Cool Roofs (IMAGE) DOE/Lawrence Berkeley National Laboratory Caption In this study, a heat wave consists of at least three consecutive days with maximum air temperature of 35 C or higher. The simulation above illustrates the extent to which cool roofs could reduce annual population exposure to heat waves in Northern and Southern California in mid-century under hot and warm scenarios, driven by high greenhouse gas emissions and more modest emissions, respectively. Credit Berkeley Lab Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.