by David Spratt
There can be no excuse for not knowing that 1.5°C of warming would create a disastrous outcome, but few have chosen to say so. Indeed, up to the 2025 COP in Belém, the large Australian advocacy and umbrella organizations were actively advocating for 1.5°C, for example that “the 1.5°C threshold represents an ethical and moral boundary”.
What is the morality in saying 1.5°C is an appropriate threshold when the World Health Organization concludes that more than 200,000 lives have been lost to the "silent killer" of extreme heat in Europe since 2022?
Right now, there is very strong evidence for the coming collapse of the Atlantic Meridional Overturning Circulation (AMOC), which transports tropical ocean heat to the north-east of North America and western Europe. AMOC is slowing down and now rapidly approaching a tipping point for its collapse over a hundred years. This would be a going-out-of-business scenario for north-west European agriculture, monsoons that typically deliver rain to West Africa and South Asia would become unreliable, and huge swaths of Europe and Russia would be devastated by drought. As much as half of the world’s viable area for growing corn and wheat could dry out.
And evidence has been accumulating over the last decade that tipping points have been passed for several large Earth systems. These include Arctic sea ice, the Greenland Ice Sheet, the Amundsen Sea glaciers in West Antarctica, the eastern Amazonian rainforest, and the world’s coral systems. The Earth climate system is undergoing abrupt change.
System-level change is happening faster than forecast only two decades ago, and changes are cascading. “If damaging tipping cascades can occur and a global tipping point cannot be ruled out, then this is an existential threat to civilization,” leading scientists warned in 2017.
A 2025 assessment of non-linear change in climate systems — the North Atlantic subpolar gyre, Tibetan Plateau, land permafrost, Amazon rainforest, Antarctic sea ice, monsoon systems, Arctic summer sea ice, Arctic winter sea ice, and Barents sea ice — found abrupt shifts in all of these across multiple models, except for monsoons. At global warming of 1.5°C, six out of 10 studied climate subsystems already showed large-scale abrupt shifts across multiple models.
Setting goals
There are too few words and too little focus from climate advocates, from governments and from policy-makers on these issues. Is 1.5°C a desirable end-goal, or a political trade-off? What are their goals and what are they aiming to protect? For more than a decade advocates talked a lot about 1.5°C, but now they seem to be dropping the topic from their agendas. So what’s the new goal? Two degrees?
For a quarter of a century, policymakers have speculated about the maximum climate damage that civilisation and the Earth system can tolerate and adapt to. How close to the edge of the climate cliff can we stand, without falling to our death?
Clearly, the goal pursued in mainstream climate advocacy is not the provision of “maximum protection” to the most climate vulnerable, or “concern to protect the welfare of all people, all species, and all generations”, but rather some poorly-informed notion of maximum acceptable damage.
To protect small-island states, the Great Barrier Reef, Antarctica, the Amazon — indeed to provide protection for the many places and people we care about — requires returning to a climate similar to the relatively stable Holocene conditions of the last 9000 years and fixed human settlement, during which time CO2 levels did not exceed 280 ppm CO2. it also requires preventing a cascade of tipping points in the meanwhile.
If this were the goal, activists and policymakers would be advocating a “three levers” approach to reversing global warming: a strategy to rapidly “reduce, remove and repair”. That means reducing emissions to zero at emergency speed; removing carbon by drawdown to return atmospheric conditions to the Holocene zone; and the urgent research on active cooling to identify safe interventions that protect and repair vital systems and, in the shorter term, aim to prevent warming reaching a level that triggers a cascade of calamitous tipping points that are irreversible on human timescales.
Note: This is an extract from Searching for climate action’s missing goal, available at:
https://safeclimate.org.au/paper/searching-for-climate-actions-missing-goal
