Evidence: dangerous tipping points
(Image: Steffen M. Olsen, Danish Meteorological Institute, Greenland 2019)
Dangerous tipping points
- Earth systems are complex, dynamic, and interdependent. While they can absorb small shocks, large changes and feedback effects can push them to critical thresholds beyond which a tiny change will ‘tip’ them into very different states like falling dominoes (Video 3).
- Tipping points (Fig. 1) are often non-linear, i.e, they often happen abruptly rather than gradually, may be irreversible in human time-frames, and trigger greenhouse gas emissions from natural sinks (e.g., melting permafrost and the Amazon rainforest turning from a carbon sink into a carbon source) over which we have no control, threatening both the natural environment and us (Video 1).
- Greenhouse gas emissions and biodiversity loss—over which we do have control—are passing critical thresholds, tipping the climate into a state that we humans have never before experienced.
- Governments agree that to ‘avoid a critical threshold above which the planet could experience irreversible catastrophic impacts‘, global temperatures must not exceed 1.5°C above pre-Industrial levels. However, calculations how to stay below 1.5°C ignore tipping points.
IPCC reports in 2019 indicated that major tipping points could be reached between 1°C – 2°C. We have passed 1.2°C and the United Nations state that key tipping points are being breached. Even if countries act on the Paris agreement to reduce emissions, we are on track to reach more than 3°C before the end of the century, and according to the World Meteorological Organisation, were may briefly hit 1.5°C before 2026. The potential domino effect of of tipping points have implications so complex and widespread only those with the most immediate impacts on New Zealand are outlined on this website:
- Biodiversity loss: threats from introduced pest plants and animals that thrive in a changing climate, ongoing agricultural expansion and pollutants, and demands for reliable water for irrigation
“Since the 2012…over a hundred thousand hectares of true land-use change [has been] going on around wetlands, scrub being cleared, and dairy land-use intensification.” – Landcare Research, 2020
“Even the most egregious offences – including a dam built on a wetland, clearance of a nationally endangered form of kānuka, and aerial poisoning of swathes of regenerating native bush – often prompted little more than a warning from authorities.” – Charlie Mitchell, Stuff, 2020
- The melting cryosphere: Arctic sea ice, Greenland, permafrost, (eg. Fig. 2), and Antarctica: leading to accelerated rising sea levels, more extreme weather events, loss of critical ecosystem services (biodiversity), social and economic impacts
- Changes in ocean currents: leading to extreme weather events, loss of critical ecosystem services (biodiversity), social and conomic impacts.
“Having two caps of a permanent ice in the Arctic and Antarctica is the very precondition for the planet to stay in the state that has enabled us to develop civilizations as we know it. When these ice sheets start melting you can come to a point where the ice sheets tip over from being self-cooling to becoming self-warming. And that is the most dramatic tipping point in the earth system.” – Johan Rockström (Video 1).
“In New Zealand, 72,000 people are currently exposed to present-day extreme coastal flooding, along with about 50,000 buildings worth $12.5 billion. The risk exposure increases markedly with sea-level rise, particularly during the first metre of rise…. There is near certainty that the sea will rise 20-30cm by 2040.” – NIWA
Other tipping points include the point at which plants return more CO2 into the atmosphere than they absorb. This now appears to be the situation with the Brazilian rainforest.
The June 2021 heatwave that killed an estimated 1 billion marine animals and over 500 people along the Pacific Northwest coast is also contributing to a massive increase in wildfires, meaning that these heavily forested regions may be turning into carbon sources rather than carbon sinks.
We may be able to reverse some tipping points if we can reverse rising temperatures by drawing down excessive carbon from the atmosphere. The fastest and most cost-effective way to achieve this is by restoring natural ecosystems, which will bring the collateral benefits of healthy ecosystem services.
Video 2: Steffen M. Olsen, Danish Meteorological Institute. The ice sheet near Qaanaaq Greenland that they would normally sled across is covered in vast meltwater lakes due to extreme surface warming (17°C) in June 2019. Meltwater eventually drains into the ocean, contributing to rising sea levels and disrupting oceanic currents.
References and further reading
- 2021: Denning; Southeast Amazonia is no longer a carbon sink, Nature 595, pp354-355
- 2021: Philip et al; Rapid attribution analysis of the extraordinary heatwave on the Pacific Coast of the US and Canada June 2021. World Weather Attribution
- McSweeny; Pacific north-west heatwave shows climate is heading into ‘uncharted territory’ Carbon Brief analysis and interviews with the above researchers.
- 2021: Duffy et al; How close are we to the temperature tipping point of the terrestrial biosphere? Science Advances: 7 | 3, eaay1052
- 2021: Ritchie et al; Overshooting tipping point thresholds in a changing climate, Nature 529 pp517–523
- 2021: IPBES-IPCC- Biodiversity and Climate Change Workshop
- 2020 Carbon Brief Explainer: Nine ‘tipping points’ that could be triggered by climate change
- 2021: IPBES-IPCC- Biodiversity and Climate Change Workshop
- 2020: Turetsky et al; Carbon release through abrupt permafrost thaw, Nature Geoscience 13, pp138–143
- 2020: Keuper et al; Carbon loss from northern circumpolar permafrost soils amplified by rhizosphere priming Nature Geoscience 13, pp560-565
- 2020: Thomas et al; Tipping elements and amplified polar warming during the Last Interglacial, Quaternary Science Reviews 233 | 106222
- 2019: Lade et al; Human impacts on planetary boundaries amplified by Earth system interactions, Nature Sustainability 3, pp119–128
- 2019 NIWA: New Zealand Fluvial and Pluvial Flood Exposure; prepared for Deep South Challenge
- 2019 NIWA: Coastal Flooding Exposure Under Future Sea-level Rise for New Zealand; prepared for Deep South Challenge
- 2019: Lenton et al; Climate tipping points — too risky to bet against, Nature article (free to access)
- 2019 IPCC: Special Report on the Ocean and Cryosphere in a Changing Climate
- 2018 IPCC: Summary for Policymakers of IPCC Special Report on Global Warming of 1.5°C approved by governments
- 2018: Carbon Brief Analysis; Why the IPCC 1.5C report expanded the carbon budget
- 2017: Jones; How the World Passed a Carbon Threshold and Why It Matters, Yale Environment 360 – Yale School of Forestry & Environmental Studies
- 2017: Huntingford et al; Implications of improved representations of plant respiration in a changing climate, Nature Communications 8/1602
- 2015: United Nations Climate Change: The Paris Agreement
- 2015 Carbon Brief interactive: The Paris Agreement
- 2010: Ditlevsen: Tipping points: Early warning and wishful thinking, Geophysical Research Letters 37 | 19
- 2009: Schneider: Science as a Contact Sport, National Geographic Books NY