Last week, the newly published Gagn√© et al. (2017) paper received some attention because the authors pointed out that Arctic sea ice grew substantially between 1950 and 1975, consistent with the in-phase cooling trend during that period.
Gagn√© et al., 2017 “Updated observational datasets without climatological infilling show that there was an increase in sea ice concentration in the Eastern Arctic between 1950 and 1975, contrary to earlier climatology in-filled observational datasets that show weak inter-annual variations during that time period.”
The AARI [Arctic and Antarctic Research Institute] and Walsh & Chapman sea ice data sets used in the paper (see graph above) included exclusively observational evidence — “climatological infilling were not included … we only used observed data”. Both observational data sets indicated that Arctic sea ice concentration anomalies were as low or lower in the early 1950s than they have been during recent decades.
During the early 1950s, CO2 concentrations hovered between 310 and 315 ppm. Today, atmospheric CO2 has reached 400 ppm. And yet early 1950s sea ice extent was similar to or lower than today. This would imply that the Arctic sea ice recession observed in recent decades is well within the range of natural variability, or within the range of what has occurred without human interference or high rates of anthropogenic CO2 emissions.
In the recently published scientific literature, distinguishing between a presumably human-caused influence on climatic trends and natural or internal variability (or “noise”) has not only become more and more difficult, scientists are increasingly pointing out that an anthropogenic signal in climate trends “has yet to be detected above the level of natural climate variability.”
In addition to the more than 20 new scientific papers affirming a robust connection between solar forcing and climate already published in 2017, there are another new 20 scientific papers that indicate natural variability and/or natural oceanic/atmospheric oscillations (ENSO, NAO, PDO) dominate as modulators of precipitation, temperature/climate, and sea level/flooding.