Earth is Experiencing a Global Warming Spurt
Cyclical changes in the Pacific Ocean have thrown earth’s surface into what may be an unprecedented warming spurt, following a global warming slowdown that lasted about 15 years.
While El Niño is being blamed for an outbreak of floods, storms and unseasonable temperatures across the planet, a much slower-moving cycle of the Pacific Ocean has also been playing a role in record-breaking warmth. The recent effects of both ocean cycles are being amplified by climate change.
A 2014 flip was detected in the sluggish and elusive ocean cycle known as the Pacific Decadal Oscillation, or PDO, which also goes by other names, including the Interdecadal Pacific Oscillation. Despite uncertainty about the fundamental nature of the PDO, leading scientists link its 2014 phase change to a rapid rise in global surface temperatures.
The effects of the PDO on global warming can be likened to a staircase, with warming levelling off for periods, typically of more than a decade, and then bursting upward.
“It seems to me quite likely that we have taken the next step up to a new level,” said Kevin Trenberth, a scientist with the National Centre for Atmospheric Research.
The 2014 flip from the cool PDO phase to the warm phase, which vaguely resembles a long and drawn out El Niño event, contributed to record-breaking surface temperatures across the planet in 2014.
The record warmth set in 2014 was surpassed again in 2015, when global temperatures surged to 1°C (1.8°F) above pre-industrial averages, worsening flooding, heatwaves and storms.
The effects of the warm phase of the PDO and the current El Niño may be cumulative in terms of warming the planet. It also seems likely that changes in the ocean cycles are linked, with changes between El Niño and La Niña driving changes in the PDO cycle.
Cold PDO phases have a blue background; warm phases are red.