Jonah Busch, from Conservation International, and his colleagues, have compared six different schemes that have been proposed for Reducing Emissions from Deforestation and Forest Degradation (REDD). For each REDD scheme they model the likely reduction in emissions and the economic cost.
At one end of the spectrum lies a scheme where countries are given credits and incentives to reduce deforestation, based on historical reference levels of deforestation. At the other end of the scale is a "cap and trade" style scheme where credits are given for reduction in deforestation and penalties are issued for increases in deforestation. The schemes in between use varying reference levels for deforestation and apply different weightings to the credits for reducing deforestation and for maintaining standing forest stock.
In principle a REDD scheme could cut out all deforestation emissions and reduce global greenhouse emissions by one-fifth, if it were able to stop deforestation entirely. In practice the model results produced by Busch and his colleagues suggest that the most effective REDD scheme is capable of cutting deforestation emissions by around 83%.
The findings, published in Environmental Research Letters, show that all REDD schemes have potential to mitigate climate change, but the degree of mitigation will vary, according to which scheme is adopted.
Busch and his colleagues showed that the least effective REDD scheme was the one based on historical reference levels of deforestation, with no penalties for increasing deforestation levels. "This scheme provides incentives only for reducing deforestation, but not for maintaining standing forests," Busch told environmentalresearchweb.
Their model showed that this REDD scheme tends to shift deforestation to other countries, in response to higher prices for agricultural and timber commodities – a phenomenon known as "international leakage". By contrast, all of the other designs have features in place to minimise such leakage, by providing incentives to countries with low deforestation rates to stabilize and maintain low rates of deforestation.
Nonetheless, the REDD scheme based on historical deforestation levels still has the potential to almost quarter the emissions from deforestation compared with a "business-as-usual scenario", their model shows.
The cap-and-trade-based REDD scheme produced the greatest reduction in emissions. "It is the only design that uses sticks in addition to carrots," said Busch. "A country that emits less than its cap would receive payment; a country that emits more than its cap would be penalized." Such a scheme would reduce emissions to around one-sixth of the "business-as-usual scenario", their model showed. What's more, a cap and trade system is the most cost effective, in terms of emissions reduced per dollar spent.
But there's a snag. Unfortunately the cap and trade style scheme is also likely to be the least palatable politically. "Developing countries are reluctant to take on caps in the near term," explained Busch. Meanwhile, a REDD scheme based on historical deforestation levels, and without penalties, is simple to implement and requires the least political negotiation. "The other four schemes represent a compromise between effectiveness and political viability, and I think we'll see one of these four designs chosen," said Busch.