Update May 13 below
This post presents key findings from the recently published paper:
Anthropogenic CO2 warming challenged by 60-year cycle (here) by
Department of Physics, Faculty of Sciences & Techniques, François Rabelais University, Parc de Grandmont, 37200 Tours, France
In the synopsis below, Gervais puts his study in context, followed by his conclusions.
The Global Warming Debate Rages
The impact on climate of the CO2 emitted by burning of fossil fuels is a long-standing debate illustrated by 1637 papers found in the Web of Science by crossing the keywords
“anthropogenic” AND “greenhouse OR CO2” AND “warming”
This is to be compared to more than 1350 peer-reviewed papers which express reservations about dangerous anthropogenic CO2 warming and/or insist on the natural variability of climate.
Signatures of 60-year Climate Wave
Time series of sea-level rise are fitted by a sinusoid of period ~ 60 years, confirming the cycle reported for the global mean temperature of the earth. This cycle appears in phase with the Atlantic Multidecadal Oscillation (AMO). The last maximum of the sinusoid coincides with the temperature plateau observed since the end of the 20th century. A 60-year climate cycle is confirmed in sea-level rise and global sea ice area, as well as in measured temperature series.
Onset of the Declining Phase
The four following indicators sign for the onset of the declining phase of the 60-year cycle.
- The recent change of sign of global sea ice area anomaly which
reveals an excess in Fig. 3, a sensitive indicator of climate, is unexpected
from model projections (AR5, 2013).
- The AMO index indicates the onset of a declining phase.
- A negative temperature slope is measured from 2002 to 2015 independently by different satellites in the low troposphere by Remote Sensing System (RSS, 2015) and by UAH (Spencer et al., 2015) as shown in Fig. 4. The plot is voluntarily restricted to 13 years, viz. less than 1/4 of the 60 year-cycle, to evaluate the sign of the tangent to the sinusoid.
- A deceleration of the sea-level rise measured by satellite altimetry is also found since 2002 (Chen et al., 2014; Cazenave et al.,2014).
Rising Temperatures cause rising CO2
The correlation of yearly CO2 increase, therefore, appears not with MEI or SOI but with global mean temperature to which El Niño and La Niña contribute. This temperature/CO2 correlation may be tentatively explained, at least partly, by the solubility of CO2 into water which decreases with temperature, consistent with sea pH maps (Byrne et al., 2010). Warm temperature fluctuations favor CO2 release from the oceans which contain 60 times more CO2 than the atmosphere (AR5, 2013), whereas cooler fluctuations favor its oceanic Capture.
Summary: 60-year Wave Rules
Dangerous anthropogenic warming is questioned (i) upon recognition of the large amplitude of the natural 60–year cyclic component and (ii) upon revision downwards of the transient climate response consistent with latest tendencies shown in Fig. 1, here found to be at most 0.6 °C once the natural component has been removed, consistent with latest infrared studies (Harde, 2014). Anthropogenic warming well below the potentially dangerous range were reported in older and recent studies. On inspection of a risk of anthropogenic warming thus toned down, a change of paradigm which highlights a benefit for mankind related to the increase of plant feeding and crops yields by enhanced CO2 photosynthesis is suggested.
The whole paper is well worth the read, and is chock full of links to sources and references supporting his analysis.
Here is a recent Youtube video of Francois Gervais presenting his findings (with English translation)
Update May 13
In the comments below ren points to the declining NAO, with the implication that a cooling phase is underway in the North Atlantic SSTs. The cold blob in the North Atlantic was subject of a post here and elsewhere, and Paul Homewood posts today on the increasing cold water, not only surface but coming from below.
Dr. Gerard McCarthy is a lead researcher on the RAPID array project measuring the AMO heat transport and provides a good context on their observations and the implications for the climate cooling in coming decades.
Our results show that ocean circulation responds to the first mode of Atlantic atmospheric forcing, the North Atlantic Oscillation, through circulation changes between the subtropical and subpolar gyres – the intergyre region. This a major influence on the wind patterns and the heat transferred between the atmosphere and ocean.
The observations that we do have of the Atlantic overturning circulation over the past ten years show that it is declining. As a result, we expect the AMO is moving to a negative (colder surfer waters) phase. This is consistent with observations of temperature in the North Atlantic.