Implications of Increasing Household Air Conditioning Use Across the United States Under a Warming Climate

Soaring temperatures and increased occurrence of heatwaves have drastically increased airconditioning demand, a trend that will likely continue into the future. Yet, the impact of anthropogenic warming on household air conditioning is largely unaccounted for in the operation and planning of energy grids. Here, by leveraging the state-of-the-art in machine learning and climate model projections, we find substantial increases in future residential air conditioning demand across the U.S.-up to 8% with a range of 5%-8.5% (13% with a range of 11%-15%) after anthropogenic warming of 1.5 degrees C (2.0 degrees C) in global mean temperature. To offset this climate-induced demand, an increase in the efficiency of air conditioners by as much as 8% (+/- 4.5%) compared to current levels is needed; without this daunting technological effort, we estimate that some states will face supply inadequacies of up to 75 million "household-days" (i.e., nearly half a month per average current household) without air conditioning in a 2.0 degrees C warmer world. In the absence of effective climate mitigation and technological adaptation strategies, the U.S. will face substantial increases in air conditioning demand and, in the event of supply inadequacies, there is increased risk of leaving millions without access to space cooling during extreme temperatures. Plain Language Summary Climate change is leading to increased temperatures around the world. As temperatures rise, the demand for air conditioning increases accordingly, as people strive to keep cool. While the general pattern of projected changes is intuitive (i.e., higher temperatures lead to increased air conditioning use), the specific changes that will be experienced by households is not well understood. Here, we utilize a machine learning model to project changes to household-level air conditioning demand over the contiguous United States. Our results show significant increases to air conditioning demand in projected warming world of 1.5 and 2.0 degrees C levels above pre-industrial ones. In particular, households are projected to experience 8% more air conditioning after surpassing the 1.5 degrees C threshold and up to 13% more after the 2.0 degrees C threshold, when compared to the baseline (2005-2019). We then discuss the implications of these projected changes on possible increase in air conditioner efficiency that would effectively counteract climate-induced increases. In the event that these climate-induced changes are not accounted for, we find that, in some states, the average household could face up to 14 days without air conditioning in a given summer in the 2.0 degrees C warmer world. This will disproportionately impact marginalized communities that are especially vulnerable to heat-related disasters and subsequent health impacts.