Developing El Nino, April 2023. Globe showing central and Pacific Ocean height on 34th April 2023. Purple and blue areas are lower than average, normal sea levels are green and yellow and red areas are higher than average. Water expands as it warms and so warm areas of the ocean are higher than cool areas. The red area across centre is indicative of Kelvin waves pushing warmer water westwards towards the coasts of Peru, Ecuador, and Columbia. Such waves are a precursor to an El Nino event. El Nino effects weather systems across the world, causing drier conditions in Australia and South-East Asia, and wetter and warmer conditions in the Americas, with often dire effects for agriculture. Image obtained by the Sentinel-6/Michael Freilich satellite.