Climatologists observed in 1964 that a slow warming of the surface of the North Atlantic in the
1910s and 1920s could well have been driven by a surge of warm water up the Gulf Stream.
This Atlantic warming accompanied a global warming that by the 1940s had produced the
highest global temperatures to that point in the records. It was so warm that statistical
techniques used in the 1990s to detect the “fingerprint” of greenhouse warming in climate
records also show the 1940s having greenhouse warming. However, no one believes enough
greenhouse gases had reached the atmosphere by then to cause much of a human-induced
warming. That inconsistency has led greenhouse contrarians to claim that any recent
warming could be natural rather than anthropogenic.
Consider each of the choices separately and select all that apply.
2. Which of the following statements about the global warming observed in the 1940s is
implied by the passage?
A. It was part of a climatic change that can be traced to the 1910s and 1920s.
B. Its cause was not apparent to climatologists until the 1990s.
C. It is doubtful that it was caused primarily by greenhouse gases produced by humans.
为什么C也是对的?原文说 ”no one believes enough..." 代表根本就不是doubtful,而是impossible才对呀,根本就没有争议