Friday, November 21, 2003, 16:00
OSGA/E6
Prof. J. Kirkby, CERN
Abstract:
The Earth's climate is far from stable and has undergone changes over
periods from decades to billions of years. The current view is that
variations of greenhouse gases and of Earth's orbit around the Sun are
the primary drivers of climate change on all these time scales.
However, for more than two centuries, observers have persistently
concluded that solar variability is also an important contributor -
although the physical mechanism has remained a mystery. Recent satellite
observations have provided an important new clue, namely that cloud
cover may be affected by galactic cosmic rays (whose intensity varies
with the solar wind). Plausible microphysical mechanisms have been
suggested to explain this association, although none is experimentally
established. Furthermore, within the last year or so, diverse
paleoclimatic observations have revealed a striking association of
cosmic ray intensity and climate change extending back to the earliest
times on Earth. The evidence seems to be pointing to the remarkable
possibility that our climate may be celestially controlled. We will
explore this evidence and discuss the future experimental directions to
resolve the question.