Day 4 | Pre-Conference "Water, Megacities and Global Change"Paris, New York, Beijing, Mumbai, Tokyo, Buenos Aires, Mexico, Lagos… all Megacities – urban centers which accommodate more than 10 million inhabitants - are facing “mega”-challenges related to providing water services for their inhabitants, while managing their environment. Climate change effects of intensifying magnitude and global challenges such as sea level rise, increasing temperatures or urbanization, threaten these cities. Now, there is a need for action to achieve resilient cities. The Pre-Conference "Water, Megacities and Global Change" aims to put science at the service of megacities to help them address with the impact of climate change on their water management. From 7 to 11 December, 30 scientific papers will be presented and discussed by researchers, operators, civil society representatives, policy makers and students to understand and update the challenges of water management in megacities, and to design new, fairer and more effective models of water governance in cities resilient to the effects of climate change. The Pre-Conference "Water, Megacities and Global Change", co-organized by the Division of Water Sciences of UNESCO, SIAAP, ARCEAU-IdF, the Greater Paris Metropolis, with the support of Eau de Paris and Agence de l’eau Seine-Normandie, will pave the way towards the Second International Conference "Water, Megacities and Global Change" to be held at UNESCO Headquarters in December 2021 in Paris, France.