Scientists in Hawaiʻi have discovered a critical flaw in the global method used to measure demand for air conditioning. The traditional indicator fails to account for humidity, a key factor in cooling system efficiency. A study published in *Nature Communications* reveals that cooling system efficiency has declined by 2-4% per decade since 1971. This decline, linked to increasing humidity, has remained undetected by current measurement tools. Researchers emphasize that accurately gauging air conditioning demand is vital for predicting future energy consumption and planning infrastructure. Failing to account for humidity leads to an underestimation of cooling needs and potential energy grid strain. The findings highlight the need for revised measurement methods that incorporate humidity levels for more accurate assessments.