Think back to September last year. What happened at the beginning of that month? What news shocked the world and reverberated for weeks, if not months?
That’s a question I’ve been asking friends and colleagues lately.
On September 8, 2022, at 6:30 p.m. in Great Britain, Buckingham Palace announced the death of Queen Elizabeth II. The news broke just 30 minutes before the press embargo lifted against a major overview of the tipping points of climate change in the journal Science.
The article in Science was truly earth-shattering, as it announced changes that could threaten the future of civil society on this planet. But it was the other news that caught the attention of the world.
So in case you missed it, I’d like to point you to this important paper by British climate researcher David Armstrong MᶜKay and colleagues.
Read more: Climate tipping points could stand in the way of unstoppable changes on the planet – how close are they?
Climate Tipping Points: The Point of No Return? A quick guide.
Struggling with tipping points
The question of when global warming could push elements of the climate system past points of no return has come into focus over the past decade. And tipping points ever thought to be far away in the distance are sharply embossed.
The research examines key features of the global climate system, such as ice sheets, glaciers, rainforests and coral reefs. It asks when the melting of the ice sheets in Greenland and West Antarctica would become irreversible and eventually contribute many meters to sea level rise. Or when thawing frozen ground in the Arctic could produce so much methane and carbon dioxide (CO₂) that it would inflate the global emissions budget.
The dieback of the Amazon rainforest is another important part of the Earth’s climate system. Global warming and regional decreases in rainfall can cause trees to die, releasing large amounts of greenhouse gases. Fewer trees ultimately means less precipitation for those that remain, creating a vicious circle.
The pivotal paper in Science reviewed more than 220 papers published since 2008 to estimate what level of global temperature rise (relative to pre-industrial levels) would cause each of the global and regional climate tipping points.
Global warming threshold estimates for climate reversal elements, ranging from the minimum in yellow where reversal is possible, to maximum in dark red where reversal is highly likely, the central dotted line is the best estimate. Compare to the Paris Agreement range of 1.5℃ to <2℃ (green horizontal bar). Future projections are shown in more detail in (B) along with estimated warming trajectories for the 21st century. In (C), the number of thresholds potentially exceeded in the coming decades (depending on the warming trajectory) is shown per decade (bars) and cumulatively (lines).
Reprinted with permission from David I. Armstrong McKay et al., Science 377:eabn7950 (2022). (https://www.science.org/doi/full/10.1126/science.abn7950)
The world has already warmed 1.1℃ (see the horizontal line “current warming” in the graph above). The lines of 1.5 ℃ and 2 ℃ represent the goals of the Paris Agreement on climate change agreed internationally in 2016.
Once started, the irreversible melting of the Greenland ice sheet would add about 5 meters to global sea level. It is alarming that the threshold for this tipping point may already have been crossed. If not, it is “very likely” to be crossed at 2℃.
Ice sheets in West Antarctica contain about another 3.5m of sea level rise, and again irreversible melting is likely to begin at about 2℃.
So that’s about 5 meters from Greenland and another 3.5 meters from West Antarctica. Add to that the thermal expansion of the warming oceans and the melting of mountain glaciers, and we are dealing with more than 10 meters of sea level rise.
While that will unfold over many centuries, it will be irreversible and inexorable. It means that children born today are likely to see sea levels rise by more than 1 meter in the early 22nd century. In the longer term, these changes will shape the planet for the next 150,000 years, until the next Ice Age.
Consider how 10 meters of sea level rise could change the map ClimateCentral.
Read more: Deluges of Antarctic meltwater are slowing the currents that cause our vital ocean to ‘topple over’ – and threaten to collapse
Many of the world’s tropical coral reefs are likely to die from 1.5℃ to 2℃ of warming. And thawing Arctic permafrost would release massive amounts of greenhouse gases, equivalent to about 10% of human emissions. That would likely raise global temperatures by another 0.5℃ to 1.0℃ (on top of 2℃).
Fortunately, aside from logging and wildfires, the Amazon rainforest looks relatively safe until about 3℃ of warming. But the combination of some of those other tipping points could get us there and set off a further cascade of tipping points.
Can we prevent a disaster?
After decades of delay, our chances of keeping global warming below 1.5℃ are pretty slim. But this research clearly shows that limiting warming to 2℃ will not keep us safe.
The focus on “net zero in 2050‘ actually did us a disservice. If we let emissions stay near current levels for much longer, by 2030 we will have used up the carbon emissions budget that would allow us to stay close to 1.5℃.
We need to act quickly and cut current emissions by at least half by 2030, on our way to net zero before 2050. This research shows that if we don’t, sea levels will rise by 10 meters or more. That will gradually displace hundreds of millions of people and many of the world’s largest cities.
The Intergovernmental Panel on Climate Change (IPCC) has started talking about the possible failure of civil society in response to increasing extreme events. We are seeing early indicators of this in Australia, with people living in tents for years after flooding has been made worse by climate change. They face decisions about whether or not to rebuild on that land.
How long will funding be available to provide disaster relief in Australia and around the world? Where will hundreds of millions of people go after extreme displacement wet bulb temperaturefailed harvests, fire, floods and sea level rise?
How did we get here?
Arriving at this point in human history feels like a huge failure. A failure of leadership, of decision-making, of information dissemination through the media, and perhaps our priorities, has put us in this most challenging position.
Many factors have conspired against us. These include fossil fuel companies funding misinformation and climate-related “greenwashing” – exaggerating or misrepresenting their climate credentials. Elected leaders are influenced by donations from the fossil fuel industry. Previous low-resolution climate models failed to capture local-scale processes and therefore underestimated the sensitivity of the climate system. Poor media communication about the urgency of the problem. And throw in some good old human “optimistic bias” for positive results.
As a climate scientist, with nearly 18 years of operations experience at the Bureau of Meteorology and more recently in my work on high-resolution climate projections to the state government, I deeply know the climate grief communicated so eloquently by climate researcher Joelle Gergis.
In response, I’ve had to use tools like meditation and mindfulness to deal with the awareness that science provides, including the likely future suffering of so many. It is a challenge to see where we are going and – with what is at stake – to see life go on as if everything is fine.
Read more: Introducing Fear and Wonder: The Conversation’s new climate podcast
A turning point
Future events will challenge us in many ways. Humanity faces a choice between retreating into fear and war, or cooperation and collaboration. Much is already happening and there is much we can do, as individuals and communities. We can restore landscapesreward sustainability, create a circular economy and electrify everything. But we must act quickly.
So, as the coronation of King Charles III plays on our TV screens and media feeds in the coming days, keep the incredibly urgent climate crisis in mind. Ask our leaders to stand up. Don’t be distracted, because future generations will judge us by the choices we make today.
Read more: ‘It’s possible. It must happen’: IPCC delivers final report on climate change, and where to now