What was done
The authors "review physical and biological fluctuations with periods of about 50 years that are particularly prominent in the Pacific Ocean."  Parameters studied include air and ocean temperatures, atmospheric CO2 concentration, landings of anchovies and sardines, and the productivity of coastal and open ocean ecosystems.

What was learned
The authors find that "sardine and anchovy fluctuations are associated with large-scale changes in ocean temperatures: for 25 years, the Pacific is warmer than average (the warm, sardine regime) and then switches to cooler than average for the next 25 years (the cool, anchovy regime."  They also report that "instrumental data provide evidence for two full cycles: cool phases from about 1900 to 1925 and 1950 to 1975 and warm phases from about 1925 to 1950 and 1975 to the mid-1990s."  These warm and cool regimes, which they respectively call El Viejo (the old man) and La Vieja (the old woman), are manifest in myriad similar-scale biological fluctuations that may be even better indicators of climate change than climate data themselves, according to the authors.

What it means
The findings of this important study have many ramifications.  The one that we highlight is the challenge the new results present for the detection of CO2-induced global warming.  The authors correctly note, for example, that data used in climate change projections are "strongly influenced by multidecadal variability of the sort described here, creating an interpretive problem."  Hence, they conclude that "these large-scale, naturally occurring variations must be taken into account when considering human-induced climate change."

In this regard, we note that the warming of the late 1970s to late 1990s, which returned much of the world to the level of warmth experienced during the 1930s and 1940s, may well be about to end.  In fact, Chavez et al. cite much evidence that indicates a change from El Viejo to La Vieja conditions may already be in progress.  If this is indeed true, we could well see global temperatures begin to drop in the very near future.

We also note that the authors remarks about "large-scale, naturally occurring variations" needing to be considered when looking for "human-induced climate change" apply equally well to the millennial-scale climatic oscillation that brought our planet the Roman Warm Period, the Medieval Warm Period and now, very likely, the Modern Warm Period, which is something climate alarmists seem especially loath to do.