An ingeniously constructed record of sunspot activity shows that the current episode is the most intense for several thousand years. But that does not let us off the anthropogenic hook of global warming. Dark spots or 'blemishes' on the face of the Sun (Fig. 1) were recognized from the early seventeenth century, and have since been identified as places where strong magnetic fields emerge from the Sun's surface. Data on sunspot numbers provide the longest observational record of solar activity. But that record is too short to document changes in activity occurring on timescales longer than the recognized cycles of 11- and 88-year periods, or to support claims for a connection between solar activity and Earth's climate on centennial to millennial timescales.
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