Intensification of Dangerous Heat Stress (IMAGE) Purdue University Caption This image represents intensification of dangerous heat stress in the 21st century. The color contours show the expected intensification of dangerous heat index days given accelerating increases in greenhouse gas concentrations. Credit Purdue University image/Diffenbaugh Laboratory 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.