Does a steep drop in solar activity imply an equally steep drop in temperatures?

David Archibald’s prediction for global average temperature 2014-2025

David Archibald’s post at Quadrant.org.au has stirred some interesting debate here at the talkshop. David predicts an imminent and steep drop in regional temperatures as a result of the slowdown in solar activity seen since the descent of solar cycle 23 in 2003. It’s not the first time he has made such predictions. As Nick Stokes pointed out in discussion, Archibald told the Australian senate committee in 2009 that temperature was about to go down at a scary 0.2C per annum. It didn’t happen. But David says it’s different this time, because a decade has passed since solar cycle 23 dropped towards a long minimum, followed by the weak cycle 24 we are currently in. The decadal lag is implied by David Evan’s new hypothesis which identifies a ‘notch filter’ which points to a cycle-long lag between changes in solar activity and the effect becoming visible in the terrestrial response. David goes on to predict that due to Penn and Livingstone’s prediction of a very low sunspot number in cycle 25, we are headed for drastic cooling.

There are several points on which I disagree with David’s analysis, and I’ll cover them below the break.

Contrary to David Evan’s hypothesis I think that the cause of a decadal lag between solar change and climate response is to be found in the oceans, not the Sun. Seawater has a high heat capacity, and it’s deep. This mass of global ocean damps the climate response to solar input. It also stores and releases energy on long timescales. This is why the latest explanations for the ‘pause’ in ‘global warming’ hypothesises that the ocean is eating excess energy. This is correct in my opinion, except it’s not excess energy from an alleged ‘enhanced greenhouse effect’ that it’s eating, it’s solar energy, which penetrates the ocean to a depth of 100m, whereas longwave radiation from the atmosphere can’t penetrate the ocean surface.

What the co2 driven global warming advocates don’t discuss is that if the ocean has started eating global warming since the trade winds changed during the negative phase of the ocean’s ~60 year multi-decadal cycles, they also emitted excess energy during their positive phase from 1975-2005. The implication is that the oceans are capable of storing energy on long timescales, and releasing it on long timescales too. And they store a lot of energy. The top two metres alone contain as much energy as the entire atmosphere above.

We know that the oceans keep the air temperature up over night as the release some of the energy the Sun poured into them during the day. We also know that there is a lag of a couple of months between the longest day of the year and the peak in surface air temperatures near coasts. This is thermal inertia and heat capacity at work. On longer timescales, we have recently confirmed that runs of El Nino events which release a lot of energy from the oceans are initiated on the falling side of the solar cycle, never on the upswing.

So we can go a stretch further and combine what we know. When solar activity falls, energy comes out of the ocean, not just over the period of the decline of a single 11 year solar cycle, but if the Sun stays low in activity terms, for many years. An integration of the sunspot number shows us that the ocean heat content rose all the way from 1934 to 2003. This is the real cause of ‘global warming’. A lot of excess energy is still retained in the upper ocean. We can expect the effect of a couple of low solar cycles to be softened by a proportion of that excess heat returning to space via the atmosphere warming it on the way.

In developing my understanding of the Earth’s systems, I developed a couple of very simple models to help me fathom the way the surface temperature stays fairly constant as the solar cycles wax and wane. Back in 2009, by analysing the data, I found that the global average sea surface temperature, the SST, stays fairly constant when the Sun is averaging around 40 sunspots per month. By calculating the running total departing from this figure in a simple integration I found that combined with the ~60 oceanic cycles (also solar influenced), I could reproduce the temperature history of the last 150 years quite accurately. By adding in a nominal forcing for co2 (or an allowance for the infamous ‘adjustments’ to the data), I was able to get a match to monthly data which has a Pearson R^2 value of 0.9.

By using our planetary technique to predict future solar activity I was then able to make a prediction based on the ocean response to falling solar activity, and here’s the result:

As you can see, by including the thermal inertia of the oceans, and accounting for the ongoing ~60 oceanic cycles, the drop in gllobal temperature is nothing like as severe or sudden as David Archibald predicts. But what about his regional and agricultural predictions?

History tells us that when solar activity drops to very low levels, we can get strong swings in temperatures in the temperature latitudes of the northern hemisphere due to ‘loopiness’ in the jetstream dragging cold arctic air in to our weather systems. This may adversely affect growing season lengths and crop damage due to hail and frosts, particularly in the middle of large continents away from coasts. My prediction is that we are headed for weather similar to the early 1970’s, and if the solar minimum brings more than a couple of low cycles, it’ll be woolly trousers like my Grandfather wore in his youth in 1905 that we need.

But this brings me to my other point of disagreement with David Archibald. Even if Livingstone and Penn are right about the sunspot number dropping as low as 7SSN during cycle 25, this doesn’t necessarily mean that the electromagnetic flus from the Sun will be as low as during the long minimum between cycles 23 and 24. The relationship between F10.7 flux and sunspot number might change.

However, it seems likely that the amounts of short UV wavelengths will be low, and that might spell trouble for agriculture for other reasons than low temperatures. UV kills bacteria and fungi, and a lack of UV allows bacteria and fungi to flourish. Crop disease may become more of an issue, and disease happens in very non-linear ways.

So although I disagree with David Archibald’s temperature analysis, we should nonetheless pay attention to his concerns over agriculture. Storage silos are needed, as we currently operate a ‘just in time’ food network worldwide. The ancient pharoahs of Egypt had the sense to have sufficient storage to maintain grain stocks able to ride out multi-year drought. As Ghandi said with his last words

Don’t waste the food