Final answer:
The atmospheric gas that recently surpassed 400 parts per million is carbon dioxide, primarily due to deforestation and the burning of fossil fuels. The correct answer is option: c) Carbon dioxide.
Step-by-step explanation:
- The current level of atmospheric carbon dioxide recently surpassed 400 parts per million. This milestone is significant as it represents a stark increase from the pre-industrial level of approximately 280 parts per million.
- The primary causes for this unprecedented rise are activities such as deforestation and the burning of fossil fuels like coal, oil, and natural gas.
- These practices have led to an increase in greenhouse gas concentrations, contributing to global warming and climate change.
- This alteration of our atmosphere raises concerns about its long-term impact on global temperatures, weather patterns, and the sustainability of various ecosystems.