As this year's round of global climate talks begin in Durban, South Africa, negotiators once again try to tackle an elusive goal: Trimming nations' greenhouse gas emissions enough to meet the target of limiting global warming to less than 2 degrees Celsius (3.6 degrees Fahrenheit) before the end of the century.
This target is expected to reduce the potentially devastating effects of climate change, but, so far, it appears a long way off.
Last year, negotiators in Cancún, Mexico, agreed to the goal of limiting warming of the Earth's average surface temperature to 3.6 degrees F above pre-Industrial Revolution levels. Their agreement notes, however, that a ceiling of 2.7 degrees F (1.5 degrees C) might be warranted.
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A world 2 degrees warmer is not an ideal scenario. Even if nations are successful, the planet can still expect increasing heat spells, drought, flood damage and certain other severe weather events, along with elevated rates of extinctions and shifts in species' ranges, including those of disease-spreading insects, and many other potentially problematic changes, according to the Intergovernmental Panel on Climate Change 2007 Synthesis Report. Their severity grows along with increasing projected temperature rise, according to the report. [How 2 Degrees Will Change Earth]
Steps in the right direction
Some nations, mostly wealthy ones, have made voluntary commitments to reduce their emissions. The United States, for example, has agreed to take its emissions 17 percent below 2005 levels by 2020.
Unfortunately, added together, all of the nations' proposed cuts — if successful — would lead to about 5.8 degrees F (3.2 degrees C) warming by the year 2100, a significant distance from the target of 3.6 degree F, according to calculations by the independent science-based project Climate Action Tracker.
These voluntary commitments to reduce emissions are a "very, very positive sign," said Niklas Höhne, director of energy and climate policy for the independent research and consulting company Ecofys, one of the organizations behind Climate Action Tracker. "That is the real problem, so the ambition level is not sufficient on these voluntary actions."
Replacing Kyoto?
Industrialized nations, not including the U.S., have made legally binding commitments to reduce their emissions as part of the Kyoto Protocol in 1997. The commitment period for when nations can sign up for the Kyoto Protocol expires next year. Negotiators have the option of extending it, coming up with a replacement, or allowing this legal framework to fade away. Some developped nations have opposed extending the treaty, over the objections of developing nations. Most recently Canada, which is not meeting its original pledge, appears poised to pull out.
Some sort of continuation is needed, said Joe Romm, editor of the blog Climate Progress and a senior fellow at the progressive think tank Center for American Progress.
"I think voluntary reductions are valuable, but ultimately, they will not replace serious, mandatory commitments," Romm said.
A new treaty or any substantial action is unlikely to come from Durban, said Romm, who is not optimistic about the future.
"We are going to get 2 degrees C (3.6 degrees F) warming," he said. "I think the big question is whether we are going to get ultimately 5 or 6 degrees C (9 to 10.8 degrees F), which would be an unmitigated catastrophe."
Negotiators need to act on the future of the Kyoto Protocol, Höhne said. "This is really the last chance to keep the Kyoto Protocol alive; if there is no decision on it, then it doesn't have real meaning anymore."
Baby steps
At Durban, negotiators are also tackling more modest issues, such as figuring out how to structure, and finance, a Global Climate Fund, which would funnel $100 billion a year to developing nations to help them cope with climate change. They will also work on reducing forest destruction and encouraging the development and sharing of clean technology.
Höhne sees reasons for hope, such as rapid progress regarding alternative energy sources, such as wind, the sun and biomass. [Top 10 Alternative Energy Bets]
"I am not that optimistic, but I have not given up the hope," he said.
You can follow LiveScience senior writer Wynne Parry on Twitter @Wynne_Parry. Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on Facebook.
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