Contents

20 May 2016
Vol 352, Issue 6288

About The Cover

Cover image expansion

COVER Massive fog rolls into Dubai, United Arab Emirates. As host to more than half of the world's population, cities have footprints that reach well beyond their municipal boundaries. Efforts are now under way to make urban areas more sustainable and efficient. The challenges and opportunities of our urban planet are highlighted in a special section beginning on page 904 and online at http://scim.ag/1Tb0WdZ.
Photo: ©Sebastian Opitz/Novarc Images