Why? El Nino. The El Nino Southern Oscillation (ENSO) is a weather phenomenon in which hot water near Indonesia sloshes over to the coast of Peru. When this happens it dramatically boosts the average temperature of the global atmosphere. The highest global average temperature recorded in the past 150 years or so occurred during the big El Nino of 1998. On June 5, the National Oceanic and Atmospheric Administration's Climate Prediction Center issued a statement predicting that there is a 70 percent chance that an El Nino will emerge this summer, rising to an 80 percent chance that it will arrive by this fall and winter.
The U.N.'s Intergovernmental Panel on Climate Change 2013 Physical Sciences report issued last September acknowledged that global average temperatures during the past 16 years have not been increasing as the climate computer models projected that they should have done. Nevertheless, the IPCC report states that the current temperature slow-down will soon end and declares:
It is more likely than not that internal climate variability in the near-term will enhance and not counteract the surface warming expected to arise from the increasing anthropogenic forcing.
What sort of internal climate variability? A big El Nino would certainly do. In other words, when the warm-up resumes, IPCC predicts it will soar.
By how much? The IPCC report projects:
The global mean surface temperature change for the period 2016-2035 relative to 1986-2005 will likely be in the range of 0.3°C to 0.7°C.
This implies increases of 0.15°C to 0.35°C per decade. Keep in mind that the satellite data finds that the globe since 1979 has been warming at a rate of 0.14°C per decade.
Some climatologists speculate that a big El Nino could "flip" the Pacific Decadal Oscillation from its current cool phase to a warm phase, thus ending the temperature "hiatus." If the El Nino happens later this year, it's safe to predict that planet warming will pale in comparison to the heated rhetoric exchanged between climate "alarmists" and "deniers."
One short-term good could come of an El Nino—lots of rain for California and other parts of the parched Southwest.