Climate Emergency Institute
Knowledge of the possibility of a global climate planetary catastrophe goes back decades. Tipping point research goes back many years​

​​The 2°C limit (1990s) ​was to minimize but not exclude the risk of runaway
However scientists have avoided the topic ​​of runaway, though close examination ​of the IPCC assessments provides evidence of the extreme risk of climate catastrophe. ​

​​Since the 2018 IPCC 1.5°C Report some top scientists have been publishing stern warnings that the world faces a global climate catastrophe, with collapse of essential global ecosystems, causing collapse of our world society and civilization.

Today's ​​Escalating international and intra-national conflict increases carbon emissions and renders any chance of an international agreement to put global emissions into decline practically 
Published 9 September 2022 by David McKay et al, Exceeding 1.5°C global warming could trigger multiple climate tipping points speaks for itself

Published ​1 August by Luke Kemp et al, Climate Endgame: Exploring catastrophic climate change scenarios- also speaks for itself too, with multiple planetary catastrophes at high and increasing risk

​Published 6 August 2018 by W ill Steffen et al, Trajectories of the Earth System in the Anthropocene, became known as the Hothouse Earth paper, for what it warned of. Multiple planetary tipping points were all projected to be triggered at 2C (see supplement), leading to a biospherecatastrophic hothouse Earth state.
​​The January 2020 most strongly worded research paper was published by an unusually large number of experts Underestimating the Challenges of Avoiding a Ghastly FutureCorey J. A. Bradshaw, Paul R. Ehrlich, Andrew Beattie, Gerardo Ceballos, Eileen Crist, Joan Diamond, Rodolfo Dirzo, Anne H. Ehrlich, John Harte, Mary Ellen Hart, Graham Pyke, Peter H. Raven, William J. Ripple, Frédérik Saltré, Christine Turnbull, Mathis Wackernagel and Daniel T. Blumstein​

​​​The paper warned and advised that this
d​​ire situation "places an extraordinary responsibility on scientists to speak out candidly and accurately when engaging with government, business, and the public. The paper through all its dire evidence is a call on scientists to be forthright on the existential to survival of civilization, the human race and most life".

The authors cover predictions of a ghastly future of mass extinction, declining health, and climate-disruption upheavals (including looming massive migrations) and resource conflicts this century. 

They urge that the gravity  of the situation requires fundamental changes to global capitalism, education, and equality, which in​clude inter alia the abolition of perpetual economic growth, properly pricing externalities, a rapid exit from fossil-fuel use, strict regulation of markets and property acquisition, reigning in corporate lobbying, and the empowerment of women. Oddly they don`t include termination of fossil fuel subsidies or explicit charging central corporate global polluters the cost of their pollution.

​​In summary the paper presents 'the state of the natural world in stark form here to help clarify the gravity of the human predicament. We also outline likely future trends in biodiversity decline (Díaz et al., 2019), climate disruption (Ripple et al., 2020), and human consumption and population growth to demonstrate the near certainty that these problems will worsen over the coming decades, with negative impacts for centuries to come. Finally, we discuss the ineffectiveness of current and planned actions that are attempting to address the ominous erosion of Earth's life-support system'. 

​​'It is therefore incumbent on experts in any discipline that deals with the future of the biosphere and human well-being to eschew reticence, avoid sugar-coating the overwhelming challenges ahead and “tell it like it is.” Anything else is misleading at best, or negligent and potentially lethal for the human enterprise at worst'.

Unmitigated (as now) catastropic climate disruption can collapse world agriculture,civilization and essential Earth systems, leading to biosphere collapse.