emissions compatible with climate boundaries – Nature

Report on Climate Boundaries and Sustainable Development Goals (SDGs)

Introduction: Aligning Climate Action with Planetary Sustainability

This report details a modelling framework designed to analyze climate boundaries, which are defined as the planetary limits within which humanity can sustainably operate and prosper. The analysis focuses on pathways for anthropogenic CO₂ emissions, carbon dioxide removal (CDR), and solar radiation management (SRM) that are compatible with these boundaries. This research is fundamentally aligned with the United Nations Sustainable Development Goals (SDGs), particularly SDG 13 (Climate Action), by providing a quantitative basis for developing sustainable future strategies.

Key Climate Boundaries and Relevant SDGs

The framework assesses four critical climate system boundaries, each directly linked to specific SDGs, highlighting the interconnected nature of global sustainability challenges.

• Global Warming: Limiting global temperature rise is the central objective of SDG 13 (Climate Action). The model evaluates pathways to remain within the 2°C warming boundary.
• Ocean Acidification: This directly threatens marine ecosystems and the livelihoods that depend on them, making it a core concern for SDG 14 (Life Below Water).
• Sea-Level Rise: Rising sea levels pose a direct threat to coastal populations and infrastructure, impacting progress towards SDG 11 (Sustainable Cities and Communities) and SDG 1 (No Poverty).
• Arctic Sea-Ice Melt: The loss of Arctic sea ice is a critical indicator of climate change that affects global weather patterns and biodiversity, with implications for SDG 13 and SDG 15 (Life on Land).

Analysis of Mitigation Pathways and Safety Levels

The study introduces the concept of “safety levels,” representing the probability of staying within one or more climate boundaries. This probabilistic approach helps quantify the risks associated with different mitigation strategies, providing crucial information for policymakers aiming to achieve the SDGs. The analysis of mitigation options such as CDR and SRM also relates to SDG 9 (Industry, Innovation, and Infrastructure), which promotes sustainable technological development.

1. Single-Boundary Scenario (SDG 13 Focus): In a scenario where CO₂ emissions peak in 2030, net-zero is achieved by 2050, and CDR capacity reaches 10 PgC yr⁻¹, the safety level for remaining within the 2°C global warming boundary is 80%. This finding directly informs the targets of SDG 13.
2. Holistic-Boundary Scenario (Integrated SDGs): When all four boundaries (global warming, ocean acidification, sea-level rise, and Arctic sea-ice melt) are considered concurrently, the safety level for the same emissions pathway drops dramatically to 35%.

Implications for Achieving the Sustainable Development Goals

The results underscore the critical need for a holistic approach to climate policy that integrates multiple sustainability objectives. The significant reduction in the safety level from 80% to 35% demonstrates that a narrow focus on global warming alone is insufficient and risks transgressing other critical boundaries, thereby jeopardizing the achievement of interconnected goals like SDG 14 (Life Below Water) and SDG 11 (Sustainable Cities and Communities).

The key trade-offs identified between mitigation options necessitate a comprehensive assessment to develop strategies that are not only effective for climate mitigation but are sustainable across the full spectrum of the SDGs. This reinforces the principle of SDG 17 (Partnerships for the Goals), suggesting that integrated, multi-disciplinary collaboration is essential for navigating the complexities of the Earth system and ensuring a sustainable future for all.

Analysis of Sustainable Development Goals (SDGs) in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

The article’s focus on climate change and its environmental impacts directly connects to several Sustainable Development Goals. The primary SDGs addressed are:

• SDG 13: Climate Action: This is the most central SDG to the article. The entire abstract is dedicated to analyzing pathways to mitigate climate change by staying within “climate boundaries,” specifically addressing global warming caused by anthropogenic CO₂ emissions.
• SDG 14: Life Below Water: The article explicitly identifies “ocean acidification” as one of the four key boundaries being modeled. Ocean acidification is a direct consequence of increased atmospheric CO₂ and poses a significant threat to marine ecosystems, which is a core concern of SDG 14.
• SDG 15: Life on Land: The mention of “Arctic sea-ice melt” as a critical climate boundary connects the article to SDG 15. The loss of Arctic sea ice leads to the degradation of a unique natural habitat, impacting biodiversity and terrestrial ecosystems that depend on it.
• SDG 9: Industry, Innovation, and Infrastructure: The article discusses advanced technological mitigation options such as “carbon dioxide removal” and “solar radiation management.” The development and deployment of these technologies are directly related to fostering innovation for sustainable development.
• SDG 11: Sustainable Cities and Communities: The analysis of “sea-level rise” as a planetary boundary is highly relevant to SDG 11. Rising sea levels pose a direct threat to the resilience and safety of coastal cities and human settlements.

2. What specific targets under those SDGs can be identified based on the article’s content?

Based on the issues discussed, the following specific SDG targets can be identified:

1. Under SDG 13 (Climate Action):
   • Target 13.2: Integrate climate change measures into national policies, strategies and planning. The article’s analysis of pathways where “CO₂ emissions peak in 2030″ and “net-zero CO₂ is reached in 2050″ directly supports the strategic planning required by this target.
2. Under SDG 14 (Life Below Water):
   • Target 14.3: Minimize and address the impacts of ocean acidification, including through enhanced scientific cooperation at all levels. The article contributes to this target by introducing a “modelling framework to analyse… ocean acidification” and assessing emission pathways to stay within this boundary.
3. Under SDG 15 (Life on Land):
   • Target 15.5: Take urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity and, by 2020, protect and prevent the extinction of threatened species. The focus on preventing “Arctic sea-ice melt” directly relates to protecting a critical natural habitat from degradation due to climate change.
4. Under SDG 11 (Sustainable Cities and Communities):
   • Target 11.b: By 2020, substantially increase the number of cities and human settlements adopting and implementing integrated policies and plans towards inclusion, resource efficiency, mitigation and adaptation to climate change, disaster risk reduction. The article’s modeling of “sea-level rise” provides critical data for developing adaptation and mitigation plans to protect vulnerable coastal communities.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

Yes, the article mentions or implies several specific, quantifiable indicators that can be used to measure progress:

• Global Temperature Increase: The article explicitly uses the “global warming boundary of 2 °C” as a key metric. This serves as a direct indicator for measuring progress on climate mitigation efforts under SDG 13.
• CO₂ Emission Levels: The article discusses “anthropogenic CO₂ emissions” and specific milestones like peaking emissions by 2030 and achieving “net-zero CO₂” by 2050. These are critical indicators for tracking emission reduction progress.
• Carbon Dioxide Removal (CDR) Capacity: A specific capacity of “10 PgC yr⁻¹” for carbon dioxide removal is mentioned. This provides a measurable indicator of the technological capacity required for climate mitigation, relevant to SDG 9 and SDG 13.
• Ocean Acidification Levels: While a specific pH value is not given, “ocean acidification” is treated as a measurable boundary within the model, implying that changes in ocean chemistry are a key indicator for SDG 14.
• Sea-Level Rise: “Sea-level rise” is identified as another measurable boundary. The rate and total amount of sea-level rise are direct indicators of climate change impacts, relevant to SDG 11 and SDG 13.
• Arctic Sea-Ice Extent: “Arctic sea-ice melt” is the fourth boundary analyzed. The extent and volume of Arctic sea ice are crucial indicators for the health of polar ecosystems (SDG 15) and the global climate system (SDG 13).

4. Summary Table of SDGs, Targets, and Indicators

Source: nature.com