A new study has found that increasing the cost of carbon credits is required to make tropical forest conservation a viable alternative to the spread of rubber plantations in Cambodia.

Researchers in the new study argue that increasing payments for carbon credits is needed to create incentives for the protection of tropical forests in Southeast Asia, including in Cambodia, against further deforestation to make way for rubber.

In a statement, the researchers of the study published Friday in Nature Communications say payments are currently too low and “do not pay enough to compete with profits of rubber plantations”.

Payments for carbon credits currently range from $5 to $13 per tonne of carbon dioxide on carbon markets. Prices ranging from $30 to $51 per tonne would be needed to make conservation economically competitive with converting forest into rubber plantations, they found.

“To defend forests from rubber, either carbon prices must be increased, or other strategies are needed, such as corporate zero-deforestation pledges, and governmental regulation and enforcement of forest protection,” the study reads.

In Cambodia, rubber cultivation areas increased by 175 percent between 2009 and 2013, for a total of 328,800 hectares. By April 2017, more than 430,000 hectares had been converted to cultivate rubber.

Sarah Milne, with the Australian National University, agreed that carbon payments are now too low “to make a difference to the deforestation drivers”, but added that the biggest question is whether or not the authors had taken a look at the political and economic forces at play in the expansion of rubber in Cambodia – such as if government officials, tycoons, logging contractors, or the military are involved.

“And is it appropriate or even possible to inject carbon finance into such a political economy, and expect it to make a difference to deforestation rates?” she wrote in an email.

Eleanor Warren Thomas, the study's lead researcher, said the study did not dive into the details of local forces at play.

“However, what we looked at was trying to quantify how important rubber plantations are as a driver of deforestation in Cambodia, and whether carbon payments could offer an attractive alternative from a cost-benefit point of view,” she said.

Suwanna Gauntlett, head of Wildlife Alliance, agreed that increasing the payments would be a good incentive as payments currently can go as low as $2 dollars per tonne of carbon dioxide in the trading market.

“It’s always a buyers’ market,” she said, especially given that companies are under no legal obligation to buy credits.

Additional reporting by Erin Handley