25 May 2022

Venue: International Environment House II & Online | Webex

Organization: Switzerland, Geneva Environment Network

Organized with Switzerland, this briefing presented the initiative asking the IPCC to elaborate a Special Report on “Climate Tipping Points and their Implications for Habitability and Resources”.

About this Session

Over the past decades, our scientific understanding of climate change has significantly grown. The IPCC reports has played a key in synthetizing the best available science on the causes of climate change, its impacts, and possible pathways to adapt to and mitigate them. Meanwhile, scientific information on large-scale singular events, tipping points and irreversibilities remains scattered. Tipping points in the climate system refer to thresholds that can occur as a consequence of human induced climate change, and that lead to changes are abrupt, high-impact, large-scale and often irreversible.

This lack of a comprehensive assessment on the issue hinders an overview of the state of knowledge and limits decision-making in accordance with Article 2 of the UNFCCC and Art. 2.1(b) of the Paris Agreement. In particular, emerging measures and the acceleration of climate change in recent years have increased the need for a comprehensive and focused assessment of tipping points in the climate system.

To respond to this need, the government of Switzerland considers it timely and pertinent to ask the IPCC to elaborate a Special Report on “Climate Tipping Points and their Implications for Habitability and Resources”, which will be prepared in the framework of the IPCC’s 7th Assessment Cycle, scheduled to start in 2023. All three IPCC Working Groups are expected to contribute to this Special Report, making it a comprehensive assessment of the topic. The timing of the approval of the report should take place around 2026 in order to serve as the basis for the second UNFCCC Global Stocktake from 2026 to 2028, and well before the second commitment period under the Paris Agreement in 2030.

The goal of the event is to lay out as to how the crossing of tipping points in the climate systems may impact society, environment and economies alike, across the globe.

Organized with Switzerland within the framework of the Geneva Environment Network, this event presented the initiative to governments participating in the IPCC and Parties to the UNFCCC and other interested stakeholders.



Professor of Climate and Environmental Physics, Physics Institute, University of Bern & President of the Oeschger Centre for Climate Change Research

Sebastian KÖNIG

Chief Scientist, International Affairs Division, Swiss Federal Office for the Environment (FOEN) & Focal Point for the Intergovernmental Panel on Climate Change, Switzerland


Director, Department of Environment, Climate Change and Health, World Health Organization

Alexandra BILAK

Director, Internal Displacement Monitoring Centre

Sabine PABST

Sabine PABST

Environmental and Climate Destruction & Asia Coordinator, FIAN International Secretariat


Head, United Nations Environment Programme's Finance Initiative


Director, Science and Innovation Department & Chief Scientist, World Meteorological Organization


Manager at United Nations Climate Secretariat (UNFCCC) | Moderator


Coming soon

Welcome and Opening

Sebastian KÖNIG | Chief Scientist in the International Affairs Division, Swiss Federal Office for the Environment, IPCC Focal Point for Switzerland

418.9 ppm. That is the level of CO2 today. That number is already at levels last seen around four million years ago, in the Pliocene epoch, when temperatures were up to 3°C higher than  than today.  

7 Meters. That’s the equivalent of global sea level rise that the Greenland Ice Sheet holds. We now measure that Greenland is losing ice at fastest rate in 350 years.

In my own research 10 years ago, we wanted to understand how sensitive large systems like the Greenland Ice Sheet are and what the future may hold. Back then, the Greenland Ice Sheet was almost lost entirely. Once the ice is lost, it requires levels of CO2 half of the current levels and orbital configurations favorable for ice to grow, which could take multiple thousands of years.  

Politicians, economists and even some natural scientists have tended to assume that tipping points2 in the Earth system — such as the loss of Greenland Ice sheet or the Amazon rainforest — are of low probability and little understood. Yet evidence is mounting that these events could be more likely than was thought. By crossing a tipping point, the Earth is entering a new stage of a climate regime, which is irreversible, at least for a very long time.  

The Intergovernmental Panel on Climate Change (IPCC) introduced the idea of tipping points two decades ago. At that time, these ‘large-scale discontinuities’ in the climate system were considered likely only if global warming exceeded 5 °C above pre-industrial levels. However, new information suggests that tipping points could be exceeded even between 1 and 2 °C of warming. 

Representatives attending this meeting are now wondering why they should be concerned about the fate of the Greenland Ice Sheet. The answer is twofold.  

  1. First, the climate-biosphere system is interconnected: Crossing a particular tipping point will lead to feedbacks, cascading effects and to changes elsewhere on the globe, taking us to a different climate regime. Prof. Stocker will be diving into the details on that. 
  2. Second, it will have significant social and economic consequences. On these consequences, we will hear more from our distinguished panel: on how societies and economies will be and are already impacted. 

Given the high interconnected nature of the tipping points and given the far reaching consequences for mankind, we need a comprehensive understanding of the tipping points and their implications. It is hence, highly policy relevant information. 

The IPCC is the right authority and delivers the quality for such a report. Therefore, Switzerland sees it as pertinent to call for a Special Report by the IPCC in the new cycle that will start by 2023. We ask governments and other stakeholders to sign up to and join our proposal. A first step would be to have COP27 to mandate the IPCC to undertake such an assessment.   

Climate Tipping Points and their Irreversibility | Presentation of the Proposal for IPCC Special Report

Thomas STOCKER | Professor of Climate and Environmental Physics, Physics Institute, University of Bern & President of the Oeschger Centre for Climate Change Research

The IPCC has laid a great foundation to look into climate tipping points in more detail. Temperatures in the last 2000 years have increased to a level that is unprecedented in that time, where the rate of change is also unprecedented.

  • It’s useful to look back 60 million years that has been done now by IPCC in the Working Group I contribution: we find carbon dioxide concentrations as estimated 60 million years ago to 1 million years ago and the global surface temperature changed during that time.
  • There is a very tight correlation between the major greenhouse gas, carbon dioxide, and the global mean temperature as greenhouse gases and their variations modify the earth’s energy balance.
  • We have also become even more precise about these two parameters in the climate system over the last 800,000 years. If you put that together with the projections first historical development over the last hundred and 150 years and then the projections that were presented in the Fifth Assessment report.
  • The context of the changes that lie ahead of us in only the next 200-250 years, with respect to the last 60 million years. The world has the potential to be rather different from now, as seen in the evolution of the temperature on a map from the last 60 million years to today.

Emission scenarios at 2100 and 2300 timescales.

  • With regards to emission scenarios, at the time horizon of 2100 for the mitigation scenario, we’re looking at the world in which people are able in most regions to adapt to the impacts of climate change. In a world, however, where high emission scenario (SSP-8.5) would be realized, this is no longer guaranteed and many areas on this planet will go beyond the limit of habitability. This is a real danger that needs to be assessed in a more profound way.

Tipping points have happened in the past. During the last ice age, we had about 26 events where scientists believed that tipping was the element that triggered these abrupt temperature changes, as seen in the Greenland ice cores and the consequent changes around the globe, registered in the red curve as temperature variations that are correlated with the abrupt changes in Antarctica. [See graph here.] Tipping points are not a figment of a mathematical model but in fact our planet has dynamics that are seen in both global scale and regional scale tipping points.

Science has progressed in the last 20 years to identify step by step possible non-linear processes in the climate system: the interaction between the atmosphere, the ocean and the land surface, including vegetation. We have identified a number of tipping elements, some are already present in the literature as robust knowledge, others are more speculative, but that is the state of the science at the moment.

Examples of tipping points. Here are a few examples of tipping points mentioned during the presentation. Click on the image to see more details.

See presentation made during the event

Panel Discussion | Tipping Points Consequences for Society, Environment and Economies

  • Health Impacts, including vector-borne diseases and epidemics | Maria NEIRA, Director, Department of Public Health and Environment at the WHO
  • Climate change related displacements | Alexandra BILAK, Director, Internal Displacement Monitoring Centre
  • Agricultural shifts and farmland abandonment, stress on food and jobs | Sabine BAPST, Environmental and Climate Destruction & Asia Coordinator, FIAN International Secretariat
  • Financial impacts, including insurance premiums above affordability threshold | Eric USHER, Head, United Nations Environment Programme’s Finance Initiative
  • WMO’s view on the timely proposal | Jürg LUTERBACHER, Director, Science and Innovation Department & Chief Scientist, WMO

Open Discussion

Concluding Remarks


In addition to the live WebEx and social media transmissions, the video of the event is available on this webpage.





The photo for this event “Sea of Frozen Methane in Siberia” is taken by Felton Davis from Flickr (21-08-07).