Buchenwald survivors Alexander Bytschok, left, from Ukraine and Andrej Moiseenko from Belarus walk through the former Nazi concentration camp during celebrations marking the 70th anniversary of the liberation of camp Buchenwald near Weimar, Germany, Saturday. Markus Schreiber/AP
The encroaching desert surrounds homes in the golf resort city of Rancho Mirage, southern California. A fourth year of drought has prompted state governor Jerry Brown to order a 25% cut in domestic water consumption
Photograph: Damon Winter/New York Times/Redux/Eyevine
Impoverished Indians walk next to burning rubbish at Dharavi, one of the worlds largest slums, in Mumbai.
Air pollution kills more than 627,000 people in the country, according to the World Health Organisation. It puts 13 Indian cities in the worlds 20 most polluted
Photograph: Rafiq Maqbool/AP
A police special unit patrols a shantytown at Alemao in Rio de Janeiro, Brazil. Fresh violence in the citys slums has led to growing doubts over the effectiveness of Brazils seven-year-old strategy of pacifying districts in thrall to gangs and drug traffickers
Photograph: Yasuyoshi Chiba/AFP/Getty