El Niño has arrived, replacing the La Niña weather patterns experienced in New Zealand for the past three years. This change brings cooler weather due to a switch in wind direction. The specific details of this El Niño are still unknown.
There have been signs of El Niño's arrival for a while. Last year, underwater temperatures showed warm water building up in the Coral Sea and western tropical Pacific, indicating its approach. When La Niña ended in March of this year, global sea surface temperatures reached record highs as the tropical Pacific warmed rapidly.
The high North and South Pacific sea surface temperatures, influenced by La Niña and global warming, caused "atmospheric rivers" that brought heavy rains to California and New Zealand. Comparing temperature changes from December 2022 to May 2023 reveals significant shifts in sea surface temperatures, including a noticeable El Niño off the coasts of Peru and Ecuador.
El Niño-Southern Oscillation (ENSO) is a combination of atmospheric and oceanic phenomena that affects the tropical Pacific. La Niña represents cooling across the Pacific, while El Niño is a warm phase occurring every three to seven years. El Niños can be intense and uncommon, while La Niñas are usually moderate and more frequent. El Niños typically peak in December, significantly impacting the atmosphere in February. The last major El Niño happened in 2016-17, with a weak one in 2019-20.
El Niño and La Niña are part of the ENSO system that influences global weather patterns. The atmosphere and ocean are connected in the tropical Pacific, with surface winds driving ocean currents and sea surface temperatures affecting winds. El Niño involves the transfer of heat from the ocean to the atmosphere, which changes rainfall patterns and affects jet streams and storm tracks worldwide.
While climate change has not directly affected ENSO events, it exacerbates the impacts of El Niño. Extreme weather events like floods and droughts, already associated with ENSO, become more severe. El Niño disrupts agriculture, fisheries, health, energy demand, and air quality due to wildfires. It is the primary cause of droughts worldwide and increases wildfire risks in regions like Australia, Indonesia, and Brazil. Peru, Ecuador, and sometimes California and the southeastern United States experience heavy rainfall and flooding during El Niño.
El Niño has significant social and economic impacts, causing disruptions in various sectors and countries. Economic growth is consistently reduced during El Niño events, with damages amounting to trillions of US dollars. Droughts, floods, heat waves, and changes in air quality severely impact societies and economies worldwide.
In summary, the arrival of El Niño in New Zealand brings cooler conditions due to a shift in wind patterns. El Niño's effects are felt globally, affecting rainfall, jet streams, and storm tracks. While climate change doesn't directly influence ENSO events, it intensifies the impacts of El Niño, resulting in more extreme weather phenomena. The social and economic consequences of El Niño are substantial, causing disruptions in agriculture, fisheries, health, energy demand, and air quality.