Cities play a fundamental role in the search for solutions and policies to mitigate the problems driving global climate change. Today, urban areas account for more than 70% of carbon dioxide (CO₂) emissions—one of the main causes of the greenhouse effect and its consequences for the environment and human life.
This percentage is striking, considering that municipalities occupy a mere 0.4% to 0.9% of the Earth's surface, as pointed out by the study "Effects of population or density change on urban carbon dioxide emissions," published in Nature Communications—a journal specializing in natural sciences.
