What is a notable effect of excess carbon dioxide (CO2) in the atmosphere?

Excess carbon dioxide (CO2) in the atmosphere has a significant impact by contributing to the greenhouse effect. The greenhouse effect occurs when certain gases in Earth's atmosphere trap heat, preventing it from escaping back into space. CO2 is one of the primary greenhouse gases, and its increased concentration enhances this effect, leading to global warming and climate change.

This warming affects weather patterns, sea levels, and various ecosystems. As CO2 levels rise, the Earth becomes warmer than it would be otherwise, resulting in numerous environmental changes. This underpins the urgency of addressing CO2 emissions to mitigate climate change and its wide-ranging effects on the planet.

While other options may hint at environmental implications of CO2, they do not encapsulate the primary role that excess CO2 plays in altering the Earth's climate system through the greenhouse effect.