Wednesday, April 23, 2014

New paper finds natural Pacific Decadal Oscillation controlled Myanmar climate during 20th century

A paper published today in the International Journal of Climatology finds evidence of a strong influence of the natural Pacific Decadal Oscillation [PDO] on the climate of Myanmar over the 20th century. The authors reconstruct the Myanmar climate using tree ring data, producing another non-hockey-stick with temperatures warmer during the 1930's-1940s than at the end of the 20th century and end of the record in 2007. 

According to the authors, negative PDO phases correspond to dry conditions, due to reduced moisture flux into central Myanmar, and vice-versa. Many other peer-reviewed papers similarly demonstrate the major ocean oscillations are the primary "control knob" of climate, not CO2. 

It is well known that climate models are unable to reproduce any of the major ocean oscillations including the PDO, ENSO, AMO, etc., which is one of the primary reasons why climate models have little to no skill reproducing or projecting climate. 

The PDO, ENSO, AMO and other natural ocean oscillations have been linked to solar activity, and represent only one category of potential solar amplification mechanisms described in the scientific literature, and which continue to be ignored by climate modelers. 

Climate reconstruction from Teak tree rings shown in top graph demonstrates warmer temperatures during the 1930's-1940's than at the end of the record in 2007. Also shown is a close correspondence with the natural Pacific Decadal Oscillation in bottom graph 
Full paper available here

The climate of Myanmar: evidence for effects of the Pacific Decadal Oscillation

Rosanne D'Arrigo and Caroline C. Ummenhofer

We show evidence for the influence of the Pacific Decadal Oscillation (PDO) on Myanmar's monsoonal hydroclimate using both instrumental and 20th century reanalysis data, and a tree-ring width chronology from Myanmar's central Dry Zone. The ‘regime shifts’ identified in the instrumental PDO for the past century are clearly evident in the Myanmar teak. The teak record and PDO index correlate most significantly and positively during December–May, at r = 0.41 (0.002, n = 109). We generated composite climate anomalies for southern Asia and adjacent ocean areas during negative and positive PDO phases and above/below average teak growth for the May–September wet monsoon season. They show that negative (positive) PDO phases correspond to dry (wet) conditions, due to reduced (enhanced) moisture flux into central Myanmar. Multitaper Method (MTM) and Singular Spectrum Analysis (SSA) spectral analyses reveal considerable multidecadal variability over the past several centuries of the teak chronology, consistent with the PDO.

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