The Interdecadal Pacific Oscillation (IPO), a major atmospheric and meteorological pattern in the mid-Pacific Ocean, is now switching into a positive phase that will likely boost Pacific Ocean temperatures and accelerate global warming, according to new research.
Reporting in the journal Geophysical Research Letters, scientists at Melbourne University say that the IPO was in a negative phase from 2000 to 2014, which cooled sea surface temperatures in the Pacific and moderated global warming. The negative phase of the IPO, the paper said, served as a “temporary buffer” that “cushioned the impacts of global warming on extreme events, such as heatwaves.” Ben Henley, co-author of the paper, said in an interview, “The negative phase might have lulled us into a false sense of security — the planet appears temporarily to not be warming as fast.”
But shifts in mid-Pacific atmospheric and oceanic currents have now moved the IPO into a positive phase, meaning sea surface temperatures are expected to rise across a broad swath of the Pacific straddling the Equator. That, in turn, will drive up global temperatures — already setting records in recent years — to levels that by 2026 may well exceed a 1.5-degree C (2.7 F) increase over pre-industrial temperatures.
Changes in the IPO can influence Pacific Ocean temperatures in a band from 50 degrees north latitude to 50 degrees south, a significantly larger area than is affected by the better-known El Niño Southern Oscillation.