Bolivia was the bad boy of Cancun. It alone refused to adopt the text. Delegation head Pablo Solon told the conference that current pledges to cut emissions "would mean more than 4 ℃" of warming. It would be "ecocide", he said. It's not so simple. Stabilising temperatures at 2 ℃ of global warming - generally agreed to be the threshold for dangerous climate change - will require emissions to be brought down to very low levels eventually. That can happen in different ways. One widely used trajectory says that global annual CO_2 emissions in 2020 must be kept below 44 billion tonnes. Existing pledges overshoot that by 5 to 9 billion tonnes - the so-called "gigatonne gap".
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