You’ve probably heard of El Niño, a weather phenomenon that has been in the news a great deal over the last decade.

During an El Niño event, slackening trade winds over the tropical Pacific trigger droughts in Australia, warmer waters off the coast of Peru, and a shift in storm patterns in North America.

El Niño (also known as the El Niño/ Southern Oscillation, or ENSO) is just one example of how variations in sea surface temperature have been correlated with dramatic changes in local, regional, and global weather patterns. The earth’s oceans absorb heat from sunlight, hold on to that heat, and—through the movement of ocean currents—transport it around the globe. Understanding the influence of ocean conditions on the earth’s climate, and monitoring changes in ocean conditions, are key to predicting climate change.