Extreme Weather Event Warming Signals (IMAGE) Arizona State University Caption Early warning signals as increasing autocorrelation coefficient and standard deviation prior to the early 20th century global warming (left) and mega heat wave during 2010 in Russia (right). Credit Chenghao Wang, Stanford University 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.