Nicola Scafetta has reminded me to revisit his global average surface temperature (GST) forecast (Cyan area), which he derived from a simple phenomenological model using solar system planetary frequencies at the start of 2012. It is clearly much more accurate than the IPCC projection from 2000 (shown in Green on the figure below).
See below the break for more information on the Solar-Planetary Theory Nicola used.
The basic harmonic model referring to the global temperature is based on just four astronomical cycles (periods: ~9.1(lunar), ~10.5(Solar), ~20(Jovian) and ~60 year (Jovian cycle)) against the global surface temperature since 1950 and the general circulation model (GCM) simulations adopted by the IPCC under different emission scenarios. In Figure 6 the global surface temperature (HadCRUT3) is updated in the blue curve; the back curve within the cyan area is a full model forecast since 2000 that clearly outperforms the IPCC general circulation model projections (green area). The IPCC predicted a significant increase of the temperature that has not been observed since 2000.
A longer article covering the subject can be found in the lower half of Nicola’s personal page at Duke University