New Lovejoy paper says the ‘pause’ is ‘not so unusual’ & ‘no more than natural variability’
Shaun Lovejoy has published a new paper which cites his prior claim of 99.9% confidence that one of the two temperature graphs below is your fault, and the other due to natural variability.
Paul Homewood puts the claim to the test below.
Both graphs are half-century plots of HADCRUT4 global temperatures. Both use exactly the same time and temperature scales. Can you tell with 99.9% confidence which one is 1895-1945 (Nature’s fault), and which is 1963-2013 (Your fault)?
FYI according to Lovejoy’s claims, the top graph (1963-2013) is man-made, the bottom graph is due to natural variability.
In Lovejoy’s new paper, he acknowledges a ‘pause’ in global warming since 1998, says it’s “not so unusual” and concludes “the pause is no more than natural variability.” Indeed, the pause is due to natural variability that has not been accounted for by climate models, and thus invalidates attribution claims that the past 50 years of temperature variations are necessarily due to man-made CO2. Furthermore, prior work by NOAA and others has found ‘pauses’ of 15 or more years are indeed unusual and would suggest the climate models are overly sensitive to CO2. According to RSS satellite data, the ‘pause’ has lasted almost 18 years.
An approach complementary to General Circulation Models (GCM’s), using the anthropogenic CO2 radiative forcing as a linear surrogate for all anthropogenic forcings [Lovejoy, 2014], was recently developed for quantifying human impacts. Using pre-industrial multiproxy series and scaling arguments, the probabilities of natural fluctuations at time lags up to 125 years were determined.
The hypothesis that the industrial epoch warming was a giant natural fluctuation was rejected with 99.9% confidence. In this paper, this method is extended to the determination of event return times. Over the period 1880-2013, the largest 32 year event is expected to be 0.47 K, effectively explaining the postwar cooling (amplitude 0.42 – 0.47 K). Similarly, the “pause” since 1998 (0.28 – 0.37 K) has a return period of 20-50 years (not so unusual). It is nearly cancelled by the pre-pause warming event (1992-1998, return period 30-40 years); the pause is no more than natural variability.