Testing for galactic cosmic ray warming hypothesis using the notion of block‐exogeneity

Abstract

AbstractIn this article, we consider the notion of block‐exogeneity and establish a characterization of it. We use this characterization to propose a procedure to test for block‐exogeneity in a trivariate system. The proposed procedure has been applied to test the so‐called galactic cosmic ray warming hypothesis. The galactic cosmic ray warming hypothesis suggests the existence of an indirect solar influence on Earth's climate. Our results seem to imply that this hypothesis does not hold. In particular, we find that the global temperature is block‐exogenous with respect to both sunspot numbers (a measure of the solar activity) and galactic cosmic rays. This implies that the supposed indirect causal link from solar activity to temperature (through cosmic rays), postulated by the galactic cosmic ray warming hypothesis, does not appear to exist.