Building “Net-Zero-Aligned” Portfolios

An increasing number of investors support a transition to a net-zero economy. But the global economy is not decarbonizing fast enough to meet critical climate targets, such as the goal to limit global warming to 1.5°C, as outlined in the Paris Agreement. Investment portfolios play a vital role in supporting this transition by aligning with net-zero goals. But achieving alignment remains challenging due to varying definitions of net zero, sectoral and regional differences, and the complexities of constructing realistic decarbonization pathways.

“Building ‘Net-Zero-Aligned’ Portfolios” offers a robust framework for aligning investment portfolios with net-zero goals, addressing challenges, and seizing opportunities in the transition to a decarbonized future. The research team from Bloomberg that authored the paper posits that through continuous adaptation and collaboration, portfolio managers can drive meaningful progress toward global climate objectives.

This paper provides a comprehensive framework for constructing net-zero-aligned portfolios, emphasizing the need for clear assumptions, adaptability, and continuous management. By integrating insights into carbon budgets, transition pathways, and sectoral and regional dynamics, the paper aims to equip investors with tools to align their strategies with net-zero objectives while addressing real-world challenges.

The paper discusses some of these challenges and proposes a methodology that allows for the construction of portfolios or indexes that are consistent with net-zero goals. In particular, the authors recommend the use of granular regional and sector-specific emission pathways to allow investors to make effective use of their risk budget.

The 1.5°C Threshold

Limiting global warming to 1.5°C is critical to reducing severe climate risks. Each fraction of warming increases the frequency of extreme weather events, biodiversity loss, and the likelihood of irreversible tipping points, such as ice sheet collapse or disrupted ocean currents. Beyond 2.0°C, the Earth’s systems risk destabilization due to feedback mechanisms, such as reduced sea ice reflectivity and methane release from permafrost. Given the uncertainty in the models used to link emissions to temperature rise and several assumptions made during the portfolio construction exercise, it makes sense to target a lower temperature rise goal—hence the 1.5°C threshold used in the paper.

Indeed, the carbon budget—the maximum amount of carbon dioxide (CO_²) that can be emitted into the atmosphere while still limiting global warming to a specific temperature threshold—is an estimate, not a fixed value, due to uncertainties in climate models and Earth System dynamics. Different models, such as Earth System simulations and integrated assessment models, produce varying estimates based on such factors as feedback loops and natural variability. The paper explains that emitting an additional 500 gigatons of CO^₂ gives a 50% chance of exceeding 1.5°C, demonstrating the probabilistic nature of carbon budget calculations.

These complexities highlight the need for urgent action and clear strategies to manage emissions. Aligning investments with net-zero goals requires understanding these uncertainties while committing to reducing emissions to avoid overshooting this critical threshold.

Aligning Portfolios with Net Zero

Aligning investment portfolios with net zero presents several challenges, beginning with the lack of a universally agreed-on definition of net zero, which leads to inconsistencies in implementation. Sectors and regions have vastly different emission profiles and decarbonization trajectories, complicating the creation of realistic, cross-sectoral strategies. Adhering to a carbon budget requires constant monitoring and periodic rebalancing of portfolio weights, which can be resource intensive and technically complex. In addition, the analytical challenges of constructing decarbonization pathways that reflect both global and local realities demand sophisticated data modeling and scenario analysis. Finally, organizational resistance, outdated infrastructure, and regulatory uncertainties create further barriers to achieving and maintaining alignment with net-zero goals. These challenges underscore the need for clear frameworks, collaborative efforts, and innovative tools to overcome obstacles and drive meaningful progress.

Key Takeaways

• Cumulative emissions are critical. Net zero depends on limiting total emissions over time, not just annual reductions.
• Carbon budgets guide decisions. Investors should use carbon budgets to cap emissions and align portfolios with temperature targets.
• Sector and regional differences matter. Emission profiles and decarbonization pathways vary, requiring tailored strategies.
• Rebalancing is important. Ongoing adjustments ensure portfolios stay aligned with evolving carbon budget constraints.
• Scenario selection drives outcomes. Choosing appropriate pathways is crucial to reflect feasible and realistic decarbonization goals.
• Engagement and collaboration are key. Stakeholders, including issuers and regulators, must work together to overcome alignment challenges.

This paper proposes a methodology that uses modeled transition pathways to allocate carbon budgets across portfolios while considering regional and sectoral specifics. By incorporating projected emissions and historical trends, the approach dynamically evaluates current and future alignment with net-zero targets. A “net-zero-alignment score” simplifies these assessments, enabling optimized portfolio construction with such tools as the Bloomberg Optimizer to maximize environmental impact within tracking error constraints.

The methodology supports further research, including simulations with diverse transition pathways, refining peer group definitions, and integrating proxies for company transition credibility. Despite existing data limitations, the approach offers a platform to improve net-zero portfolio construction, aiming for robust alignment strategies that evolve with data and insights. Continued innovation and refinement are necessary to address climate-aligned investing challenges effectively.

The Paper’s Authors

Antonios Lazanas, Global Head of Portfolio, Index, and Sustainability Quant Research, Bloomberg, New York City

Zarvan Khambatta, CFA, Global Head of Sustainability Quant Research, Bloomberg, New York City

Yingjin Gan, Global Head of Index Research, Bloomberg, New York City

Lingjuan Ma, Senior Researcher, Index Research Team, Bloomberg, London

Niall Smith, Senior Researcher, Sustainability Quant Research Team, Bloomberg, London