by Craig Loehle
This is a short summary of my new paper Global Temperature Trends Adjusted for Unforced Variability.
The possible implications of internal or unforced variability in the Earth climate system is a frequent topic on Climate Etc. I hypothesized that the AMO might provide an index to unforced variability. I scaled it and subtracted it from the Hadley global data (Fig. 1). Subtracting the scaled AMO reduces the variance of the data and changes the shape.
I extracted total anthropogenic forcing from the IPCC AR5 appendices. A comparison of the adjusted Hadley data with forcing estimates (Fig. 2) shows a remarkable similarity of shape with a simple correlation of 0.92.Figure 2. Adjusted Hadley global temperature (black) vs. scaled (arbitrary scale) anthropogenic forcing (red).
Based on an approximately linear temperature trend since 1970, I obtained an estimate of 0.83 deg C/century for the warming rate over the 44 years. This would give 0.71 deg C more warming by 2100 as a simple extrapolation. This corresponds to TCR=1.2 and ECS=1.5.
Since the paper is open access and is short, I encourage you to read the full paper.
JC note: As with all guest posts, please keep your comments civil and relevant.