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Evidence: dangerous tipping points

Evidence: dangerous tipping points

(Image: Steffen M. Olsen, Danish Meteorological Institute, Greenland 2019)

Dangerous tipping points

Summary

  • 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.
Video 1: in ‘Breaking Boundaries: The Science of Our Planet’, Sir David Attenborough succinctly explains tipping points. (Video 2 is more in-depth).

Overview

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

“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

The other tipping points in Fig. 1 will also have global physical, economic, and social impacts outside the scope of this website. For further information see Carbon Brief’s website (Fig. 1) this free to access paper in Nature, and Video 3 below.

Fig. 1 (Image: Rosamund Pearce/Tom Prater for Carbon Brief)
Fig. 2: Russian Arctic heat map shows air temperatures up to 45°C in some places 19 June 2020. The heat has been linked to thawing permafrost, widespread wildfires, and swarms of tree-eating moths in the region. (Image: European Union, Copernicus Sentinel-3)

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.

The observed temperatures were so extreme that they lie far outside the range of historically observed temperatures. – Lead researchers interviewed in Carbon Brief

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

Video 3: This video begins 17 minutes into the 42-minute presentation from Earth Systems scientist Professor Will Steffen (Climate Council of Australia, Australian National University). The full video is an ideal starting point for students of all ages to understand how Earthe had operated over the past 4.6 billion years, and the impacts of climate change.