The world is close to reaching tipping points that will make it irreversibly hotter, making this decade critical in efforts to contain global warming, scientists warned at the “Planet Under Pressure” conference in London, reports Nina Chestney at Reuters. Scientific estimates differ but the world’s temperature looks set to rise by six degrees Celsius by 2100 if greenhouse gas emissions are allowed to rise uncontrollably. As emissions grow, scientists say the world is close to reaching thresholds beyond which the effects on the global climate will be irreversible, such as the melting of polar ice sheets and loss of rainforests. “This is the critical decade. If we don’t get the curves turned around this decade we will cross those lines,” said Will Steffen, executive director of the Australian National University’s climate change institute, speaking at a conference in London. Besides melting ice sheets, which expose much more darker, heat absorbing surfaces, tipping points include melting of the Siberian permafrost, which could then release huge amount of the short-lived but very potent greenhouse gas, methane. Humanity has answers but voters must elect green leaders who will take action soon.