Wherefore art thou Niño?

Wherefore art thou Niño?

Posted on Climate Change, August 22, 2009

This essay addresses the question of whether tropical waters are likely to warm or cool in the last half of 2009. Necessarily it also addresses matters such as:

• The character of warming cycles in the tropics.
• The usefulness of the ENSO 3.4 Index as a proxy for tropical warming events.
• The driver of sea surface temperature change in the tropics.
• Change in the nature of this driver over time.
• The contribution of warming cycles in the tropics to global temperature change.
• The place of greenhouse theory in explaining global temperature change.

For a description of the data used for this analysis see Kalnay, E. and Coauthors, 1996: The NCEP/NCAR Reanalysis 40-year Project. Bull. Amer. Meteor. Soc., 77, 437-471. This data can be accessed at: http://www.cdc.noaa.gov/cgi-bin/data/timeseries/timeseries1.pl

Global temperature is strongly influenced by change in sea surface temperature in the global tropics. There is a lag of about six months from tropical to global peak. There is no argument as to the driver of global temperature on a year to year basis. Until recently many observers (including the UNIPCC) have maintained (without any justification whatsoever) that the ENSO oscillation is temperature neutral on decadal and longer time scales. That assertion is now widely questioned. We must ask how much, and whether all of the change in global temperature can be attributed to the cycles of warming and cooling in the tropics. The strong temperature gain between 1978 and 1998 has been attributed to man’s influence on the basis that “we know of no other reason for the change that has been observed.” That logic is now in question. Was something really obvious simply overlooked? There is still no evidence for the greenhouse induced ‘hot spots’ in the upper atmosphere. Is the UNIPCC assertion that the recent warming is due to the activities of man classic case of jumping to premature conclusions in the face of abundant evidence to the contrary.

Frequently the collapse of a solar cycle is associated with cooling in the tropics while the onset of a new cycle is associated with the initiation of a strong warming event. However, Cycle 24 is unusual. The sun is spotless even though 10.7cm radio flux has been increasing since late 1998. Just when is the big warming event to be expected and will it be as big as 1997-8?

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