Experts: Which climate tipping point is the most concerning? – Carbon Brief

International Conference on Climate Tipping Points Highlights Urgent SDG Challenges

Last week, the University of Exeter hosted an international conference attended by hundreds of scientists, policymakers, and journalists to discuss critical climate “tipping points.” These tipping points represent thresholds in Earth systems that, once crossed, could lead to irreversible environmental changes. The event emphasized the importance of addressing these challenges in alignment with the United Nations Sustainable Development Goals (SDGs), particularly those related to climate action, life on land, life below water, and sustainable communities.

Key Earth System Tipping Points Discussed

Experts at the conference examined several high-risk Earth system tipping points, including:

• The dieback of the Amazon rainforest
• The melting of the Greenland ice sheet
• The potential shutdown of the Atlantic Meridional Overturning Circulation (AMOC)

These tipping points have profound implications for SDG 13 (Climate Action), SDG 15 (Life on Land), and SDG 14 (Life Below Water), as they threaten biodiversity, disrupt ecosystems, and impact global climate regulation.

Exploration of Positive Social Tipping Points

In addition to environmental risks, the conference explored “positive tipping points” — large-scale, self-propelling social changes that could significantly reduce human impact on the climate. These social transformations are critical to achieving SDG 12 (Responsible Consumption and Production) and SDG 11 (Sustainable Cities and Communities), fostering sustainable behaviors and policies worldwide.

Expert Perspectives on Concerning Climate Tipping Points

On the sidelines of the conference, Carbon Brief collected insights from leading experts regarding the tipping points they find most concerning. Their responses underscore the interconnectedness of climate risks and the SDGs.

Summary of Expert Concerns

1. Prof Gabi Hegerl: Concerned about biosphere and human-related tipping points affecting food security, livelihoods, and ecosystems, linking to SDG 2 (Zero Hunger) and SDG 3 (Good Health and Well-being).
2. Prof Carlos Nobre: Highlights the Amazon dieback’s potential to release 250 billion tonnes of CO2, threatening SDG 13 and biodiversity (SDG 15).
3. Gaia Vince: Notes that coral reef ecosystems have likely passed tipping points, impacting marine biodiversity and fisheries (SDG 14).
4. Dr Andrew Hartley: Emphasizes Amazon forest dieback’s impact on the carbon cycle and global food security (SDG 2, SDG 13).
5. Prof Tim Lenton: Warns about the catastrophic global consequences of AMOC collapse, affecting water security and agriculture (SDG 6, SDG 2).
6. Prof Peter Cox: Focuses on Amazon dieback driven by climate change and deforestation, affecting multiple SDGs including SDG 15 and SDG 13.
7. Prof Johan Rockström: Concerned about coral reef systems’ vulnerability with limited scientific uncertainty, impacting SDG 14.
8. Dr Patricia Pinho: Stresses the irreversible global effects of Amazon dieback, affecting climate regulation and biodiversity (SDG 13, SDG 15).
9. Prof Ricarda Winkelmann: Highlights risks to Greenland and West Antarctic ice sheets even at lower warming levels, with implications for SDG 13 and SDG 14.
10. Dr Nico Wunderling: Notes the combined threat of climate change and deforestation on the Amazon, lowering tipping thresholds (SDG 13, SDG 15).
11. Dr Rebecca Shaw: Points to coral reef loss affecting over one billion people’s nutrition and livelihoods (SDG 2, SDG 14).
12. Dr David Obura: Highlights ice tipping elements as triggers for cascading impacts, including on AMOC and Amazon (SDG 13, SDG 15).
13. Dr David Armstrong McKay: Warns Amazon is closer to a deforestation-induced tipping point, threatening biodiversity and agriculture (SDG 15, SDG 2).
14. Kate Raworth: Emphasizes the critical social tipping point of transforming mindsets towards a regenerative economy, underpinning all SDGs.

Detailed Expert Insights and SDG Implications

Prof Gabi Hegerl

Prof Hegerl expressed particular concern about tipping points involving the biosphere and human systems, such as heat and drought thresholds that impact food availability, livelihoods, and ecosystems. These issues directly relate to SDG 2 (Zero Hunger), SDG 3 (Good Health and Well-being), and SDG 15 (Life on Land).

Prof Carlos Nobre

Prof Nobre highlighted the Amazon rainforest as a critical tipping point due to its potential to release approximately 250 billion tonnes of CO2 by 2100, jeopardizing efforts to limit global warming to 1.5°C (SDG 13). The Amazon also supports unparalleled biodiversity (SDG 15) and regulates regional and global climate systems.

Gaia Vince

Vince noted that coral reefs have likely already passed tipping points, which threatens marine biodiversity and fisheries that support over one billion people’s nutrition and livelihoods, aligning with SDG 14 (Life Below Water) and SDG 2 (Zero Hunger).

Dr Andrew Hartley

Dr Hartley emphasized the Amazon’s role in the carbon cycle and its influence on global food security, particularly through commodity markets such as soybean and maize, linking to SDG 2 and SDG 13.

Prof Tim Lenton

Prof Lenton warned that a collapse of the AMOC would cause widespread water crises, reduce viable agricultural land, and disrupt monsoon systems, potentially displacing hundreds of millions of people, impacting SDG 6 (Clean Water and Sanitation), SDG 2, and SDG 11 (Sustainable Cities and Communities).

Prof Peter Cox

Prof Cox focused on the dual stressors of climate change and deforestation accelerating Amazon dieback, which threatens multiple SDGs including SDG 13 and SDG 15.

Prof Johan Rockström

Prof Rockström identified coral reefs as a highly vulnerable tipping element with limited scientific uncertainty, threatening ocean food webs and the livelihoods of 400 million people (SDG 14).

Dr Patricia Pinho

Dr Pinho stressed the Amazon’s global climate regulation services and the irreversible nature of dieback, highlighting the need to protect Indigenous peoples and ecosystems, supporting SDG 13, SDG 15, and SDG 10 (Reduced Inequalities).

Prof Ricarda Winkelmann

Prof Winkelmann expressed concern about the Greenland and West Antarctic ice sheets, which are at risk even at lower warming levels, with implications for sea level rise and SDG 13.

Dr Nico Wunderling

Dr Wunderling highlighted the combined threat of climate change and deforestation on the Amazon, which lowers the threshold for tipping points, emphasizing the urgency for integrated climate and land-use policies (SDG 13, SDG 15).

Dr Rebecca Shaw

Dr Shaw emphasized the coral reef tipping point as a signal of ecosystem collapse that affects over one billion people’s nutrition and livelihoods, underscoring the importance of SDG 2 and SDG 14.

Dr David Obura

Dr Obura highlighted ice tipping elements as the first to be lost, triggering cascading impacts on other systems such as the AMOC and Amazon rainforest, affecting SDG 13 and SDG 15.

Dr David Armstrong McKay

Dr McKay pointed out that the Amazon is closer to a deforestation-induced tipping point than a climate change-induced one, with significant consequences for biodiversity and agriculture (SDG 15, SDG 2).

Kate Raworth

Kate Raworth emphasized the critical need for a social tipping point involving a transformation of mindsets towards a regenerative economy, which underpins the achievement of all SDGs by addressing the root causes of environmental degradation.

Conclusion: Integrating Climate Tipping Points with Sustainable Development Goals

The conference underscored that addressing climate tipping points is essential for achieving the Sustainable Development Goals. The interconnected nature of environmental, social, and economic systems means that tipping points in Earth systems directly threaten SDGs related to climate action, biodiversity, food security, water availability, and sustainable communities.

Experts called for urgent, integrated action to:

• Mitigate greenhouse gas emissions to limit global warming (SDG 13)
• Protect and restore critical ecosystems such as the Amazon rainforest and coral reefs (SDG 14, SDG 15)
• Promote sustainable land use and reduce deforestation (SDG 15)
• Support vulnerable populations, including Indigenous communities (SDG 10)
• Foster social transformations towards regenerative economies and sustainable consumption (SDG 12)

These efforts are vital to prevent irreversible climate impacts and to secure a sustainable future aligned with the 2030 Agenda for Sustainable Development.

1. Sustainable Development Goals (SDGs) Addressed or Connected

1. SDG 13: Climate Action
   • The article focuses extensively on climate tipping points such as Amazon dieback, ice sheet melting, and ocean circulation collapse, all central to climate action.
2. SDG 15: Life on Land
   • Concerns about deforestation, biodiversity loss, and ecosystem degradation, particularly in the Amazon rainforest, relate to this goal.
3. SDG 14: Life Below Water
   • Coral reef ecosystem collapse and ocean acidification are key issues discussed, linking to marine biodiversity protection.
4. SDG 2: Zero Hunger
   • Food security impacts due to climate tipping points affecting agriculture and fisheries are highlighted.
5. SDG 6: Clean Water and Sanitation
   • Water crises and monsoon collapses linked to AMOC disruption affect water availability and quality.
6. SDG 3: Good Health and Well-being
   • Risks of epidemics and pandemics due to biodiversity loss and ecosystem collapse are mentioned.
7. SDG 12: Responsible Consumption and Production
   • Deforestation and land-use change are linked to unsustainable practices.
8. SDG 11: Sustainable Cities and Communities
   • Displacement of populations due to climate impacts such as droughts and monsoon failures is discussed.

2. Specific Targets Under Those SDGs Identified

1. SDG 13: Climate Action
   • Target 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters.
   • Target 13.2: Integrate climate change measures into national policies, strategies, and planning.
   • Target 13.3: Improve education, awareness-raising and human and institutional capacity on climate change mitigation, adaptation, impact reduction.
2. SDG 15: Life on Land
   • Target 15.1: Ensure the conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services.
   • Target 15.2: Promote the implementation of sustainable management of all types of forests, halt deforestation, restore degraded forests.
   • Target 15.5: Take urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity.
3. SDG 14: Life Below Water
   • Target 14.2: Sustainably manage and protect marine and coastal ecosystems to avoid significant adverse impacts.
   • Target 14.3: Minimize and address the impacts of ocean acidification.
4. SDG 2: Zero Hunger
   • Target 2.4: Ensure sustainable food production systems and implement resilient agricultural practices.
5. SDG 6: Clean Water and Sanitation
   • Target 6.4: Increase water-use efficiency and ensure sustainable withdrawals to address water scarcity.
6. SDG 3: Good Health and Well-being
   • Target 3.3: End epidemics of communicable diseases and reduce the impact of emerging diseases.
7. SDG 12: Responsible Consumption and Production
   • Target 12.2: Achieve sustainable management and efficient use of natural resources.
8. SDG 11: Sustainable Cities and Communities
   • Target 11.5: Reduce the number of deaths and people affected by disasters, including water-related disasters.

3. Indicators Mentioned or Implied to Measure Progress

1. Carbon Emissions and Greenhouse Gas Concentrations
   • Quantities of CO2 released from Amazon dieback and permafrost melting (e.g., 250bn tonnes CO2 by 2100) serve as indicators of climate impact.
2. Temperature Thresholds
   • Global warming levels (e.g., 1.5°C, 2°C, 3-4°C) are used to assess risk of tipping points.
3. Forest Cover and Deforestation Rates
   • Deforestation levels in the Amazon and land-use change rates indicate ecosystem health and tipping risk.
4. Biodiversity and Species Extinction Rates
   • Loss of biodiversity in coral reefs and Amazon rainforest as a measure of ecosystem degradation.
5. Ice Sheet Mass and Sea Level Rise
   • Melting rates of Greenland and Antarctic ice sheets and consequent sea level rise (e.g., 3 meters in 200 years) are indicators.
6. Ocean Circulation Strength (AMOC)
   • Measurements of Atlantic Meridional Overturning Circulation strength and stability as indicators of ocean system health.
7. Food Security Metrics
   • Availability and production levels of staple crops like wheat, maize, soybean affected by climate impacts.
8. Water Availability and Crisis Indicators
   • Incidence of water scarcity and monsoon collapse events.
9. Social Indicators
   • Population displacement and migration due to climate-related disasters and tipping points.
   • Changes in societal mindsets and adoption of regenerative economic models (implied social tipping points).

4. Table: SDGs, Targets and Indicators

SDGs	Targets	Indicators
SDG 13: Climate Action	13.1: Strengthen resilience and adaptive capacity to climate hazards 13.2: Integrate climate change measures into policies 13.3: Improve education and capacity on climate change	CO2 emissions from Amazon dieback (~250bn tonnes by 2100) Global temperature thresholds (1.5°C, 2°C, 3-4°C) AMOC strength and stability measurements
SDG 15: Life on Land	15.1: Conservation and restoration of terrestrial ecosystems 15.2: Halt deforestation and promote sustainable forest management 15.5: Reduce biodiversity loss	Deforestation rates in Amazon rainforest Biodiversity loss and species extinction rates Forest cover change
SDG 14: Life Below Water	14.2: Protect marine and coastal ecosystems 14.3: Address ocean acidification	Coral reef ecosystem health and bleaching events Ocean acidification levels
SDG 2: Zero Hunger	2.4: Sustainable food production and resilient agriculture	Production levels of staple crops (wheat, maize, soybean) Food security indicators
SDG 6: Clean Water and Sanitation	6.4: Increase water-use efficiency and sustainable withdrawals	Water scarcity incidence Monsoon collapse events
SDG 3: Good Health and Well-being	3.3: End epidemics and reduce emerging diseases	Incidence of epidemics and pandemics linked to biodiversity loss
SDG 12: Responsible Consumption and Production	12.2: Sustainable management and efficient use of natural resources	Deforestation and land-use change rates
SDG 11: Sustainable Cities and Communities	11.5: Reduce deaths and affected people from disasters	Population displacement and migration due to climate disasters

Source: carbonbrief.org