Working with 2249 globally-distributed monthly temperature records covering the period 1906-2005, which they obtained from NASA’s Goddard Institute for Space Studies, Ludecke et al. (2011) evaluated “to what extent the temperature rise in the past 100 years was a trend or a natural fluctuation.”
Based on their several findings, the authors write in the final sentence of the abstract of their paper that the strongest statement they can make on the subject is that “only a marginal anthropogenic contribution cannot be excluded,” which suggests to us that if there is a CO2-induced warming signal hidden somewhere in the global temperature data of the Goddard Institute for Space Studies, it must be relatively small, as is suggested by the observation-based analyses of Idso (1998), Lindzen and Choi (2009, 2011) and Scafetta (2012).
