Pick Our Brain - December 2009

How did the El Niño and La Niña climate phenomena get their names? Are there other climate systems important to California water and ecosystems?

El Niño translates as “the little boy” or “the Christ child” in Spanish. The name was given to unusually warm water in the eastern tropical Pacific by fishermen off the coast of South America. The tendency of the phenomenon to arrive around Christmas was the origin of the name. This climate phenomenon is now understood to have global implications that extend far from the western coast of South America. The flip side of the El Niño phenomenon is a cooling of the waters in the eastern tropical Pacific. Early on this was called an “anti-El Niño,” but the literal translation of “anti-Christ” made the preferred name become La Niña or “the little girl.” La Niña too has global weather affects. In California, El Niño generally produces wetter winter and spring conditions and La Niña brings drier winter and spring conditions, particularly in southern California.

There are other sources of climate variability that are important to California. The Pacific Decadal Oscillation (PDO) is a measure of temperature variability in the north Pacific with variations in the northeast Pacific particularly important to the strength of salmon runs in northern California, the Pacific Northwest, and Alaska. This climate system generally operates at longer time periods than El Niño and La Niña and has effects on the time scale of decades as the name suggests. Another new identified pattern of climate variability is the North Pacific Gyre Oscillation (NPGO). This system appears to have a significant effect on the salinity, nutrients, and algae of coastal California. The fluctuations reflect changes in the intensity of circulations in the North Pacific gyre. Recent research has shown a strong link between the status of NPGO and fish and crab populations in San Francisco Bay.

Changing climate patterns in the Pacific Ocean have clear effects on California precipitation and our aquatic ecosystems. Tracking these climate systems has become an important tool in forecasting seasonal weather conditions and the population dynamics of many of our fish, birds, and marine mammals.

Sea surface temperatures in the Southern Pacific - graphic courtesy of NOAA
Sea surface temperatures in the Southern Pacific - graphic courtesy of NOAA