Roger Andrews: Global Warming Projections Using Solar Cycles

Guest post by Roger Andrews

Figure 8 shows the net solar and anthropogenic contributions to SAT

In a previous post (https://tallbloke.wordpress.com/2011/02/21/tallbloke-and-tim-channon-a-cycles-analysis-approach-to-predicting-solar-activity/) Tim Channon replicated the Lean TSI reconstruction very closely using a solar cycle-based analysis. Tim’s results are shown below:

In previous attempts to estimate how much global warming was solar and how much anthropogenic I used TSI, i.e. the sum of the amplitudes of all the solar cycles, to define solar forcing, with the implicit assumption being that all the solar cycles impact temperature in direct proportion to their amplitude. But now I’m going to assume that for reasons as yet unexplained some cycles have a larger proportionate impact than others.

So here I will attempt to match the global sea surface (SST) and surface air temperature (SAT) records using a phenomenological model that applies different forcings to each solar cycle. The cycles I used were Tim’s 426.5, 238.9, 112.5, 78.9 and 57.2 year cycles. The shorter 11-year cycles were ignored.

Figure 1 shows the results for ICOADS SST. I can fit SST very closely (R = 0.97 for annual SST data and 0.99 for smoothed) using solar cycles alone.

Figure 1

Figure 2 shows the individual solar cycle contributions. The 238.9 and 112.5 year cycles generate peak-trough temperature changes of 0.6C, the 78.9 year cycle a change of 0.4C and the 57.2 year cycle a change of 0.3C. The 426.5 year cycle has no detectable impact (it hardly varies over this time interval anyway).

Figure 2

Now I’m going to see if I can match the GISSmet surface air temperature series using solar cycles alone. The answer is no, I can’t. I have to include an anthropogenic component. But once I include it I get another good match (R= 0.91 for annual SAT means and 0.98 for smoothed), as shown in Figure 3:

Figure 3

Figure 4 shows the temperature impacts of all SAT forcings. The 238.9 and 78.9 year solar cycles now have the largest impacts and again there is no detectable contribution from the 426.5 year cycle. The anthropogenic forcings are from the GISS tabulation (http://data.giss.nasa.gov/modelforce/RadF.txt), and the factor applied to them equates to a climate sensitivity of 0.8C.

Figure 4

Figure 5 compares anthropogenic warming with the sum of the solar cycle warming. According to these results solar has caused most of the warming since 1880 and it has also contributed about as much warming over the second half of the 20^th century as we humans, despite what the IPCC claims:

Figure 5

According to the above model results man-made greenhouse gases warm only the air; the ocean is warmed entirely by the sun. There is no significant anthropogenic warming of the ocean from back radiation or anything else.

Armed with these results we can now project what sea surface and surface air temperatures are going to do for the remainder of the 21^st century. To do this for SST we need only extrapolate the solar cycles through 2100 and apply the factors used to obtain the best-fit match to observations. Figure 6 shows the results:

Figure 6

To project surface air temperatures we need an estimate of future anthropogenic as well as solar cycle forcings, and I got these from IPCC SRES A1B, a middle-of-the-road growth scenario that projects a gradual rise to 717ppm atmospheric CO2 by 2100. Applying the best-fit factors to the anthropogenic and solar forcings then gave the results shown in Figure 7:

Figure 7

Figure 8 shows the net solar and anthropogenic contributions to SAT:

Figure 8

According to these results there won’t be any significant global warming between now and 2100 – provided my analysis is realistic. Is it? Well, it’s admittedly speculative. But then, so are the climate models the IPCC uses to make its official global warming predictions. And my models fit observations a lot better too.