We're hoping these ads predict the wrong future -- the one where world leaders look back with a "coulda, shoulda, woulda" attitude at a Copenhagen climate summit which failed. There's still time to change the future. Our recipe for world leader regret-avoidance is simple: agree a fair, ambitious, and legally binding deal to save the climate.

Barack Obama (US)

Angela Merkel (Germany)

Nicolas Sarkozy (France)

Gordon Brown (UK)

Luiz Inacio Lula da Silva (Brazil)

Donald Tusk (Poland)

Jose Luis Rodriguez Zapatero

Stephen Harper (Canada)