People walk past the ground paintings themed on environmental protection at Montgomery Street in San Francisco, the United States, Sept. 25, 2019. A total of 13 ground paintings themed on environmental protection were created on Wednesday in San Francisco to call for reduction of fossil fuel use and investment on green energy. (Photos: Xinhua)

People walk past the ground paintings themed on environmental protection at Montgomery Street in San Francisco, the United States, Sept. 25, 2019. A total of 13 ground paintings themed on environmental protection were created on Wednesday in San Francisco to call for reduction of fossil fuel use and investment on green energy.

A woman walks on the ground painting themed on environmental protection at Montgomery Street in San Francisco, the United States, Sept. 25, 2019. A total of 13 ground paintings themed on environmental protection were created on Wednesday in San Francisco to call for reduction of fossil fuel use and investment on green energy.

People look at the ground paintings themed on environmental protection at Montgomery Street in San Francisco, the United States, Sept. 25, 2019. A total of 13 ground paintings themed on environmental protection were created on Wednesday in San Francisco to call for reduction of fossil fuel use and investment on green energy.

People take part in an activity on the ground paintings themed on environmental protection at Montgomery Street in San Francisco, the United States, Sept. 25, 2019. A total of 13 ground paintings themed on environmental protection were created on Wednesday in San Francisco to call for reduction of fossil fuel use and investment on green energy.

People take part in an activity on the ground painting themed on environmental protection at Montgomery Street in San Francisco, the United States, Sept. 25, 2019. A total of 13 ground paintings themed on environmental protection were created on Wednesday in San Francisco to call for reduction of fossil fuel use and investment on green energy.