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Global Temperatures: Driven by ENSO?
Reference
McLean, J.D., de Freitas, C.R. and Carter, R.M. 2009. Influence of the Southern Oscillation on tropospheric temperature. Journal of Geophysical Research 114: 10.1029/2008JD011637.

What was done
The authors quantified "the effect of possible ENSO [El Niņo-Southern Oscillation] forcing on mean global temperature, both short-term and long-term," using the Southern Oscillation Index (SOI) provided by the Australian Government Bureau of Meteorology, which is "the standardized anomaly of the seasonal mean sea level pressure difference between Tahiti and Darwin, divided by the standard deviation of the difference and multiplied by 10." The temperature data used in this endeavor were "the University of Alabama in Huntsville (UAH) lower-tropospheric (LT) temperature data based on measurements from selected view angles of Microwave Sounding Unit (MSU) channel LT 2" for the period December 1979 to June 2008, supplemented by "balloon-based instrumentation (radiosondes)." More specifically, in the case of the latter data gong back in time to 1958, they employed the Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC) product (A) of the U.S. National Climatic Data Center, which represents the atmospheric layer between approximately 1500 and 9000 meters altitude.

What was learned
It was determined, in the words of McLean et al., that "change in SOI accounts for 72% of the variance in GTTA [Global Tropospheric Temperature Anomalies] for the 29-year-long MSU record and 68% of the variance in GTTA for the longer 50-year RATPAC record," as well as "81% of the variance in tropospheric temperature anomalies in the tropics," where ENSO "is known to exercise a particularly strong influence." In addition, they determined that "shifts in temperature are consistent with shifts in the SOI that occur about 7 months earlier."

What it means
The three researchers state, as their final conclusion, that "natural climate forcing associated with ENSO is a major contributor to variability and perhaps recent trends in global temperature, a relationship that is not included in current global climate models." We would only add that if this "major contributor" to global tropospheric temperature variability is truly "not included" in current global climate models, one would certainly have to question the validity of the output of those models, which form the sole basis for the fierce climate-alarmist attack on anthropogenic CO2 emissions.

Reviewed 5 August 2009