Lower Interest Rates Linked to Reduced Greenhouse Gas Emissions in South Africa: New Springer Study from Nelson Mandela University

Breakthrough Findings from Nelson Mandela University Researchers

A groundbreaking study published today in Springer's Discover Sustainability journal has uncovered a direct link between the South African Reserve Bank's (SARB) monetary policy and the nation's greenhouse gas (GHG) emissions. Led by economists Aphelelamantande Mangaliso and Andrew Phiri from the Department of Economics at Nelson Mandela University (NMU) in Port Elizabeth, the research demonstrates that lower interest rates—particularly the SARB's repo rate—correlate positively with reduced GHG emissions. This finding challenges conventional views by showing how expansionary monetary policy can inadvertently support environmental goals in a developing economy like South Africa.

The study, spanning data from 1991 to 2023, employs advanced econometric techniques including the Nonlinear Autoregressive Distributed Lag (NARDL) model, Quantile Autoregressive Distributed Lag (QARDL) model, and wavelet coherence analysis. These methods reveal asymmetric effects: while lower interest rates lower the cost of capital, encouraging investments in renewable energy and energy-efficient technologies, higher rates stifle such green projects, leading to elevated emissions.

Nelson Mandela University, a key player in South African higher education, continues to produce impactful research that bridges economics and sustainability. Aspiring researchers and academics can explore opportunities in such interdisciplinary fields through platforms like higher-ed jobs in South Africa.

South Africa's Monetary Policy Landscape and Environmental Challenges

South Africa's economy has long grappled with high GHG emissions, primarily from coal-dependent energy production, contributing around 1% of global totals yet facing peak emissions of over 500 million tonnes of CO2 equivalent (MtCO2e) in recent years. Emissions have shown a slight decline post-2020, aligning with the Just Energy Transition Partnership (JETP) and carbon tax implementations, but challenges persist amid economic pressures.

The SARB, mandated with inflation targeting, has maintained a relatively low-interest-rate environment. The repo rate stood at 6.75% as of January 2026, following cuts from higher levels during the post-COVID recovery. This policy stance, while aimed at growth and price stability, now reveals unintended environmental benefits as per the NMU study.

Unpacking the Study's Methodology and Data Insights

Mangaliso and Phiri analyzed annual data on GHG emissions and key monetary variables, including the SARB repo rate as a proxy for monetary policy stance. The NARDL model captures short- and long-run asymmetries, showing that positive interest rate shocks (tightening) increase emissions, while negative shocks (easing) decrease them. The QARDL extends this to quantiles, indicating stronger effects during high-emission periods, and wavelet analysis confirms long-term co-movements strengthening post-2010.

• NARDL Key Insight: Expansionary policy supports green investments by reducing borrowing costs.
• QARDL Finding: Relationship intensifies at higher emission quantiles.
• Wavelet Coherence: Post-2010 dominance of long-term positive interest-emissions nexus.

This rigorous approach addresses limitations in prior linear panel studies, providing SA-specific evidence.

How Lower Interest Rates Drive Emission Reductions

Lower repo rates make capital cheaper for firms investing in solar farms, wind energy, or efficient manufacturing—key to SA's renewable push. For instance, since 2020, private renewable investments surged amid low rates, contributing to a 9.7% emissions drop from 2019 peaks. The study quotes: "expansionary monetary policy reduces the cost of capital for renewable and cleaner investment projects, thereby supporting emissions mitigation."

In contrast, rate hikes during inflationary periods (e.g., 2022-2023) delayed green projects, exacerbating emissions. This mechanism is vital for SA, where energy accounts for 80% of GHGs.

SARB's Evolving Stance on Climate and Monetary Policy

The SARB has increasingly integrated climate risks, publishing working papers like "Climate change shocks and monetary policy in South Africa" (2025), urging flexible frameworks. Deputy Governor Fundi Tshazibana noted green dual rates as "non-starters," favoring complementary tools like carbon taxes.

Recent papers affirm green monetary policy complements fiscal measures, aligning with the NMU findings.SARB Working Paper on Climate and Price Stability

Real-World Examples: Green Investments Thriving Under Low Rates

SA's renewable sector boomed post-2020 rate cuts: over 6GW of new solar/wind capacity added by 2025, financed via green bonds yielding lower amid cheap capital. Eskom's transition and private IPPs exemplify how low rates spurred R200bn+ investments, curbing coal emissions.

• ReNamaka Solar Plant: Financed at low rates, offsets 240,000 tonnes CO2/year.
• Wind farms in Northern Cape: Low-cost debt accelerated deployment.

Economists at universities like Stellenbosch and Wits echo this, researching fiscal-monetary synergies for net-zero by 2050.

Stakeholder Perspectives and Expert Opinions

SARB Governor Lesetja Kganyago has emphasized climate in MPC decisions. Experts like Prof. Andrew Phiri highlight: "The SARB’s low-interest-rate environment can naturally complement fiscal and energy policies." Environmental groups praise the linkage, urging sustained easing.

Government's carbon tax (R159/tCO2e in 2026) pairs well, but inflation risks loom.Explore South Africa academic opportunities

Challenges: Balancing Inflation Control and Green Goals

While low rates aid emissions, they risk fueling inflation (currently ~4-5%), testing SARB's mandate. Prolonged tightening could derail JETP, per NMU analysis. Solutions include targeted green lending facilities, as piloted by SARB.

Implications for South Africa's Climate Commitments

SA's NDC targets 350-420 MtCO2e by 2030; low rates could accelerate via 20% offset allowances in carbon tax Phase 2. Universities like NMU drive evidence-based policy.

The Role of Higher Education in Green Economic Research

SA universities are pivotal: NMU's Economics Department leads, alongside UCT's climate finance hub and Wits' sustainability centers. PhD programs in green economics prepare experts. Check higher-ed career advice for paths in this field.

Future Outlook and Actionable Policy Recommendations

Prospects: Integrate emissions into SARB models, green QE pilots. For academics, collaborate on DSGE simulations. Policymakers: Sustain low rates judiciously.

In summary, this NMU study illuminates monetary policy's environmental leverage. Explore rate my professor, higher-ed jobs, university jobs, or higher-ed career advice to join SA's green research vanguard. Share insights in comments below.

Photo by Sasun Bughdaryan on Unsplash