Trajectories toward the 1.5°C Paris target: Modulation by the Interdecadal Pacific Oscillation

The 1.5°C target will be breached before 2029.
Global  is rapidly approaching the 1.5°C Paris target. In the absence of external cooling influences, such as volcanic eruptions,  projections are centered on a breaching of the 1.5°C target, relative to 1850-1900, before 2029. The phase of the Interdecadal Pacific Oscillation (IPO) will regulate the rate at which mean  approaches the 1.5°C level. A transition to the positive phase of the IPO would lead to a projected exceedance of the target centered around 2026. If the Pacific Ocean remains in its negative decadal phase, the target will be reached around 5 years later, in 2031. Given the temporary slowdown in global warming between 2000 and 2014, and recent initialized decadal predictions suggestive of a turnaround in the IPO, a sustained period of rapid  rise might be underway. In that case, the world will reach the 1.5°C level of warming several years sooner than if the negative IPO phase persists.
Source: Geophysical Research Letters
URL:     http://onlinelibrary.wiley.com/doi/10.1002/2017GL073480/full
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