The extension was adopted by nearly 200 countries after hard-fought sessions and despite objections from Russia. The package of decisions also included vague promises of financing to help poor countries cope with climate change.
Though expectations were low for the two-week conference in Doha, many developing countries rejected the deal as insufficient to put the world on track to fight the rising temperatures that are raising sea levels. Some Pacific island nations see this as a threat to their existence.
"This is not where we wanted to be at the end of the meeting, I assure you," said Nauru Foreign Minister Kieren Keke, who leads an alliance of small island states. "It certainly isn't where we need to be in order to prevent islands from going under and other unimaginable impacts."
The 1997 Kyoto Protocol, which controls the greenhouse gas emissions of rich countries, expires this year. It was extended through 2020 to fill the gap until a wider global treaty is expected to take effect.
However, the second phase only covers about 15 per cent of global emissions after Canada, Japan, New Zealand and Russia opted out.
The U.S. never joined Kyoto, partly because it didn't include China and other fast-growing developing countries.
Poor countries came into the talks in Doha demanding a timetable on how rich countries would scale up climate change aid for them to $100 billion annually by 2020 — a general pledge that was made three years ago.
But rich nations, including the United States, members of the European Union and Japan are still grappling with the effects of a financial crisis and were not interested in detailed talks on aid in Doha.
The agreement on financing made no reference to any mid-term financing targets, just a general pledge to "identify pathways for mobilizing the scaling up of climate finance."