This year's lecture was devoted to variations in processes that influence climate and whose causes are linked to phenomena outside the earth. Particular attention was paid to solar variability, from recent decades to several millennia. After reviewing what is known with relative accuracy, I then addressed some recent studies and controversies concerning records of solar activity over more than ten thousand years and the hypothesis of direct climate forcing by cosmic rays modulated by the sun. I then examined current theories based on variations in the parameters of the Earth's orbit and their influence on insolation as a function of latitude and season. Developments were also discussed on the subject of the moon's climatic influence in the short and long term. I concluded this lecture by reviewing some recent debates on the influence of orbital inclination on extraterrestrial dust fluxes, and on the hypothesis of the long-term climatic impact of our galaxy's rotation.
Lecture