What if you thought the car you drove got 40 mpg but I told you that it only gets 24 mpg? What if that ice cream sandwich that you treat yourself to after dinner had not 300 calories but 500? What if leaving your air conditioner on during the day cost not $40 a month but $67? Would any of these things make you rethink your purchasing decisions or habits?
That’s a bit similar to the finding of a new report just published, authored by Kimberly Carlson of the University of Minnesota Institute on the Environment and my colleague and I here at UCS. In it, we found that carbon losses from oil palm plantations on tropical peatlands may be significantly higher than some previous official estimates.
Instead of around 12 tons of carbon lost per hectare per year, our research, which takes a look at numerous studies measuring carbon emissions from drained peat soils, finds that a more likely estimate is around 20 tons of carbon lost per hectare per year. The difference is roughly equivalent to the carbon emissions from driving 70,000 miles in a car. So if the plantation contains many thousands of hectares, well – that adds up pretty quickly.
Why this discrepancy?
To put it simply, there is a lot we don’t know about tropical peat emissions. We do know that peat soils have been built up over thousands of years and are part of a delicate ecosystem. And we also know that peat soils are increasingly being drained for plantation agriculture, particularly in Southeast Asia. We know that peat soils are extremely carbon-rich and when drained and exposed to air they release carbon dioxide into the atmosphere, contributing to global warming.
But peatlands are not all drained to the same level. Some may leave only 50 cm exposed to air, and others a full meter or more. Our paper aggregated multiple studies, meaning our analysis will likely come closer to an average value than any one study. And we estimate how water table depth affects carbon emissions.
Our research finds that other estimates, such as the one I referenced above by the International Panel on Climate Change’s 2013 Supplement to the 2006 Guidelines for National Greenhouse Gas Inventories, may be underestimating emissions on oil palm plantations.
So all this sounds super technical, and to a degree it is. But it’s also fairly intuitive. Try watching this video for a simple explanation (with illustrations and pictures!)
So – some of you would still eat that ice cream sandwich (I know I likely would). But I might consider a different form of transportation for my commute or using a fan during the day to circulate air and only use the air conditioner when I’m in the apartment. The fact of the matter is that knowledge is power.
As people make decisions about land use in the context of climate change, our findings show that some may be underestimating just how much attention should be paid to agricultural plantations on peatlands. They lend additional weight to the argument that tropical peatlands are more important than ever to conserve, especially from a global warming perspective.