Population changes and sustainability of energy drive cooling demand related risks in urbanized India

Abstract

Global warming poses a challenge to India’s energy policy as rising temperatures coincide with population growth and lifestyle changes to substantial increase cooling energy requirements. The concept of cooling degree-days (CDD) is often used to assess probable changes in cooling demands but, to date, no study has considered CDD changes within a risk framework to consider exposure and underlying vulnerabilities of a population. Here, we quantify the trends in observed CDD data across administrative divisions of India for 1951–2019. Using temperature data from five climate models under three representative concentration pathways (RCPs), we then estimate the relative changes in average annual CDD across India under 1.5 °C, 2 °C and 3 °C levels of global warming. We further quantify the risk associated with increased cooling requirements for most urbanized regions of India using CDD as hazard, population as exposure, and two alternative vulnerability metrics that account for economic conditions (per capita Gross Domestic Product, GDP) and energy source (proportion of renewable energy to total energy). For 62% of administrative units, the Pettitt’s test identified a statistically significant change point in annual CDD values, with 1993 as the median year of change. Climate model projections suggest a likely increase of 5–14%, 13–80% and 22–160% in average annual CDD values for a majority (>90%) of administrative units under the 1.5 °C, 2 °C and 3 °C levels of global warming, respectively. The risk assessment showed that population exposure was the primary factor governing risk scores when per capita GDP was used as a proxy for vulnerability. Risk scores differed substantially when the vulnerability index was based on contribution of non-renewables to electricity requirements. Our analysis emphasizes that prevailing socio-economic conditions and energy policies are likely to play a strong role in mitigating climate change impacts related to cooling energy requirements in urbanized Indian regions.