Schematic of Pacific Walker Circulation Changes (image) Institute for Basic Science Share Print E-Mail Caption Normal conditions (top), strengthening due to natural variability (middle) and weakening due to greenhouse warming (bottom). Black arrows represent horizontal and vertical winds with the shading on the background map illustrating ocean temperatures. Over the past few decades, natural variability has strengthened the Pacific Walker circulation leading to enhanced cooling in the equatorial central-to-eastern Pacific (middle). Climate models forced by increasing greenhouse gas concentrations simulate weakening of the Walker circulation (bottom). (Right) Temporal evolution of model-simulated Walker circulation trends, with the dark blue line and orange shading denoting anthropogenically-induced changes and the impact of natural processes, respectively. Credit IBS Usage Restrictions Please indicate IBS as the credit of the image. Share Print E-Mail 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.