Path to net zero is critical to climate outcome.

Area of Science:

• Climate Science
• Environmental Policy
• Greenhouse Gas Mitigation

Background:

• Net zero greenhouse gas targets are central to climate action strategies globally.
• Current climate pledges often prioritize the net zero year, overlooking the critical role of emissions pathways.
• The distinction between long-lived (carbon dioxide) and short-lived (methane) greenhouse gases necessitates nuanced mitigation approaches.

Purpose of the Study:

• To analyze the impact of different greenhouse gas emissions pathways on global warming outcomes.
• To evaluate the effectiveness of various mitigation strategies in meeting long-term climate goals.
• To provide recommendations for enhancing climate action targets beyond simple net zero year commitments.

Main Methods:

• Modeling of climate outcomes based on distinct pathways for carbon dioxide and methane emissions.
• Comparison of warming differences in midcentury and end-of-century under various net zero scenarios.
• Assessment of the sufficiency of single-basket versus two-basket approaches for interim climate targets.

Main Results:

• Different emissions pathways can result in significant warming differences (up to 0.4°C by midcentury), even with identical net zero years.
• Potential for exceeding the 2°C warming limit exists depending on the emissions pathway, despite achieving net zero by 2050.
• A 0.2°C warming difference persists by the end of the century between analyzed pathways.

Conclusions:

• Simultaneous early action on both carbon dioxide and methane emissions yields the most favorable climate outcomes across all time scales.
• Supplementing net zero targets with interim milestones for both gases is recommended for effective climate mitigation.
• A single-basket approach for climate targets may delay crucial methane mitigation efforts.