The percentage increase in carbon dioxide concentration in the atmosphere from pre-industrial times is approximately

A55%

B50% ✓ Correct

C74%

D62%

Correct answer: (B) 50%

Explanation

Atmospheric carbon dioxide has risen by roughly 50 percent since pre-industrial times.

Levels have climbed from about 280 parts per million to over 420 parts per million.

The 55 percent figure overstates the observed rise.

The 74 percent value is far above the actual increase.

The 62 percent value likewise exceeds the measured change.

This rise is the main driver of the enhanced greenhouse effect.

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