Evaluating effectiveness of impact-based heatwave warnings for perceptions and risk-mitigating behaviors: Survey studies in South Korea

Excessive heat is a serious health hazard across the globe, and heat-related risks may continue to rise due to climate change. Impact-based warning (IBW) systems that provide information on the expected consequences of an impending weather event have the potential to reduce heat-related illness and death by allowing for adequate public responses and decision-making. This research evaluated the effectiveness of heatwave IBWs in South Korea, where heat is the leading cause of weather-related deaths. Two survey studies were conducted with nationally representative samples using actual heatwave warnings issued to the public. In Study 1, participants received either an IBW or a conventional phenomenon warning for a hypothetical scenario for a heatwave scenario with varying risk levels. IBWs were found to improve the perceived threat of the heatwave risk and credibility of the warned impacts, particularly for high-risk heatwaves, but did not lead to higher intentions to take risk-mitigating behaviors. Perceptions were positively associated with behavioral intention, suggesting that IBWs may still indirectly influence risk-mitigating behaviors. In Study 2, where real-time warnings were presented to participants during a low-risk heatwave, no differences in perceptions or behavioral intentions were found between the two warning types. Age and prior heatwave experience were associated with increased risk perception and behavioral intention but did not influence the effects of IBWs. These findings suggest that IBWs can be effective in enhancing risk perception, particularly under higher-risk conditions, but may have limited influence on behavioral responses.