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Limits on CO2 Climate Forcing from Recent Temperature Data
David Douglass and John Christy have a new paper accepted in the refereed section of the journal Energy & Environment, which is also available as an arXiv pre-print. It’s unusual for either John Christy or David Douglass to submit a paper to E & E, which doesn’t appear in any citation index. On the other hand, it is unlikely that Christy would put his name to a paper that is fundamentally flawed.
The paper is entitled: ‘Limits on CO2 Climate Forcing from Recent Temperature Data of Earth’
The Abstract States:
The global atmospheric temperature anomalies of Earth reached a maximum in 1998 which has not been exceeded during the subsequent 10 years. The global anomalies are calculated from the average of climate effects occurring in the tropical and the extratropical latitude bands. El Niño/La Niña effects in the tropical band are shown to explain the 1998 maximum while variations in the background of the global anomalies largely come from climate effects in the northern extratropics. These effects do not have the signature associated with CO2 climate forcing. However, the data show a small underlying positive trend that is consistent with CO2 climate forcing with no-feedback.
Summary:
The recent atmospheric global temperature anomalies of the Earth have been shown to consist of independent effects in different latitude bands. The tropical latitude band variations are strongly correlated with ENSO effects. The maximum seen in 1998 is due to the El Niño of that year. The effects in the northern extratropics are not consistent with CO2 forcing alone
An underlying temperature trend of 0.062±0.010ºK/decade was estimated from data in the tropical latitude band. Corrections to this trend value from solar and aerosols climate forcings are estimated to be a fraction of this value. The trend expected from CO2 climate forcing is 0.070g ºC/decade, where g is the gain due to any feedback. If the underlying trend is due to CO2 then g~1. Models giving values of g greater than 1 would need a negative climate forcing to partially cancel that from CO2. This negative forcing cannot be from aerosols.
These conclusions are contrary to the IPCC [2007] statement: “[M]ost of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.”