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Abstract

Two simulations have been carried out With a global coupled ocean—atmosphere cir-
culation model to study the potential impact of solar variability on climate. The Hoyt
and Schatten estimate of solar variability from 1700 to 1992 has been used to force
the model. Results indicate that the near—surface temperature simulated by the model
is dominated by the long periodic solar fluctuations (Gleissberg cycle), with global
mean temperatures varying by about 0.5 K. Further results indicate that solar vari—
ability induces a similar pattern of surface temperature change as the increase of
greenhouse gases, i. e. an increase of the land—sea contrast. However, the solar—
induced warming pattern over the ocean during Northern Hemispheric summer is
more centered over the Northern Hemisphere subtropics, compared to a more uni-
form warming associated with the increase in greenhouse gases. Finally, the magni—
tude of the estimated solar warming during the 20th century is not sufficient to
explain the observed warming. The recent observed 30-year trends are inconsistent
with the solar forcing simulation at an estimated 90% significance level. Also, the
observed trend pattern agrees better with the greenhouse warming pattern.