Corals show how El Nino is intensifying as the planet warms

A new study published in Science reveals that El Nino episodes are becoming more intense as global temperatures rise, with implications for the future under climate change. The research, led by Professor Julia Cole of the University of Michigan, analyzed coral skeleton records dating back 1,000 years from the Galapagos Islands, located in the heart of the eastern Pacific El Nino zone.

By examining the chemical composition of the coral growth rings, the scientists were able to reconstruct monthly temperature records spanning the past millennium.

The study found that the swings associated with El Nino cycles were significantly smaller during the preindustrial period (1000-1850), but began to increase in the late 19th century and show "striking amplification" over the last 40 years. These changes in El Nino intensity align with global warming, suggesting a relationship between the warming of the planet caused by human activities and the strengthening of El Nino events.

The findings indicate that ENSO variability, or the fluctuations between El Nino and La Nina episodes, is now roughly 36% greater in the equatorial eastern Pacific Ocean compared to preindustrial times. This amplification is largely due to stronger El Ninos, which are pushing the ocean-atmosphere system to greater extremes. While the research does not propose specific physical mechanisms for the observed changes, it fills an important gap in understanding how a warming world is impacting El Nino.

The study's lead author emphasized the urgent need to transition away from fossil fuels and towards climate-safe renewable energy sources, given the immense implications of the intensified El Nino events for extreme weather hazards worldwide.