In support of Zambia's Eighth National Human Development Report, UNDP and the Millennium Institute applied the Integrated Sustainable Development (iSD) model to Zambia to map the pathways through which climate change acts as a threat multiplier and to quantify its impacts on national development. Two scenarios were compared to 2050: a baseline and a Climate Resilience Scenario (CRS) based on the adaptation and mitigation interventions and costs in Zambia's 2021 NDC and the Green Growth Strategy 2024–2030, equivalent to 12% of GDP over 2024–2030 and assumed to be externally financed. The CRS raises the Human Development Index by 3% and SDG attainment by 7% by 2050, with notable gains in poverty reduction, hunger, economic growth, infrastructure, climate action and land conservation, alongside short-term trade-offs in water access, inequality and government accounts. It also lifts GDP growth, reduces unemployment and the debt-to-GDP ratio, boosts agricultural and mining output, enables surplus renewable electricity generation, and lowers greenhouse gas emissions and forest loss.