Cooling access and energy requirements for adaptation to heat stress in megacities

Abstract

As urban areas are increasingly exposed to high temperatures, lack of access to residential thermal comfort is a challenge with dramatic consequences for human health and well-being. Air-conditioning (AC) can provide relief against heat stress, but a massive AC uptake could entail stark energy demand growth and mitigation challenges. Slums pose additional risks due to poor building quality, failing to provide adequate shelter from severe climatic conditions. Thus, it is unclear how many people in the Global South will still lack access to basic cooling under different future climate and socioeconomic developments. We assess the impact of different shared socioeconomic pathways (SSPs) and climate futures on the extent of population lacking access to cooling where needed—the cooling gap—and energy requirements for basic comfort for a set of 22 megacities in the Global South. We find that different SSPs greatly influence the extent of future cooling gaps, generally larger in SSP3 due low income levels, and consequent limited access to AC and durable housing. Megacities in Sub-Saharan Africa and South Asia have the largest share of population affected, ranging from 33% (SSP1) to 86% (SSP3) by mid-century. Energy requirements to provide basic cooling for all are higher in SSP1 for most megacities, driven by urbanization, and can increase by 7 to 23% moving from 2.0 to 3.0 °C temperature rise levels. Strategies combining improved building design and efficient cooling systems can improve adaptation to heat stress in cities while reducing energy and emission requirements to reach climate and sustainability goals.

Sectoral investments to achieve water, energy and land Sustainable Development Goals and enhance climate resilience

“…Integrated assessment models (IAMs) have also expanded and developed their representation of the energy supply and demand sectors, water infrastructure and land and agriculture systems to study long-term development scenarios (Khan et al, 2017;Kulkarni et al, 2022;Mastrucci et al, 2021;McCollum et al, 2018;Parkinson et al, 2019;Soergel et al, 2021;van Soest et al, 2019;. At the same time, climate change already shows its effects on the abovementioned sectors in terms of mean temperature and water availability affecting crop yields, which have direct impacts on energy supply potential and demand, water and food provision and needs (Awais et al, 2024;Denissen et al, 2022;Gernaat et al, 2021;Immerzeel et al, 2010;Jägermeyr et al, 2021;Lutz et al, 2016;Mastrucci et al, 2022;van Vliet et al, 2016). There are clear linkages between climate impacts and global or intra-national inequalities and development, with the most vulnerable and poor countries being most likely exposed to extreme change and having at the same time the lowest capacity to adapt (Andrijevic et al, 2023;Byers et al, 2018).…”

Inequalities in global residential cooling energy use to 2050

“…Previous studies have used different techniques, including empirical regression models 5,[13][14][15][16] and bottom-up engineering approaches 17,18 , to analyse the decision of purchasing and utilising air conditioning in different contexts and at different scales. For instance, at the cities level 19,20 , country level [21][22][23] , multi-country level 5,14,24 , or globally 13,15 .…”