As goverments argue, and petro-states and fossil fuel companies derail negotations at COP28, prominent climate scientist Professor Bill McGuire from University College in London is sounding an alarm on climate tipping points. Professor McGuire has pointed out a stark reality. The world is hurtling towards irreversible climate tipping points, rendering the goal of a safe planet unattainable. The Net Zero by 2050 benchmark for climate action will almost certainly be way too little and way too late. It's time for faster and deeper action now.
Climate tipping points are moments when slow, reversible change becomes irreversible, often with dramatic consequences. Once crossed, they trigger self-perpetuating switches in the system, defying attempts at reversal within human lifespans and confounding even the most sophisticated models. Previously perceived as threats only if global temperatures rose above 4°C, science now shows that critical components of the climate system could tip with a mere 1°C increase. We've already passed that mark, temperatures are now close to permanently hitting 1.5°C, and spikes are breaching the 2°C mark. The alarm bells should be ringing louder than ever.
Tipping points reveal a daunting array of catastrophes. Cryosphere tipping points involve massive shifts in the planet's frozen water, including collapses of the Greenland and West Antarctic ice sheets, spelling rises of over 10 metres in global sea levels. Similarly, abrupt thawing of Nothern Hemisphere permafrost would release vast quantities of methane which is around 30 times more powerful than CO2 as a greenhouse gas. Tipping points in the biosphere include the potential loss of the Amazon Rainforest and high-latitude boreal forests. And in ocean systems, the Gulf Stream and the Atlantic Meridional Overturning Circulation are likely to become serious tipping points for global weather patterns.
The critical question is not whether tipping points exist, but how soon we cross them. Progress in the science and continued growth in emissions increasingly indicate that they will occur sooner than assessed. Predictions indicate a permanent breach of the 1.5°C mark will occur in less than a decade. And without a change in emissions trajectories, the 2°C threshold will be surpassed well before 2050.
The tipping point for the Sub-polar Gyre, a system of rotating currents in the northernmost Atlantic, is likely to have already been surpassed. Once locked in, this will have severe consequences for North Atlantic temperatures and global weather patterns. And the Atlantic Meridional Overturning Circulation could shut down by 2050. The Greenland and West Antarctic ice sheets have estimated threshold temperatures of 1.5°C, so they may also already be on irreversible paths. A 2°C temperature rise, risks irreversible consequences like dieback of the Amazon Rainforest and unstoppable melting of the East Antarctic Ice Sheet. And regional tipping points, such as thawing of Northern Hemisphere permafrost and decay of mountain glaciers are adding to the urgency.
Compounding all of these risks is the potential for cascading tipping elements, where the knock on effects of one tipping point accelerate the timing and esclation of others, creating a domino effect with devastating consequences for the environment, society and economies.
We are already living in the reality of a new climate which is more dangerous than ever. The world is on the brink of surpassing the 1.5°C threshold, and the nonlinear relationship between global heating and tipping points triggered by this overshoot will be extremely perilous. Without stronger and more immediate action, Earth's climate system will be pushed well beyond the point of no return. The time to act is now. Australia and the world must cease with denial and delay. We must stop faffing around, urgently phase out fossil fuels and prepare for the consequences of climate collapse that is already locked in.
