Recent cooler temperatures were predictable
It is likely that 2011 will be the coolest year globally since 1956 or even earlier, according to the New Zealand
Climate Science Coalition. Global temperatures in February just past continued to fall in a manner consistent with the
findings of a peer reviewed paper by John McLean, Professor Chris de Freitas and Professor Bob Carter that was published
in 2009.
The paper showed that the Southern Oscillation Index (SOI), a measure of El Nino-Southern Oscillation (ENSO) conditions,
is a very good indicator of average global atmospheric temperatures seven months ahead, except when sporadic volcanoes
caused short-term cooling.
"The global cooling that started in October 2010 is merely a reflection of the La Nina conditions that began last
April," says Mr McLean, "and the delay means that the average annual temperature in 2010 was due to the warm El Nino
conditions that preceded the switch."
The Coalition says several previous scientific papers have discussed the delayed response, including two by critics of
McLean's paper. Although the other papers used different data sources they came to similar conclusions about the delay.
“The key question is how much influence the ENSO has on average global temperature. Although this can be difficult to
determine because both can be affected by short term events such as wind, clouds and tropical storms, the sustained
relationship in the data of the last 50 years shows the effect is significant,” says Mr McLean.
“The historical data also casts serious doubt on the hypothesis that carbon dioxide causes dangerous global warming.
Since 1958 there's been a 30% increase in atmospheric carbon dioxide. If this had a major influence on temperature we'd
expect to see clear evidence of the temperature line rising relative to the SOI line, which is not apparent".
“The Australian Bureau of Meteorology reports that ENSO models are suggesting that the La Nina will continue well into
the Southern Hemisphere autumn and fade slowly to neutral conditions by June. Taking into account the seven-month time
lag it is likely that 2011 will be the coolest year since 1956 or even earlier. Also, records show the oceans absorb
more carbon dioxide during a La Nina event than during an El Nino, which means that the increase in atmospheric carbon
dioxide in 2011 is likely to be less than in recent years," Mr McLean concludes.
More Information:
Small image - http://mclean.ch/Graph_SOI_Temp_small.bmp
Larger image - http://mclean.ch/Graph_SOI_Temp_large.bmp
Suggested image caption - http://mclean.ch/Graph_SOI_Temp_caption.txt
Further background, incl. discussion of criticism of two sentences in the less important part of the paper:
Ends