David Evans discovered a form of notch filter operating between changes in sunlight and temperatures on Earth. This means there must be a delay — probably around 11 years. This not only fitted with the length of the solar dynamo cycle, but also with previous independent work suggesting a lag of ten years or a correlation with the solar activity of the previous cycle. The synopsis then is that solar irradiance (TSI) is a leading indicator of some other effect coming from the Sun after a delay of 11 years or so.
The discovery of this delay is a major clue about the direction of our future climate. The flickers in sunlight run a whole sunspot cycle ahead of some other force from the sun. Knowing that solar irradiance dropped suddenly from 2003 onwards tells us the rough timing of the fall in temperature that’s coming (just add a solar cycle length). What it doesn’t tell us is the amplitude — the size of the fall. That’s where the model may (or may not) tell us what we want to know. That test is coming, and very soon. This is an unusual time in the last 100 years where the forecasts from the CO2 driven models and the solar model diverge sharply. Oh the timing!
Science is about testable hypotheses. Over the next decade, the changes in temperature will reveal which theory is more correct, the carbon dioxide model or the notch-delay solar model.
Here’s the criterion: A fall of at least 0.1°C (on a 1-year smoothed basis) in global average surface air temperature over the next decade.
If the criterion does not occur: Then the notch-delay solar model is falsified and it should be thrown away.
If the criterion does occur: Then carbon dioxide driven models are falsified, and they should be thrown away. (Note that the carbon dioxide theory predicts only warming over longer periods such as a decade, and we’ve already had a pause in warming for 15+ years.)