Digital twins are powerful tools for protecting our planet and improving how cities grow. Scientists and planners build virtual copies of forests, oceans, and urban areas to study how climate change, pollution, or new policies will affect them. For example, a city twin can show how adding green spaces or planting trees can reduce heat and improve air quality. Governments can also use city twins to plan roads, public transport, and buildings in ways that reduce emissions and make cities more sustainable. This helps both the environment and the people living in it.