While there have been countless attempts at correlating sunspot cycl

游客2024-01-11 27

问题          While there have been countless attempts at correlating sunspot cycles with
   such diverse phenomena as the economy, crop yields, and the weather, there has
   been little evidence to support these correlations. The past few decades have
Line seen a renewed interest in the sun-climate relationship with a comprehensive
(5)    analysis of many different historical records of solar observation. Late in the
   seventeenth century, a period known as the Maunder Minimum, there were
   virtually no sunspots observed, indicating a "quiet" period in the sun’s activity
   coinciding with the height of a time known as the Little Ice Age, a period of
   lower temperatures in Europe. Once this evidence had been synthesized, it has
(10)    become much clearer that there are indeed robust correlations between the
   Earth’s temperature and sunspots. Perhaps the most important development in
   the solar-climate link came when satellites were developed to measure, in rough
   terms, the Total Solar Irradiance (TSI), a factor shown to be directly related to
   these "activity" cycles. At the maxima of these cycles, there are more sunspots
(15)    (magnetic phenomena that attenuate local irradiance), but new instruments
   show that these dark sunspots are more than compensated for by bright areas on
   the sun called faculae; therefore, the overall irradiance increases in
   correspondence with higher numbers of sunspots.
         Unfortunately, identifying this evident increase in minimum values as a
(20)    trend provokes concern, as there have been only two minima ever measured in
   this way. We must be aware that the warming trend in the surface temperature
   goes far beyond the last two decades, and that an extension of the solar record
   is necessary to assess whether solar activity and irradiance is indeed increasing
   at the minima of the cycles and what the potential effect on the climate may be.
(25)    The solar record has been extended by the use of the historical sunspot records
   already mentioned and correlations have been drawn between solar irradiance
   and the temperature curve since 1610, suggesting a predominant solar influence
   in the pre-industrial period. But since 1860 only half the observed warming
   could be attributable to the irradiance increase, indicating that some other
(30)    influence is becoming more influential in controlling the temperature change:
   most likely industrial carbon-dioxide.
         Recent studies of global warming have necessitated a more comprehensive
   effort to quantify the natural climate variability so that the residual change may
   be attributed to the anthropogenic emissions of greenhouse gases. This attempt
(35)    at quantification of the many different forces effect on the climate has re-
   emphasized the complexity of the climate system and the simultaneous
   interaction of many influences. Solar irradiance may indeed account for some of
   the temperature increases recorded over the last several decades, but as the
   atmospheric CO2 rises, due to the exponential increase in emissions from
(40)    industrial sources, the influence of solar variability on the Earth’s climate will
   most likely decrease, and its relative contribution will be far surpassed by
   "greenhouse" gases. [br] Which of the following statements concerning the comparison between pre- industrial and post-industrial climate change, as described in the passage, is accurate?

选项 A、The pre-industrial period experienced a much greater degree of climate change, owing to solar activity.
B、The post-industrial period experienced a much greater degree of climate change, owing to greenhouse gases.
C、Both periods have experienced a degree of change, but their primary causes are different.
D、Both periods have experienced a degree of change, and their primary causes are identical.
E、Scientists have yet to prove that climate change is linked to either sunspots or greenhouse gases.

答案 C

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