Energy Efficiency, Solar Energy and R&D in the United States' Path to Carbon Neutrality by 2050: Evidence From Rolling Window Wavelet Quantile Correlation

ABSTRACT Achieving carbon neutrality by 2050 is a central objective of United States climate policy, yet carbon emissions remain persistently high despite expanding clean‐energy and innovation initiatives. This study examines how energy efficiency, solar energy consumption, economic growth, trade openness and research and development (R&D) affect US carbon emissions over the period 1990Q1–2024Q4. To capture nonlinear, asymmetric, and time‐varying relationships across emission regimes, the study employs the Rolling Window Wavelet Quantile Correlation (RWWQC) approach, complemented by Quantile‐on‐Quantile Regression (QQR) for robustness. The results indicate that energy efficiency and solar energy consumption significantly reduce carbon emissions, particularly in high‐emission regimes and over medium‐ to long‐run horizons, while R&D expenditure contributes to emission reductions in the long run. In contrast, economic growth and trade openness tend to increase emissions at lower and moderate quantiles, although their effects weaken at higher emission levels. Based on these findings, the study proposes targeted policy recommendations emphasising energy efficiency, renewable energy expansion, innovation‐driven decarbonisation, and environmentally aligned trade to support the US pathway toward carbon neutrality by 2050.