Every three to seven years, for a period of anything from 6-18 months, the normal climatic pattern is dramatically disrupted. There is no 'sea of confusion' about temperature zones when El Niño swells into Galapagos waters. The sea becomes uniformly tropical, which for most creatures reliant on phytoplankton-rich oceans is a catastrophe of dire proportions. The cool Cromwell and Humboldt currents that nourish life vanish, replaced by warm, clear waters that are almost entirely devoid of phytoplankton. Starvation hits whole populations, often whole species, with astonishing mortalities. In the last 40 years there have been 5 big El Niño events in the Galapagos, the last one in 1997-8.