The devastating storms of recent days have generated dozens of avalanches that have swept away entire villages. There have been 271 confirmed deaths in Nova Friburgo, 261 in Teresopolis, 55 in Petropolis, 19 Sumidouro and four in Sao Jose do Vale do Rio Preto – and many people are still unaccounted for. Heavy rains in five municipalities of Rio de Janeiro have added to the problems – here there are 610 dead, according to official figures, and 7,000 families homeless.

A mobilization of rescue forces has seen the Ministry of Defence dispatching 586 soldiers to help the victims, while the armed forces have moved 12 helicopters, 74 vehicles, two bulldozers, a field hospital, three ambulances, a generator and lighting tower into the region. In addition, the Ministry of Justice has sent 225 men to Rio de Janeiro, of whom 80 are military fire rescue specialists, 130 police and 15 military experts to assist in identifying bodies.

The intensification of storms caused a temporary suspension of the rescue work. Colonel Luiz Castro, commander of the Civil Defence, reported that a planned rescue of 80 people in Brejal, had to be postponed because of bad weather. Colonel Pedro Machado elaborated on the problems: ‘We are having problems with the weather. Helicopters are failing so far to make the long distance trips [needed] to provide care to people who are still isolated in rural areas.’

In the face of one of Brazil’s greatest tragedies, governor of Rio de Janeiro Sergio Cabral declared seven days of official mourning starting on Monday of next week. He also decreed a state of emergency for a period of 180 days and said the state will build 3,000 houses for the victims. President Dilma Rousseff has also decreed three days of official mourning.

The world is witnessing increased frequency and power of extreme weather events. As in Brazil, so in Australia, the Philippines and Sri Lanka. And the situation will not improve until measures to mitigate climate change and to end greenhouse gas emissions reach the required level.

World leaders need to work seriously to meet the needs of millions of environmental refugees – whose number will continue to grow. It is clear that much remains to be done. The Brazilian newspaper O Estado de Sao Paulo recently published a document that the Brazilian government had sent to the UN three months ago, recognizing that the country was ‘not prepared’ to cope with natural calamities. The report is signed by Ivone Maria Valente, member of the National Secretariat of Civil Defence (Sedec).

The type of climate catastrophe we are witnessing must force leaders to rethink where and how to build cities, and their future plans for dealing with such events.