More than a hint of assuming what they would like to prove here, by implying El Niños are now influenced by ‘the industrial age’. But at the end of the report a researcher says: “Maybe El Niño can just enter a mode and get stuck in it for a millennium.” Who gets to define what is or isn’t ‘natural variation’?

El Niños have become more intense in the industrial age, which stands to worsen storms, drought, and coral bleaching in El Niño years, reports Phys.org.

A new study has found compelling evidence in the Pacific Ocean that the stronger El Niños are part of a climate pattern that is new and strange.

It is the first known time that enough physical evidence spanning millennia has come together to allow researchers to say definitively that: El Niños, La Niñas, and the climate phenomenon that drives them have become more extreme in the times of human-induced climate change.

“What we’re seeing in the last 50 years is outside any natural variability. It leaps off the baseline. Actually, we even see this for the entire period of the industrial age,” said Kim Cobb, the study’s principal investigator and professor in the Georgia Institute of Technology’s School of Earth and Atmospheric Sciences.

“There were three extremely strong El Niño-La Niña events in the 50-year period, but it wasn’t just these events. The entire pattern stuck out.”

The study’s first author Pam Grothe compared temperature-dependent chemical deposits from present-day corals with those of older coral records representing relevant sea surface temperatures from the past 7,000 years.

With the help of collaborators from Georgia Tech and partner research institutions, Grothe identified patterns of in the El Nino Southern Oscillation (ENSO), swings of heating and cooling of equatorial Pacific waters that, every few years, spur El Niños and La Niñas respectively.

The team found the industrial age ENSO swings to be 25% stronger than in the pre-industrial records. The researchers published their results in the journal Geophysical Review Letters in October 2019. The work was funded by the National Science Foundation.

Slumbering evidence

The evidence had slumbered in and around shallow Pacific waters, where ENSO and El Niños originate until Cobb and her students plunged hollow drill bits into living coral colonies and fossil coral deposits to extract it. In more than 20 years of field expeditions, they collected cores that contained hundreds of records.

The corals’ recordings of sea surface temperatures proved to be astonishingly accurate when benchmarked. Coral records from 1981 to 2015 matched sea surface temperatures measured via satellite in the same period so exactly that, on a graph, the jagged lines of the coral record covered those of the satellite measurements, obscuring them from view.

Continued here.

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November 23, 2019 at 04:21AM