New analysis suggests that the Moon might be an unappreciated factor in climate change and, according to researchers from the Universities of East Anglia and Reading, its influence “cannot be discounted as an important driver of multidecadal variability of global temperature.”
It’s a suggestion that is bound to prompt debate and a possible reassessment of the relative influence of human factors on climate change in the past and the future when the lunar effect is included.
It arises from the so-called lunar nodal cycle of 18.6 years caused by variations in the angle of the Moon’s orbital plane. During this period the Moon’s orbit “wobbles” between plus or minus 5 degrees relative to the Earth’s equator. When the lunar plane tilts away from the equatorial plane, the tides on Earth are reduced. When the Moon’s orbit is aligned with the Earth’s equator, the tides are exaggerated.
It is suggested that the lunar connection to climate is through the modulation of ocean tides the dissipation of which are a major influence in mixing in the world’s oceans. Some studies have been carried out suggesting a lunar link with the circulation of the Pacific Ocean. Now the researchers detect this cyclic signal in global and regional surface air temperature having amplitudes of 0.1 degree C and also in ocean heat uptake and ocean heat content.
The possible lunar signal in global surface air temperature and heat uptake are coincident with the so-called hiatus – the slowdown in global warming in the first decade of the 21st century.
Extrapolating this influence into the future the researchers say,
Our results suggest that the contribution of the lunar nodal cycle to global temperature should be negative in the mid-2020s before becoming positive again in the early-2030s.”
The signal is also present and possibly influencing warmer than average Arctic surface temperatures at the same time as the global warming hiatus. Enhanced energy input in the Arctic is found during the period 2007-2011. The all-time low in Arctic ice extend was in 2012 and has not yet been surpassed.
The researchers say that the lunar effect should be implemented in future climate models “in order that they better represent the effect of this repeatable and predictable source of climate variability on the impacts of climate change.”