Signals from the planets, via the Sun to the Earth

Abstract

The best method for identification of planetary forcing of the Earth’s climate is to investigate pe-riodic variations in climate time series. Some natural frequencies in the Earth climate system seem to besynchronized to planetary cycles, and amplified to a level of detection. The response by the Earth dependson location, and in global averaged series, some planetary signals may be below detection. Comparing sealevel rise with sunspot variations, we find phase variations, and even a phase reversal. A periodogram of theglobal temperature shows that the Earth amplifies other periods than observed in sunspots. A particular caseis that the Earth amplifies the 22 yr Hale period, and not the 11 yr Schwabe period. This may be explained byalternating peak or plateau appearance of cosmic ray counts. Among longer periods, the Earth amplifies the60 yr planetary period and keeps the phase during centennials. The recent global warming may be interpretedas a rising branch of a millennium cycle, identified in ice cores and sediments and also recorded in history. This cycle peaks in the second half of this century, and then a 500 yr cooling trend will start. An expected solargrand minimum due to a 200 yr cycle will introduce additional cooling in the first part of this century.