To evaluate the statements about carbon dioxide levels based on historical geologic periods, we can analyze each option:
A. Human activities contributed to the increase in carbon dioxide levels that occurred during the Jurassic geologic period.
- This statement is unlikely to be true. The Jurassic period occurred from about 201 to 145 million years ago, long before humans existed. Therefore, human activities could not have contributed to changes in carbon dioxide levels during that time.
B. During the Permian geologic period, the amount of carbon dioxide in the atmosphere increased due to natural processes.
- This statement is plausible. The Permian period (approximately 299 to 252 million years ago) did see fluctuations in carbon dioxide levels, often attributed to natural processes such as volcanic activity and the formation of coal deposits.
C. During the Carboniferous geologic period, carbon dioxide levels reached their highest point in geologic history.
- This statement is likely false. The Carboniferous period (about 359 to 299 million years ago) experienced a significant drop in carbon dioxide levels compared to earlier periods due to the extensive formation of coal forests. It's generally believed that the Carboniferous had lower CO2 levels as a result of these processes.
D. Carbon dioxide levels are higher today than they have been at any other time in geologic history.
- This statement is also likely true. Current atmospheric carbon dioxide levels have reached levels that are unprecedented in recent geological history, particularly since measurements began in the late 20th century.
Based on this analysis, the most likely true statement from the options provided is:
B. During the Permian geologic period, the amount of carbon dioxide in the atmosphere increased due to natural processes.