10.6  El Niño and La Niña

We conclude this study session by mentioning two natural climate cycles that can affect the location and frequency of extreme weather events around the world, including in Ethiopia. The rise in sea temperature that we described in Study Session 9 has widespread effects on ocean currents, particularly in the Pacific Ocean (National Weather Service, 2006). When the Pacific Ocean is unusually warm, it generates a climate cycle known as El Niño (‘little boy’ in Spanish); when the ocean temperature is unusually cool, the climate cycle is called La Niña (‘little girl’). El Niño and La Niña have opposite effects on the climate. Even though both of these ocean currents occur far away from Ethiopia, they influence the route and speed of major airstreams and alter the pattern of rainfall around the world, so that some regions are wetter than average and others are drier (Waskom et al., 2013).

The effects of El Niño and La Niña in Ethiopia depend on which of our two rainy seasons they occur in. The belg season is from February to March and the kirmit season is from June to September. If El Niño occurs during belg, it can cause above-normal rainfall, whereas if La Niña occurs during belg, it causes below-normal rainfall (FAO, 2014). In contrast, if El Niño occurs during kirmit, it decreases the seasonal rainfall, whereas La Niña during kirmit increases rainfall above the normal level (National Weather Service, 2006).

In the next study session, you will look in more detail at the impacts of climate change and extreme weather events on health, environments, agriculture, water resources and the Ethiopian economy.