In 2021, with just over 1°C of global warming, tipping points were a significant probability. As the planet warms towards 2°C and beyond, there is higher probability that tipping points will be triggered.
While it is accepted by scientists that global warming naturally occurs in the ice age cycle, carbon pollution is heating the planet to dangerous levels. Warming oceans are losing their effectiveness as CO2 sinks; human activities are accelerating warming at an unprecedented rate. Many of the gravest threats to humanity are drawing closer.
The Global Tipping Points Report, which was launched at COP28 on 6th December, assesses the risks and opportunities of both negative and positive tipping points in the Earth system and society. It finds five important natural thresholds are already at risk of being crossed, and three more may be reached in the 2030s if the world heats more than 1.5°C above pre-industrial temperatures. Once triggered, these planetary shifts will be unstoppable and cause sweeping damage to people and nature, irreversible on human time scales.
Tipping points at risk include the collapse of big ice sheets in Greenland and the West Antarctic, the widespread thawing of permafrost, the death of coral reefs in warm waters, and the collapse of the oceanic current in the North Atlantic. All currently show evidence of loss of resilience consistent with moving towards tipping points. Early Warming Systems (EWS) can provide an indication of a tipping point approaching, and should be taken as a chance to prevent it from happening.
Unlike changes to the climate, such as hotter heatwaves and heavier rainfall, these systems do not slowly shift in line with greenhouse gas emissions but can instead flip from one state to an entirely different one. When a climatic system tips – sometimes with a sudden shock – it may permanently alter the way the planet works.
- The Arctic has warmed nearly four times faster than the rest of the globe since 1979.
- Self-reinforcing feedbacks, like melting ice caps, push the Earth System toward a planetary threshold that, if crossed, could prevent stabilisation of the climate.
- It may also lead to cascading events in which tipping points interact, leading to more profound changes to the entire system.
- Changes of this magnitude threaten worldwide societal collapse or even eventual human extinction.
Recent research has confirmed that tipping points and cascades are already occurring, not at 1.5°C or 2°C of warming, but right now:
- Denman Glacier, in East Antarctic, was identified as susceptible to collapse of its ice shelf and inundation of the glacier itself.
- Scientists announced the Thwaites Glacier ice shelf in West Antarctica was fracturing and likely to result in a speeding up of the glacier’s flow and ice discharge.
- In November 2022, the State of the Cryosphere report concluded more than four meters of additional sea level rise was locked in.
- A few months later, scientists reported that Greenland Ice Sheet glaciers are melting 100 times faster than previously calculated.
- By 2022, 20% of the Amazon rainforest had been ‘transformed’ (deforested) with another 6% ‘highly degraded’. At higher temperatures, the amount of carbon dioxide absorbed by plants (photosynthesis) will decline sharply, whilst carbon dioxide released by plants (respiration) will continue to rise.
- Human fossil fuel emissions are still rising and will not likely plateau until the end of this decade.
- Permafrost carbon emissions and their feedback loops are not accounted for in most Earth system models or Integrated Assessment Models.
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Pauline Meechan, Sherwood Forest Friends of the Earth