El Nino comparison. Maps comparing Pacific Ocean heights on 2nd May 1997 (left) and 3rd May 2014. Blue areas are lower than average and brown areas are higher than average. Water expands as it warms and so warm areas of the ocean are higher than cool areas. The dark brown areas across centre are indicative of 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. May 1997 was one of the most powerful El nino events of the 20th century. 1997 data obtained by the TOPEX/Poseidon satellite, 2014 data obtained by the Ocean Surface Topography Mission (OSTM)/Jason-2 satellite.