What is La Nina?
La Nina is a climate pattern that describes the cooling of surface ocean waters along the tropical west coast of South America. It is considered to have the opposite effect of El Nino. It brings greater than normal rainfall in Southeast Asia and Australia, and causes drier-than-normal conditions in South
America and the Gulf Coast of the United States. La Nina events sometimes follow El Nino events.
What are El Nino’s ef ects?
El Nino affects global weather. It favours eastern Pacific hurricanes and tropical storms. Record and unusual rainfall in Peru, Chile and Ecuador are linked to the climate pattern. El Nino reduces upwelling of cold water, decreasing the uplift of nutrients from the bottom of the ocean. This affects marine
life and sea birds. The fishing industry is also affected.
Drought caused by El Nino can be widespread, affecting southern Africa, India, Southeast Asia,Australia, and the Pacific Islands. Countries dependent on agriculture are affected. Australia and Southeast Asia get hotter. A recent WHO report on the health consequences of El Nino forecasts a rise in vector-borne diseases, including those spread by mosquitoes, in Central and South America.
What causes El Nino?
El Nino sets in when there is anomaly in the pattern. The westward-blowing trade winds weaken along the Equator and due to changes in air pressure, the surface water moves eastwards to the coast of
northern South America. The central and eastern Pacific regions warm up for over six months and result in an El Nino condition. The temperature of the water could rise up to 10 degrees Fahrenheit above normal.
