El Niño All the Time

If history repeats itself, global warming could create a lasting shift in Pacific ocean circulations

EL NIÑO, the change in ocean circulation that typically occurs in the Pacific every 4 to 12 years, causes all kinds of trouble: flooding, drought, unseasonable weather. New research indicates that if history repeats itself, global warming could create permanent El Niño-like conditions in the Pacific. Researchers from the University of California–Santa Cruz studied the chemical makeup of microscopic shells from the Pliocene era—5 million to 1.7 million years ago—the last time that Earth’s climate was warmer than it is today. The composition of those shells shows that the ocean’s temperature variation during the Pliocene was similar to the Pacific during El Niño years.