What significant environmental initiative was taken in California in the early 2000s?

The establishment of stricter vehicle emissions standards in California in the early 2000s was a crucial initiative aimed at reducing air pollution and addressing climate change. California has often been a leader in setting ambitious environmental policies, particularly in terms of automobile emissions. The state's regulations required car manufacturers to produce vehicles that emit fewer greenhouse gases, reflecting growing concerns about the impact of pollution on public health and the environment.

This initiative was part of a broader movement towards sustainability and environmental stewardship in California. The state recognized the significant role that transportation plays in air quality and climate issues, prompting the implementation of these standards as a way to encourage the production and use of cleaner vehicles.

In contrast, while the banning of plastic bags was an important environmental policy, it gained more widespread attention in later years and was not as prominent in the early 2000s. Opening national parks is more of a conservation effort and does not directly relate to vehicle emissions. Additionally, the promotion of fossil fuel extraction contradicts the goals of reducing emissions and environmental protection. Thus, the focus on vehicle emissions standards clearly marked California's proactive approach to tackling environmental issues during that period.