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Evidence & Impacts: dangerous tipping points

Evidence: dangerous tipping points

Greenland 2019 – image: Steffen M. Olsen, Danish Meteorological Institute

Dangerous tipping points

Summary

 
  • Tipping points are the proverbial ‘last straw that breaks the camel’s back’. 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 (Video 4) that can’t be undone even when the conditions that caused them to tip are reversed (see stratocumulus clouds for example).
  • These ‘tipping points’ (Fig. 1) are often non-linear. That is:

(1) they generally happen abruptly rather than gradually, and with little to no warning

(2) they may be irreversible in human time-frames

(3) there is no way to control them

(4) some will trigger massive carbon emissions from what once were natural carbon sinks (such as the Amazon rainforest and permafrost)

(5) they threaten the natural world and us (Video 1).

Greenland 2019 – image: Steffen M. Olsen, Danish Meteorological Institute

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 (Video 4) that can’t be undone even when the conditions that caused them to tip are reversed (see stratocumulus clouds for example).
  • These ‘tipping points’ (Fig. 1) are often non-linear, i.e. they:

(1) generally happen abruptly rather than gradually, and with little to no warning

(2) may be irreversible in human time-frames

(3) there is no way to control them

(4) some will trigger massive carbon emissions from what once were natural carbon sinks (such as the Amazon rainforest and permafrost)

(5) they threaten the natural world and us (Video 1).

Video 1: in ‘Breaking Boundaries: The Science of Our Planet’, Sir David Attenborough succinctly explains tipping points. This is a short version of the full documentary of the same name, available on Netflix. Video 3 below is a more in-depth presentation of Earth’s operating manual and the research behind the findings.

Global tipping points

Tipping points shown in Fig. 1 have global physical, economic, and social impacts outside the scope of this website. For further information see Carbon Brief’s website (Fig. 1), Video 4 below, and this this free to access paper in the journal Nature.

One of the characteristics of tipping points is that once a system has been tipped into a new state, it can’t be returned to its original state simply by undoing the even that tipped it into a new state. For example, if all (not just carbon dioxide) greenhouse gases in the atmosphere reach 1200ppm, stratocumulus clouds that block 30-60% of the warming from the sun, disappear. But fo them to start reforming again, , greenhouse gas concentrations would need to drop below 300ppm.

Another example of this process is the south-east Amazonian rainforest, which now appears to have reached a point at which plants return more CO2 into the atmosphere than they absorb. Similarly, the June 2021 heatwave in the Pacific Northwest coast that killed an estimated 1 billion marine animals and over 500 people, generated a massive increase in wildfires. Losing biodiversity coupled with an average of just one degree of warming globally, has ‘tipped’ heavily forested regions from being carbon sinks to carbon sources. If similar temperatures occur over the next few years, it may not be possible for forests to recover; they will have tipped into a new state, one that does not support their future existence.

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 as well as a livable climate.

Fig. 1 (Image: Rosamund Pearce/Tom Prater for Carbon Brief)

Tipping points covered in more depth on this website: 

Biodiversity loss:

Threats are from introduced pest plants and animals that thrive in a changing climate, ongoing agricultural expansion, pollutants entering waterways, demands for reliable water for irrigation, bulldozing marine ecosystems through bottom trawling, and an Emissions Trading Scheme that financially incentivises monoculture radiata pine plantations over the protection and restoration of biodiverse native ecosystems. Once tipping points for some native ecosystems and species are reached, the ecosystem services they provided (including flood mitigation, coastal defenses against rising sea levels, and long term carbon sequestration), are, along with some critically endangered species, gone forever.

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:

The latest research (Dec. 2021) indicates that the Arctic is melting 4x faster (not 2x as often cited by journalists) than the rest of the planet. Irreversible melting of glaciers, Arctic sea ice, Greenland, and Antarctica already is underway. This is leading to accelerated rising sea levels, changes in ocean currents, more extreme weather events, loss of critical ecosystem services (biodiversity), social and economic impacts. Moreover, millennia-old carbon storage systems once regarded as stablepermafrost and clathratesare now disgorging vast quantities of greenhouse gases  (Video 3), which means our carbon budget is already over-drawn. In Antarctica, the Thwaites Glacier is also close collapsing:

If current rates of surface lowering persist, the entire Thwaites Eastern Ice Shelf will unpin from the seafloor in less than a decade, despite our finding from airborne radar data that the seafloor underneath the pinning point is about 200 m shallower than previously reported. – Wild et al, 2021.

Having two caps of a permanent ice in the Arctic and Antarctica is the very precondition for the planet to stay in a state that has enabled us to develop civilizations as we know it. Whether it’s a small glacier or whether we’re talking about Greenland, they all add together to this fantastic capacity of cooling the planet.

Icecaps and glaciers are reflecting back 90 to 95% of incoming heat from the sun. 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 their system. A tipping point is the point beyond which a change becomes irreversible. So in the current climate, Greenland is already beyond its threshold where it’s now losing 10,000 cubic metres of ice per second. That loss rate will only continue as the climate heats up.

So is Greenland lost? Evidently, it is.

The drama here is that one characteristic of tipping points is that once you press the on button you cannot stop it. It takes over. It’s too late. It’s not like you could say, ‘Oops now I realise I didn’t want to melt the Greenland ice sheet. Let’s back off.’ Then it’s too late.

The important point to make here is that everything in the Earth system is connected. When one part of the climate system crosses its tipping point, then that might make it more likely for other parts of the system to also cross their critical thresholds. So you can think of this in terms of dominoes. If you tip one of them over, then this might lead to cascading effect. When we cross tipping points, we unleash irreversible changes that would mean that the planet who go from are best friend, where it dampens and reduces the stress, sucking out carbon dioxide and taking up heat-absorbing impacts, and tipping over to a point where it could self-reinforce warming. – Breaking Boundaries: The Science of our Planet (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

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.

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 and methane clathrates ,widespread wildfires, and swarms of tree-eating moths in the region. (Image: European Union, Copernicus Sentinel-3)

Video 3: At COP26, over 100 countries including New Zealand signed a global pledge to cut methane emissions 30% below 2020 levels by 2030 in recognition of the serious threat we face today. “Many scientists are convinced there is a real threat of a methane bomb or methane outbreak of very large magnitude sufficient to perhaps cause an immediate warming of at least one degree.”

Video 4: This video starts 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 Earth has operated over the past 4.6 billion years, and the impacts of climate change.

More information