Modulation of cosmic ray precipitation related to climate

High energy cosmic rays may influence the formation of clouds and thus impa ct weather and climate. Due to systematic solar wind changes, the intensity of cosmic rays incident on the magnetopause has decreased markedly during this century. The pattern of cosmic ray precipitation through the magnetosp here to the upper troposphere has also changed. Early in the century, the p art of the troposphere open to cosmic rays of all energies was typically co nfined to a relatively small high-latitude region. As the century progresse d the size of this region increased by over 25% and there was a 6.5 degrees equatorward shift in the yearly averaged latitudinal position of the subau roral region in which cloud cover has been shown to be cosmic ray flux depe ndent. We suggest these changes in cosmic ray intensity and latitude distri bution may have influenced climate change during the last 100 years.