germany, the Netherlands, and the UK.

Lenton: I started working on this topic in the early 2000s and first identified a list of climate tipping points in 2008. I have been trying to synthesize available evidence and literature ever since. For the present study, David led the heroic work of synthesizing 220 papers published since my 2008 study.

WM: To what extent was the research based on field investigations, modelling and predictions based on ongoing impacts?

McKay and Lenton: We mostly assess existing scientific literature in this study, including studies covering modelling, palaeoclimate (i.e. records of ancient climate change), current observations, and theory from the past 15 years since the first major climate tipping points assessment in 2008. The extra novelty we add in this study are updated synthesis estimates of the thresholds, timescales, and impacts of the proposed tipping elements, as well as categorizing them based on their dynamics and judging confidence levels in all of these.

‘… while there is inevitable uncertainty around this research, self-sustaining change has been predicted and observed in many complex dynamic systems like the climate and ecosystems, and we have enough evidence from past climate change to justify taking a precautionary approach now.’

WM: From what you are seeing and hearing, what are the critics of your research saying and is much of this reaction based on political and economic ideologies? The data and conclusions put forward in the report are serious and well researched. What do you say to those people and organizations who deny the science and claim this is just another example of “doom and gloom” tactics?

McKay and Lenton: Some climate scientists are not convinced that sharp, definite thresholds exist in the climate system, and that tipping-like processes are more piecemeal across space and warming levels. We agree that it’s not a case of saying “Greenland collapse beginning or every coral reef dying off at exactly 1.5C,” which is why we present each threshold estimate as a likelihood range with tipping chances increasing with warming and categorize some tipping elements as “regional impact” (where tipping is localized to each e.g. coral reef or glacier but occurs synchronously across larger regions at some level). Further research is for sure needed here to reduce uncertainties and improve confidence on potential tipping points and work out likely dynamics in better detail – we see our study as a first attempt at such a systematic assessment that should be followed up by wider projects by the wider climate science community.

Others have less well-grounded criticism, which is clearly more politically motivated – for example, climate denialists claiming tipping points are scare stories, or at the other end, climate fatalists who think they’re all already inevitable and climate change is already out of human influence. We would counter that, while there is inevitable uncertainty around this research, self-sustaining change has been predicted and observed in many complex dynamic systems like the climate and ecosystems, and we have enough evidence from past climate change to justify taking a precautionary approach now.

Additionally, while there is evidence of positive “amplifying” feedbacks worsening climate change, our assessment indicates that the most proximal tipping points don’t substantially amplify short-term global warming, making a runaway climate change as a result of tipping points unlikely. And so climate action now is still valuable.

Starving polar bear – Many arctic animals rely on sea ice, which has been disappearing in a warming Arctic – Image: Andreas Weith, CC BY-SA 4.0, via Wikimedia Commons

WM: Deforestation in Brazil, Canada, Australia, Malaysia, Indonesia, and in other countries in Africa, South America, and Asia continues unabated, and we have countries such as Canada, the United States, and those in Africa and South America pursuing oil and gas development projects and building pipelines. Canada, for example, just approved an offshore drilling project in Newfoundland waters, and the federal government is keen to expand output via the tar sands operations along with provincial governments expanding fracking and LNG operations. Knowing the tipping points we are facing, what is your response to these actions?

McKay and Lenton: It’s clear from IPCC and IEA assessments, as well as others, that to limit warming to as close to 1.5C as possible, fossil fuel development and deforestation such as these examples would need to be halted as soon as possible, and that continuing to pursue these projects is incompatible with both the Paris Agreement and with limiting the chances of passing multiple climate tipping points. Closing the gap between the current policy trajectory (~2.6C by 2100, but 3C if we’re unlucky with feedbacks and climate sensitivity), net-zero pledges (~2C by 2100), and 1.5C would require clear commitments and concrete policies to rapidly limit further fossil fuel development and infrastructure and halt deforestation, while instead heavily investing in renewable energy, climate-resilient development, public transport-centred cities, and plant-rich food systems.

‘It’s clear from IPCC and IEA assessments, as well as others, that to limit warming to as close to 1.5C as possible, fossil fuel development and deforestation… would need to be halted as soon as possible…’

WM: What can individuals do to effectively challenge governments to change their ways, and from your perspective, are there any governments and nations that are calling for change?

McKay and Lenton: While some countries are doing better than others, no country is on track for 1.5C. Here in the UK, for example, emissions have fallen dramatically over the past decade as coal power has been phased out but the government’s independent Climate Change Committee has assessed current policies as unable to keep up this pace and the new government has recently promised to “extract every ounce of oil and gas from the North Sea,” which is clearly incompatible with a 1.5C future.

Individual lifestyle and investment change are, of course, important for people to do to help reduce emissions but it’s also critical that people also lobby their local and national governments to live up to and improve their climate promises, either directly or through social movements.

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Here are some videos from various sources that provide information on issues raised in the interview.

A PBS report on the Thwaites Glacier in Antarctica:

A PBS Newshour report featuring Dr. David Holland of New York University:

A CNN report on the loss of Greenland and other Arctic region ice shelves and glaciers:

A SKY news report on Arctic ice disappearing and the impacts that we are witnessing:

A clip from The Late Show with Stephen Colbert, featuring Samantha Power, Administrator of the United States Agency for International Development, discussing various issues, including the impacts of global warming: