An introductory lecture for proving that the global challenges of the XXI century spur chemistry to extend its scope

The global challenges of the twenty-first century compel contemporary scientific research to address Complex Systems, including all living organisms, natural ecosystems, urban environments, human societies, the global economy, the climate, and Earth's geology. At first glance, these systems appear very different from one another and are traditionally studied by well-distinct disciplines. However, interdisciplinary investigations of these systems, initiated as early as the eighteenth century and becoming systematic since the 1980s in several research groups worldwide, have revealed that they share common features. Chemical research also contributes to the study of such systems, playing a central role in describing biological and physicochemical systems. It is therefore important to understand the behavior of Complex Systems, the limitations of scientific research in studying them, and promising methodologies for deepening their comprehension. This lecture illustrates how the global challenges of the twenty-first century, together with the methodologies proposed to address them, are fostering a third revolutionary cultural event in humanity's journey to uncover the secrets of nature-an event that also involves chemistry itself. Chemistry is essential both for understanding and for contributing to this third revolutionary cultural event. A promising synergy between chemistry and the science of Complex Systems is claimed.