A Guide to Climate Tipping Points

Making sense of a world on edge

Image Credit: Environmental Defense Fund

This article is part of a series:

• Introduction: What are tipping points?
• 1. The Arctic
• 2. The Antarctic
• 3. The Oceans
• 4. The Weather
• Reflection: Where to start?

The ice caps are melting. The rainforest is burning. The coral reef is dying. These days, we hear these messages so frequently that it is hard to know where to direct our attention. How do these issues affect you? Which ones are most pressing? Are there any you haven’t heard about? How do they relate to each other and the overall health of the planet?

Drawing on the latest research and predictions, I will help you demystify these questions, focus your attention, and make sense of new reports as they continue to come in from around the world.

What Are Climate Tipping Points?

Imagine chopping a tree. Initially, your axe chisels away at the trunk with no discernible change in the tree as a whole. Eventually, a single whack causes the tree to topple over. It reaches a tipping point. Like all tipping points, it is sudden, unpredictable, and difficult (or impossible) to reverse.

In 2005, 36 leading climate scientists convened at the British Embassy in Berlin to discuss tipping points at a planetary scale. Specifically, they were looking at large-scale ecological systems which, under stress from rising global temperatures, might cross a threshold into a new state. For example, large swaths of the Amazon Rainforest changing to savanna. These systems are known as tipping elements. In 2008, they published their findings in a paper that has since been cited and elaborated on more than 3,000 times.

Why do these tipping elements matter? Some directly impact life on our planet through extreme weather, sea level rise, and mass extinctions. Others feed back into the climate cycle, further accumulating greenhouse gases and increasing global temperatures. The dieback of the Amazon Rainforest, for example, could result in multiple effects, including mass extinction, drought, and the release of additional carbon. The changes would be hard to reverse.

Tipping elements make it clear that climate change is not experienced equally around the world. We often talk in terms of average global temperature increases, but regions are heating up at different rates and are subject to disturbances at different thresholds.

What are these tipping elements? In this article, I will outline each of the elements identified by the Environmental Defense Fund in 2017. For many of them, their tipping points produce cascading effects, creating chains I call “super-elements.” Thinking about them in this way can help you understand their aggregate effects and root causes. These include:

Elements in the Arctic, driven by accelerating local temperatures as the Arctic sea ice melts:

1. Disappearance of Arctic Summer Sea Ice
2. Melting of the Greenland Ice Sheet
3. Disruption of Ocean Circulation Patterns
4. Ocean Anoxia
5. Permafrost Melting
6. Tundra Transition to Boreal Forest
7. Dieback of Boreal Forests
8. Appearance of Arctic Ozone Hole
9. Slowdown of the Jet Stream

Elements in the Antarctic, maintaining a feedback loop between ice melting and ocean activity:

1. Disintegration of the West Antarctic Ice Sheet
2. Collapse of Deep Antarctic Ocean Circulation

Elements in the oceans, driven by increased absorption of heat and CO2:

1. Weakening of the Marine Carbon Pump
2. Collapse of Coral Reefs
3. Release of Marine Methane Hydrates

Elements in the weather, accelerated by changes in air circulation and water cycles:

1. More Permanent El Niño State
2. Dieback of the Amazon Rainforest
3. Chaotic Indian Summer Monsoon
4. Melting of the Himalayan Glaciers
5. Greening of the Sahara/Sahel
6. Aridification of Southwest North America

In the posts that follow, I will elaborate on each of these tipping elements in turn, including how they are changing today, when they might reach tipping points, and what we can do about it. At the end, I reflect on where our attention is needed most.

In the course of discussion, I reference projections made by climate models, which differ in the scenarios they investigate. I try to standardize the scenarios in terms of expected global mean temperature increases (e.g. 1.5 or 2 °C) by year 2100 in comparison to pre-industrial levels. For context, current levels have already increased by 1.1 °C, and global temperature reduction lags behind greenhouse gas emissions reduction and drawdown.

This article is part of a series:

• Introduction: What are tipping points?
• 1. The Arctic
• 2. The Antarctic
• 3. The Oceans
• 4. The Weather
• Reflection: Where to start?