Study: Ocean net heat flow is connected with climate shifts – CO2 not correlated
– no “warming in the pipeline”
Related to this story: The Pacific Decadal Oscillation Time Series from the University
of Washington, seen below. Emphasis points mine. h/t to WUWT reader Richard Heg.
Monthly Values for the PDO Index, January 1900 to September 2008. Positive (red)
index values indicate a warm phase PDO; negative (blue) index values indicate a cool
phase PDO. While short-term flips in PDO phases do occur, evaluation of 20th century
instrumental records has shown that PDO phases generally persist for 20-30 years,
as indicated in this figure. To download the data, see Nate Mantua’s PDO page.
Changes in Net Flow of Ocean Heat Correlate with Past Climate Anomalies
Physicists at the University of Rochester have combed through data from satellites
and ocean buoys and found evidence that in the last 50 years, the net flow of heat
into and out of the oceans has changed direction three times.
These shifts in the balance of heat absorbed from the sun and radiated from the oceans
correlate well with past anomalies that have been associated with abrupt shifts in
the earth’s climate, say the researchers. These anomalies include changes in normal
storm intensities, unusual land temperatures, and a large drop in salmon populations
along the western United States.
The physicists also say these changes in ocean heat-flow direction should be taken
into account when predicting global climate because the oceans represent 90 percent
of the total heat in the earth’s climate system.
The study, which will appear in an upcoming issue of Physics Letters A, differs from
most previous studies in two ways, the researchers say. First, the physicists look
at the overall heat content of the Earth’s climate system, measuring the net balance
of radiation from both the sun and Earth. And second, it analyzes more completely
the data sets the researchers believe are of the highest quality, and not those that
are less robust.
“These shifts happened relatively abruptly,” says David Douglass, professor of physics
at the University of Rochester, and co-author of the paper. “One, for example, happened
between 1976 and 1977, right when a number of other climate-related phenomenona were
happening, such as significant changes in U. S. precipitation.”
Douglass says the last oceanic shift occurred about 10 years ago, and that the oceans
are currently emitting slightly more radiation than they are receiving.
The members of the team, which includes Robert Knox, emeritus professor of physics
at the University, believe these heat-flux shifts had previously gone unnoticed because
no one had analyzed the data as thoroughly as the Rochester team has.
The team believes that the oceans may change how much they absorb and radiate depending
on factors such as shifts in ocean currents that might change how the deep water
and surface waters exchange heat. In addition to the correlation with strange global
effects that some scientists suspect were caused by climate shifts, the team says
their data shows the oceans are not continuously warming—a conclusion not consistent
with the idea that the oceans may be harboring “warming in the pipeline.” Douglass
further notes that the team found no correlation between the shifts and atmospheric
carbon dioxide concentration.
“An interesting aspect of this research is that no reference to the surface temperature
itself is needed,” says Knox. “The heat content data we used, gathered by oceanographers,
was gleaned from temperature measurements at various ocean depths up to 750 meters.”
The team also found that the radiative imbalance was sufficiently small that it was
necessary to consider the effect of geothermal heating. Knox believes this is the
first time this additional source of heat has been accounted for in such a model.
The team notes that it’s impossible to predict when another shift might occur, but
they suspect future shifts might be similar to the three observed. Both Douglass
and Knox are continuing to analyze various climate-related data to find any new information
or correlations that may have so far gone unnoticed.