Environmental challenges and sustainability are critical issues in our rapidly changing world. From climate change to deforestation, water scarcity to air pollution, these problems impact ecosystems and human well-being globally. Understanding their causes, effects, and potential solutions is crucial for addressing these complex issues. This unit explores key environmental challenges, their human impacts, and sustainable approaches to mitigate them. It covers concepts like circular economy and ecosystem services, examines global case studies, and discusses policies, technologies, and individual actions that can contribute to a more sustainable future.