Climate Tipping Points

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Evidence suggests that several elements of the climate system could be tipped into a different state by global warming, causing irreversible economic damages (1).

With scientists warning that the window to prevent the Earth’s climate hitting irreversible tipping points is fast closing, an increasingly strident activism movement says a strong signal from the summit is the only acceptable outcome.

Reuters December 13, 2019

What are Climate Tipping Points?

The phrase “tipping point” passed its own tipping point and caught fire after author Malcolm Gladwell’s so-named 2000 book. It’s now frequently used in discussions about climate change, but what are “climate tipping points”? (2).

The literature on the costs of climate change often links climatic “tipping points” and large economic shocks that are often called “catastrophes”. The phrase “tipping points” in this context can be misleading because the subsequent changes can be either abrupt or slow. If the lag between crossing a critical threshold and an impact is too long, we may not notice until it’s too late to do anything about it. If we notice that we’ve done something wrong, it may be possible to intervene and limit the damage (2).

From “Critical Phenomena” to “Tipping Points”

Until about the year 2004, climate scientists used the phrase ‘critical phenomena’ to describe dynamics associated with threshold effects which would lead to qualitative changes in the system state such as deglaciation. This concept of a critical phenomenon is reasonably well defined in physics, where it has a meaning distinct from its usage in social sciences. In physics, a system becomes ‘critical’ if it is on the cusp of transforming into a new condition. ‘Critical thresholds’ identify system states or forcing levels which are about to trigger a critical phenomenon. Since 2005, however, prominent climate scientists have used ‘tipping point’ to evoke the prospect of accelerated, or irreversible, global warming. The phrase, mainly used first in the mass media, has since permeated the mainstream academic literature, the language of politicians and funding agencies. (3)

Should we Use the Terminology of Tipping Points?

The concept and terminology of tipping points have been widely used to invoke the danger of passing thresholds of irreversible and/or abrupt change in the near-immediate future. But how helpful is this metaphor for climate science and for climate change communication? There are different views on how helpful is this metaphor is. One view argues that the tipping point concept may have some limitations as a description of the mathematical behaviour of Earth system models trying to simulate the world’s climate. But its use can alert decision-makers to the possibility of some rapid and/or serious changes in the climate system which need attention as part of responsible and accountable policymaking. In contrast, others argue that the concept risks exaggerating the immediacy and severity of climate change and offers a false prospectus of there being a ‘cliff-edge’ within the climate system. Climate change is primarily a problem of incremental cumulative harm and the concept of tipping point offers a false emphasis on abruptness and harms the public understanding of climate science. (3)

Some are pointing out that if the system has already moved past a tipping point, a full recovery can occur. There may be a recovery point in the aftermath of a tipping point that can be predicted (4).

The concept of a tipping point is nevertheless helpful for describing and communicating possible climate futures. It bridges knowledge established with climate models with the concerns of climate governance and accountable risk management.

Nine Active Tipping Points

Nine crucial tipping points in Earth’s climate are now “active” and in danger of being crossed thanks to warming global temperatures caused by human activity.

The nine active tipping points are (5):

1. Arctic sea ice
2. Greenland ice sheet
3. Boreal forests
4. Permafrost
5. Atlantic Meridional Overturning Circulation
6. Amazon rainforest
7. Warm-water corals
8. West Antarctic Ice Sheet
9. Parts of East Antarctica

The collapse of major ice sheets on Greenland, West Antarctica and part of East Antarctica would commit the world to around 10 meters of irreversible sea-level rise.

Reducing emissions could slow this process, allowing more time for low-lying populations to move.

The rainforests, permafrost, and boreal forests are examples of biosphere tipping points that if crossed result in the release of additional greenhouse gases amplifying warming.

These climate thresholds, such as the decline of ice sheets and loss of biodiverse habitats, could cumulatively trigger a global tipping point that would be “an existential threat to civilization”.

Climate science is clear: the world faces a massive ecological and humanitarian crisis. The climate emergency is the defining and most urgent issue of our time, and it cannot be avoided without a global shift away from fossil-fuel dependency.

The UN Climate Change Conference – COP 25 – Madrid, Spain, December 2019

References: 

1. Yongyang Cai, Timothy M. Lenton and Thomas S. Lontzek, Risk of multiple interacting tipping points should encourage rapid CO2 emission reduction, Nature March 2016
2. Rutgers University. “Climate tipping points: What do they mean for society?.” ScienceDaily. ScienceDaily, 11 July 2016. <www.sciencedaily.com/releases/2016/07/160711122607.htm>.
3. Hulme, Mike (ed.) Contemporary Climate Change Debates: A Student Primer, Routledge 2020 (Pages displayed by permission of Routledge)
4. Junjie Jiang, Alan Hastings and Ying-Cheng Lai, Harnessing tipping points in complex ecological networks, Royal Society September 2019
5. Nine climate tipping points now ‘active,’ warn scientists, University of Exeter, Science Daily.  November 2019

Lucubrate Magazine December 2019

The picture on the top of the article by anastasianess (Adobe Stock)

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