Regional Analysis

Compendium Volume: Climate-Resilient Investment in Sub-Saharan Africa

Authors' Summary: This Compendium Volume presents a series of guidance notes and more detailed complementary technical notes that offer practical insights in support of enhancing the climate resilience of infrastructure investment projects in Sub-Saharan Africa. This first introductory chapter starts with an overview of the investment conditions and climatic context in the region, followed by a description of the scope of this Compendium Volume and individual notes, target audiences, and a roadmap for users of the contents covered in this Volume.

The Changing Nature of Human-Forced Hydroclimatic Risks across Africa

Abstract: We present results from large ensembles of projected 21st century changes in seasonal precipitation and near-surface air temperature over Africa and selected sub-continental regions. These ensembles are a result of combining Monte Carlo projections from a human-Earth system model of intermediate complexity with pattern-scaled responses from climate models of the Coupled Model Intercomparison Project Phase 6. These future ensemble scenarios consider a range of global actions to abate emissions through the 21st century. We evaluate distributions of surface-air temperature and precipitation change. In all regions, we find that without any emissions or climate targets in place, there is a greater than 50% likelihood that mid-century temperatures will increase threefold over the current climate’s two-standard deviation range of variability. However, scenarios that consider more aggressive climate targets all but eliminate the risk of these salient temperature increases. A preponderance of risk toward decreased precipitation exists for much of the southern Africa region considered, and this is also compounded by enhanced warming (relative to the global trajectory). Over eastern and western Africa, the preponderance of risk in increased precipitation change is seen. Strong climate targets abate evolving regional hydroclimatic risks. Under a target to limit global climate warming to 1.5˚C by 2100, the risk of precipitation changes within Africa toward the end of this century (2065-2074) is commensurate to the risk during the 2030s without any global climate target. Thus, these regional hydroclimate risks over much Africa could be delayed by 30 years, and in doing so, provide invaluable lead-time for national efforts to prepare, fortify, and/or adapt.

Air Quality Related Equity Implications of U.S. Decarbonization Policy

Abstract: Climate policies that target greenhouse gas emissions can improve air quality by reducing co-emitted air pollutant emissions. However, the extent to which climate policy could contribute to the targets of reducing existing pollution disparities across different populations remains largely unknown. We quantify potential air pollution exposure reductions under U.S. federal carbon policy, considering implications of resulting health benefits for exposure disparities across U.S. racial/ethnic groups.

We focus on policy cases that achieve reductions of 40-60% in 2030 economy-wide carbon dioxide (CO2) emissions, when compared with 2005 emissions. The 50% CO2 reduction policy case reduces average fine particulate matter (PM2.5) exposure across racial/ethnic groups, with greatest benefit for non-Hispanic Black (-0.44 μg/m3) and white populations (-0.37 μg/m3). The average exposure disparity for racial/ethnic minorities rises from 12.4% to 13.1%. Applying an optimization approach to multiple emissions reduction scenarios, we find that no alternate combination of reductions from different CO2 sources would substantially mitigate exposure disparities.

Results suggest that CO2-based strategies for this range of reductions are insufficient for fully mitigating PM2.5 exposure disparities between white and ethnic/racial minority populations; addressing disparities may require larger-scale structural changes.

Quantifying the recreation use value of New England natural lands

Abstract: It is well recognized that natural land is of great importance, and measures of the value of natural lands are required when making data-driven policy decisions between land development and land preservation. One of the most important values of natural land areas is the recreational services provided. In this study, we apply the travel cost method to estimate the recreation use value provided by the natural land in New England. Specifically, this study calculates the total consumer surplus for hunting, fishing, and wildlife-watching in the New England region. We also investigate whether and how people from households of different race and surroundings have different recreational habits. Using data from the National Survey of Fishing, Hunting, & Wildlife-Associated Recreation, we found that New England natural lands provide a remarkable amount of recreation use value—$88 billion per year to U.S. citizens who partake in wildlife-related activities, accordingly to the travel cost method. Our estimates can serve as input for economic projection and policy analysis models and allow more equitable and appropriate data-driven policy decisions.

Emissions and energy impacts of the Inflation Reduction Act

Abstract: If goals set under the Paris Agreement are met, the world may hold warming well below 2°C; however, parties are not on track to deliver these commitments, increasing focus on policy implementation to close the gap between ambition and action. Recently, the US government passed its most prominent piece of climate legislation to date—the Inflation Reduction Act of 2022 (IRA)—designed to invest in a wide range of programs that, among other provisions, incentivize clean energy and carbon management, encourage electrification and efficiency measures, reduce methane emissions, promote domestic supply chains, and address environmental justice concerns. IRA’s scope and complexity make modeling important to understand impacts on emissions and energy systems. We leverage results from nine independent, state-of-the-art models to examine potential implications of key IRA provisions, showing economy-wide emissions reductions between 43 and 48% below 2005 levels by 2035.

This multimodel analysis provides a range of decision-relevant information. For example, international policy-makers and negotiators need to track progress toward Paris Agreement pledges, and assessing IRA’s impacts is important to monitor US efforts and to provide a template for measuring the performance of other sectors and jurisdictions. Federal and state policy-makers can use this IRA analysis to compare updated baselines with policy targets—for emissions, electric vehicle deployment, and others—to understand the magnitude of additional policies and private-sector actions needed to narrow implementation gaps. Electric companies need to know how long IRA incentives will be available, because these subsidies can continue until electricity emissions are below 25% of their 2022 levels, which requires national models to evaluate. Industry- and technology-specific deployment can support investors, technology developers, researchers, and companies to quantify market opportunities.

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