Wyatt et al. published an interesting paper which shows in essence that natural oscillations define the North Hemisphere Temperature (NHT): no need to look for CO2 or other AGHG, natural variability is the Occam razor. See poster here.
North Hemisphere Temperature = blue curve. 0.83*AMO+0.44*PDO = red broken lcurve; both are nearly identical!
Joseph d’Aleo and Don Easterbrook did the same for US temperatures in a paper published Sep. 2010 in Energy & Environnement:
So we now have 2 independent papers, each covering a different region of the globe, and each coming to the same conclusion: temperature is driven by oceanic oscillations (which may themselves represent the influence of changing cloud cover and solar activity).