"It's not the sun". Another look at what would happen if there were a Maunder Minimum this century.

Today WUWT-ers are in a dilemma. They are being asked to look at a climate discussion about the role of the sun in climate change. (The WUWT article is archived here.) Marcel Crok has posed a question for discussion at Climate Dialogue, namely:

What will happen during a new Maunder Minimum?

This question has been discussed at HotWhopper in the past, for example, here and here. And here is a link to a scientific paper on the subject, and one to a realclimate.org article. Even a grand solar minimum would only have a small temporary impact on global temperatures compared to the impact of rising greenhouse gases.

If you want to read the discussion by scientists, go to Climate Dialogue. The scientists who have presented their various scientific findings are:

• Mike Lockwood from the University of Reading
• Nicola Scafetta from Duke University
• Jan-Erik Solheim from the University of Oslo
• Ilya Usoskin from the University of Oulu
• José Vaquero from Universidad Carlos III de Madrid

The only public comment that appears so far is by Jos Hagelaars.

The problem WUWT-ers face is that in effect they have only two options:

• Mainstream science - that the sun has only a minor effect on climate at the moment, compared with the effect of rising greenhouse gases
• Scafetta-style science - by playing with numbers and patterns one can see all sorts of harmonics sufficient to muddy the science, while ignoring the impact of rising greenhouse gases.

Anthony Watts has already shafted Nicola Scafetta, so WUWT-ers aren't "allowed" to vote for his option. That mainly leaves the mainstream approach. The WUWT-ers don't appear to have coped too well with the dilemma, coming up with questions and various statements, but few answers. They are fumbling in the dark, without the benefit of sunlight.

The main purpose of this article is just to alert people to the discussion itself. Mike Lockwood's response is the longest and most detailed of all. The others are all worth reading too, to compare and contrast. What you'll notice is that different scientists pick different reconstructions to support their findings. Unfortunately there was a gap in the satellite readings, so scientists have had to try to align recent measurements with past measurements. Some scientists appear to have taken advantage of this gap to argue a less plausible scenario.

From the WUWT comments

Even if I had the time, I don't have the inclination to work through all the 52 WUWT comments. I'll just post a few of them.

Kenneth Wikerøy is waiting ever so patiently...

October 17, 2014 at 3:33 pm
It could be like this;
The sun is pouring out more or less a constant amount of energy per time.
We have a ball of water, where circulations are created because of the coriolis effect. These seacurrents are inhibited from flowing as they would have done without any landmasses.
This create complex oscillations.
It is the result of these oscillations we measure.
And that is all. When we started measuring, we jumped into a curve, seeing it go up and down. When it went a bit up, some people got panicked. Instead of just waiting a few years, and it would go down again.

n.n wrongly argues that "it's the sun", even though the Earth is warming while the sun sent less energy our way; and that "climate patterns" are too complicated for the brain of mere men and women to comprehend

October 17, 2014 at 6:30 pm
Exactly. Climate patterns ranging from sudden changes to indefinite periods of stability can be explained solely by the sun’s energy input, without additional sources. This does not mean that the sun is the sole source in the system, but it does imply that we lack the ability to identify, let alone discern the effects of different sources and sinks. The present and foreseeable scientific domain simply does not contain the skill and knowledge to forecast or predict chaotic processes over large time and space offsets from a known frame of reference. The system is both incompletely or insufficiently characterized, and unwieldy. 

tom in Florida is very much mistaken when he writes about 1934. In another comment he points to a WUWT article about US temperature records, not even US temperatures as such, and certainly not global temperatures, to support his wild claim!

October 17, 2014 at 3:48 pm
1934 is considered one of the, if not the warmest year on record. Yet the 3 solar cycles preceding were very weak. ???????????

Data sources: NASA GISS and Met Office Hadley Centre

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Feulner, Georg, and Stefan Rahmstorf. "On the effect of a new grand minimum of solar activity on the future climate on Earth." Geophysical Research Letters 37, no. 5 (2010). doi:10.1029/2010GL042710