THE ROLE OF THE SOLAR FORCING IN THE 20TH CENTURY CLIMATE CHANGE

A long list of empirical results strongly suggests that solar variations play an important role in climate change. We begin by trying to understand why such variations are crucial if we are to understand 20th century climate change, and how it is related to the value of the climate sensitivity. The latter is, of course, necessary if we are to predict future climate change. We then review some of the aforementioned evidence, and in particular, the data which can be used to quantify the size of the solar climate link. We will end by building a more consistent picture for 20th century global warming, while mentioning a few words on the expected 21st century climate change.