Together with Jean-Louis Le Mouël and some Russian colleagues, we have shown that some specific features of the magnetic field were remarkably well correlated with some variations in the sun’s activity – which in itself was not surprising – but the fact that it also correlated with the mean global temperature of the lower atmosphere came to us as a real surprise. This is how I started to get interested in climatology at the decadal to centennial time scale, an area which is not my specialty, though I had already encountered climatologists at the million year time scale with the Indian volcanism. It is clear that oil, gas and coal resources will eventually be depleted someday and to be reasonably cautious about decreasing consumption is a necessity. It does not need to be related to a legal precautionary principle.