So is the Sun’s cycle linked to global warming? The key line is this entire article is that “Milligan, like most scientists, enters many caveats and warns that specific weather predictions are very difficult to make and that this form of study is in its relative infancy”. We may have a tentative correlation, but what does a correlation tell us? It is well-known that the global temperature is inversely correlated to the number of pirates in the Sea (*) . But one does not cause the other, i.e, causality is missing. Causality differs from correlation in a key manner in that causality does not only say A is linked by B, by it predicts how much A will change if B changes. In this case we can model global temperature changes from the burning of fossil fuels and predict how much this temperature change will be. But when we try to model the link to solar changes it turns out to be very small, if it exists at all. Correlation without causality will disappear when faced with lots of data.
(*) In this case, the causality is the rise of the global population and technology. As our society is now larger and more advanced than the 19th century, we no longer do everything by sea and so the number of pirates has plummeted. As our society is now larger and more advanced than the 19th century, we burn more fossil fuels and hence global temperatures has risen. Hence the correlation occurs through a common causal mechanism.