As negotiations wrap up in Copenhagen, there’s been concern over a leaked U.N. document , published by the U.K.’s Guardian newspaper  last night, that shows that nations' maximum offers to reduce emissions fall between roughly 2 and 4 billion tons of carbon short of what’s needed to remain below the dangerous 2°C boundary by the end of the century. Those offers were put on the table in advance of the summit.
But now a U.K.-based scientist says that nations could potentially make up nearly the entire shortfall by accelerating what is already an aggressive effort to reduce emissions from deforestation and degradation (REDD), an expected outcome  of the talks.
The U.N. document, which some say has been overhyped , says that emissions would have to peak at 44 gigatons (Gt) a year between 2015 and 2020—but that we are currently scheduled to overshoot that target. If nations offer deeper cuts than they had offered before, which is likely, the overshoot would be less. The document states:
Unless the remaining gap of around 1.9 to 4.2 Gt is closed and Parties commit themselves to strong action prior and after 2020, global emissions will remain on an unsustainable pathway that could lead to concentrations equal or above 550 ppm with the related temperature raise around 3 °C.
The leaked document is based on figures put out by nations prior to Copenhagen , so it is unlikely to reflect new commitments, like the European Union's offer to cut its emissions by 20% based on 1990 levels in the run-up, but here in Copenhagen it has said it will now cut emissions by 30% if an international agreement can be reached.
The 2 to 4 billion ton —or gigatons—overshoot is based on the latest emissions scenarios from the International Energy Agency and projections from the U.N.’s Intergovernmental Panel on Climate Change (IPCC). They found that to stay on a 450 ppm path, which would keep an average increase in world temperatures below 2°C, developed countries would need to cut emissions by 25% to 40% of 1990 levels. Developing countries would need to cut their emissions significantly below "business as usual" levels.
So how could deforestation help?
The draft text of an agreement being negotiated in Copenhagen this week states the aim of reducing deforestation in developing countries by around 25% over the next 5 years. But Bernardo Strassburg, a researcher at the University of East Anglia and the Institute for Global and Applied Environmental Analysis in Brazil, says that “existing studies show that REDD [Reducing Emissions from Deforestation and Forest Degradation] can do much better.” Here's one  example.
The U.N document, which predicts the overshoot, also takes into account only 1.6 Gt of mitigation of emissions from REDD. But “estimates in several published studies suggest that REDD could in fact deliver a 50% or even a 90% reduction [in deforestation over the next 10 years],” he says, if it was properly financed, implemented and monitored. “That means a total mitigation of 2.9 to 5.2 gigaton CO2, or an extra 1.3 to 3.6 gigaton CO2—so doing more REDD could close the gap.”
But this would have to be paid for by developed nations. Strassburg said that, so far, they have been wary of investing too much of their efforts and finances in REDD, in case developing nations fail to follow through with the reductions in deforestation. “They are cautious of this because they fear that if they increase their targets to accommodate more REDD and it doesn't deliver, they would have to provide this reduction from their own mitigation [at home], and that would be very costly."
To make up the shortfall, Strassburg suggests that “developed countries increase their targets by at least the size of the gap (1.9 Gt) or at most everything REDD could deliver (5.2 Gt). But they [should] make this extra commitment conditional on REDD being able to deliver it.” If not, he says, they wouldn't need to reduce this extra target internally, it would simply vanish.
“But REDD will deliver,” he added. “In this way they can sign an agreement here compatible with a 2°C target."