- The de Vries solar cycle together with the AMO/PDO are sufficient to explain the main climate variations of the last 1000 years
- It is unnecessary to invoke carbon dioxide and its effects to explain the climate cycles
- The 21st century will see an underlying cooling due to the de Vries cycle and then modulated by the AMO/PDO.
The 200-210 year de Vries solar cycle (also known as the Suess cycle) has been postulated for some time (here and here for example) as being one of the main natural cycles governing our climate. The effect of the de Vries cycle can be traced back through the glacial record through many millenia and even through geologic ages. Many solar effects work on climate through ocean cycles. The Atlantic/Pacific Oscillations are well known as drivers of climate and can be traced back through at least about 1500 years. The Atlantic Multidecadal Oscillation (AMO) has a period of about 66 years while the Pacific Decadal Oscillation (PDO) has a slightly shorter cycle of 60 years.
The entire hypothesis that carbon dioxide concentrations in the atmosphere and therefore human emissions of carbon dioxide are responsible for “global warming” is based on the argument that nothing else can explain the warming witnessed during the 20th century. Yet this is not just conjecture it is a fantasy based on ignoring the effect of the natural cycles that are known to exist. In fact there is no need to invoke carbon dioxide concentration to explain the ups and down of climate. German researchers have now shown that just the de Vries Cycle together with the AMO and the PDO are quite sufficient. The period in the 1970′s and 1980′s often used as the foundation for “global warming” theory can be quite sufficiently explained by the AMO/PDO.
Just as we had about 100 years of an underlying warming due to the de Vries cycle in the 20th century, we are in for an underlying cooling through the 21st century in response to the de Vries solar cycle. This underlying trend will be modulated by the ups and downs of the AMO and the PDO. Carbon dioxide concentrations are largely irrelevant.
The following is from an article at NoTricksZone:
by Prof. H. Luedecke and C.O. Weiss (Original German version here).
We reported recently about our spectral analysis work of European temperatures  which shows that during the last centuries all climate changes were caused by periodic (i.e. natural) processes. Non-periodic processes like a warming through the monotonic increase of CO2 in the atmosphere could cause at most 0.1° to 0.2° warming for a doubling of the CO2 content, as it is expected for 2100.
Fig. 1 (Fig. 6 of  ) shows the measured temperatures (blue) and the temperatures reconstructed using the 6 strongest frequency components (red) of the Fourier spectrum, indicating that the temperature history is determined by periodic processes only.
On sees from Fig. 1 that two cycles of periods 200+ years and ~65 years dominate the climate changes, the 200+ year cycle causing the largest part of the temperature increase since 1870.
The ~65 year cycle is the well-known, much studied, and well understood “Atlantic/Pacific oscillation” (AMO/PDO). It can be traced back for 1400 years. The AMO/PDO has no external forcing it is “intrinsic dynamics”, an “oscillator”.
Although the spectral analysis of the historical instrumental temperature measurements  show a strong 200+ year period, it cannot be inferred with certainty from these measurements, since only 240 years of measurement data are available. However, the temperatures obtained from the Spannagel stalagmite show this periodicity as the strongest climate variation by far since about 1100 AD.
The analysis of solar activity proves the existence and the strength of the 200+ year periodicity which we found from historical temperature measurements, as well as from the Spannagel stalagmite data. This 200+ year cycle is apparently the one known as “de Vries cycle”.
This solar “de Vries cycle together with the AMO/PDO determine practically completely the global climate of the past (Fig. 1) and the coming time. A significant influence of CO2 on the climate thus has to be excluded. This latter is not surprising in view of the small amount of CO2 in the atmosphere and its weak infrared absorption cross section (also in view of the various proves of NEGATIVE water feedback).
The present “stagnation” of global temperature (Fig. 5) is essentially due to the AMO/PDO: the solar de Vries cycle is presently at its maximum. Around this maximum it changes negligibly. The AMO/PDO is presently beyond its maximum, corresponding to the small decrease of global temperature. Its next minimum will be 2035. The temperature can expected to be then similar to the last AMO/PDO minimum of 1940. Due to the de Vries cycle, the global temperature will drop until 2100 to a value corresponding to the “little ice age” of 1870.
It accounts for the long temperature rise since 1870. One may note, that the stronger temperature increase from the 1970s to the 1990s, which is “officially” argued to prove warming by CO2, is essentially due to the AMO/PDO cycle.
 H.Luedecke, A. Hempelmann, C.O. Weiss; Clim. Past. 9 (2013) p 447
 F. Steinhilber, J. Beer; Journ. Geophys. Res.: Space Physics 118 (2013) p 1861