«
Since irradiance variations are apparently minimal, changes in the Earth's climate that seem to be associated with changes in the level of solar activity — the Maunder Minimum and the Little Ice age for example — would then seem to be due to terrestrial responses to more subtle changes in the Sun's spectrum of radiative output.
Not exact matches
We only have direct observations of total solar
irradiance (TSI)
since the beginning of the satellite era and substantial evidence for
variations in the level of solar activity (from cosmogenic isotopes or sunspot records) in the past.
Because of the
variations of sunspots and faculae on the sun's surface, the total solar
irradiance (TSI), also called the solar constant, varies on a roughly 11 - year cycle by about 0.07 %, which has been measured by orbiting satellites
since 1978 [Lean, 1987, 1991; Wilson et al., 1981].
The IPCC 2001 report states «Several recent reconstructions estimate that
variations in solar
irradiance give rise to a forcing at the Earth's surface of about 0.6 to 0.7 Wm - 2
since the Maunder Minimum and about half this over the 20th century... All reconstructions indicate that the direct effect of
variations in solar forcing over the 20th century was about 20 to 25 % of the change in forcing due to increases in the well - mixed greenhouse gases.»
Stable detectors placed aboard satellites above the Earth's atmosphere have been precisely monitoring the Sun's total
irradiance of the Earth
since 1978, providing conclusive evidence for small
variations in the solar constant.