No Global Warming For Maybe Another Decade

Average global temperatures have been
essentially flat for nearly the past 17 years, even as
heat-trapping carbon dioxide from burning fossil fuels has
accumulated in the atmosphere. Now a new study
published in Science reports that the current “pause” in
man-made global warming is the result of currents in the North
Atlantic burying the extra heat in the deep ocean. The researchers
postulate that this phenomenon flips back and forth between hot and
cold phases every 20 to 35 years. When it flips out of the current
cold phase, average temperatures will begin to rise steeply.

The BBC reports:

The researchers say that there was another hiatus between 1945
and 1975 due to this current taking down the heat, that led to
fears of a new ice age.

From 1976 though, the cycle flipped and contributed to the
warming of the world, as more heat stayed on the surface.

But since the year 2000, the heat has been going deeper, and the
world’s overall temperatures haven’t risen beyond the
record set in 1998. …

A key element in this new understanding is the saltiness of the
water. The waters in the Atlantic current coming up from the
tropics are saltier because of evaporation. This sinks more quickly
and takes the heat down with it.

Eventually though, the salty water melts enough ice in Arctic
waters to lower the saline level, slowing down the current and
keeping the heat near the surface.

“Before 2006 the saltiness was increasing, this indicated that
the current was speeding up,” said  [principal researcher]
Prof [Ka-Kit] Tung [from the University of Washington].

“After 2006, this saltiness is diminishing but it’s still above
the long-term average. Now it is slowly slowing down.

“Once it gets below the long-term average, then it is the next
period of rapid warming.” …

“We probably may have another 10 years, maybe shorter as global
warming itself is melting more ice and ice could flood the North
Atlantic, but historically we are in the middle of the cycle.”

The U.N Intergovernmental Panel on Climate Change 2013
Physical Sciences report suggests that the current temperature
slow-down will soon end and states, “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.” In other words, when
the warm-up resumes 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.

Hat tip Ken Constantino.