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.
Figure 1. Hadley global temperature anomalies (black) with series adjusted by subtracting the scaled AMO (red).
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.Filed under: Sensitivity & feedbacks
