We use statistical methods for nonstationary time series to test the anthropogenic interpretation of global warming (AGW), according to which an increase in atmospheric greenhouse gas concentrations raised global temperature in the 20th century. Specifically, the methodology of polynomial cointegration is used to test AGW since during the observation period (1880–2007) global temperature and solar irradiance are stationary in 1st differences whereas greenhouse gases and aerosol forcings are stationary in 2nd differences. We show that although these anthropogenic forcings share a common stochastic trend, this trend is empirically independent of the stochastic trend in temperature and solar irradiance. Therefore, greenhouse gas forcing, aerosols, solar irradiance and global temperature are not polynomially cointegrated. This implies that recent global warming is not statistically significantly related to anthropogenic forcing. On the other hand, we find that greenhouse gas forcing might have had a temporary effect on global temperature. (Emphasis added.)
This is a stronger claim than made by Roger Pielke, Sr., in his discussion of the game-changer papers of last summer. In that case, Pielke claimed that while warming is real, and CO2 a contributor to it, the warming is not as rapid as alarmists claim, and CO2 not as large a contributor as advertised, either.
The last claim, that greenhouse gases may have had a temporary effect on temperature makes perfect sense, if you believe that a biological system can adapt in response to a changing input. It might just take a little time to adjust.
The study comes out of Israel, which will no doubt give the Left another reason to hate both the study and the country that produced it.