 Forests play a critical role in climate change. Healthy forests absorb up to a third of all greenhouse gases, and deforestation causes about a fifth of all emissions, equal to the world's cars, trucks, planes and ships combined. As part of international efforts to slow the pace of global warming, nations are negotiating a mechanism that could see developed countries pay poorer ones to protect, restore and sustainably manage their forests. The scheme is known as REDD+, which stands for reducing emissions from deforestation and forest degradation. One of the technical challenges to implementing REDD is determining what your impact is. How much have you reduced your deforestation emissions? In order to do that, you have to be able to quantify carbon in your ecosystems. You have to be able to quantify the transfer of carbon and other greenhouse gases from your ecosystems to the atmosphere. To make it simplistic, we could compare this pit carbon stock to a bank account and calculate how much money is saved or lost during the year by making the balance of the transfers in and out of the account. Scientists from the Centre for International Forestry Research are conducting studies in Asia, Africa and Latin America on measuring and monitoring deforestation emission levels and effectiveness of REDD+, schemes. Particular types of forests like peat swamp forests and mangroves have become critical in certain countries' efforts to reduce their emissions. So it's technically complicated to determine how much area has been deforested but also, more importantly, how much carbon from the area that's been deforested ends up in the atmosphere. And that's where our work in the peatlands in particular is very important right now. Peatlands are some of the areas in Southeast Asia that are changing the most rapidly and we know the least about the carbon density. In Indonesia, most of our research focuses on peatlands. In their natural state, these ecosystems are waterlogged so you have a very low decomposition rate of the organic matter. So it accumulates and that's how the peat builds over millennia. And once you've drained, you reverse the situation and the carbon that has been accumulated starts decomposing and emitted as CO2 or methane. And every year that it's drained, an additional 8, 10, 12 tons of carbon per hectare goes from the peat to the atmosphere. So this is the peat soil. It's highly organic, like really little minerals in it. Considered peat soil when it has a carbon content above 60%. This is actually carbon and this is where most of the carbon is stored in this peat swamp ecosystem. So when peat swamp forests are converted, we estimate that about 60 to 80% of the emissions come from the peat. Therefore we have oriented our research in providing details and accurate data on these emissions from the peat. So the peat is pretty deep here. I think it's 5 meters. So as you go into the forest the peat starts to dome, forms a natural dome here. So here we've got quite a lot of peat. It's a good deep peat here. C4 researchers in the field are using sophisticated measurement techniques in virgin ecosystems as well as in converted areas of forests like oil palm plantations. Here the gas fluxes or gases that actually are emitted from this are relatively low. What we want to know is what happens if we drain this peat, take it out of its natural context. In the older palm oil plantation we're heading to the seafloor plot. Lodge scale, this palm oil plantation is vast. The area of peat that it's on is vast. Now if this process scaled up is happening across the tropics on a global scale this is actually going to have a really big impact on global warming. C4's research in mangrove forests is also shedding light on the importance of these coastal forest ecosystems. The mangroves are an interesting case because there's such a rapid rate of deforestation particularly here in Southeast Asia. We figure we're losing, we've already lost probably about 60 or 70% of the mangroves and we're losing them at 3-4% of the remaining mangroves per year. These mangroves have very, very deep sediments that are buried carbon for a long time and once you remove the vegetation the sediments begin to erode and that carbon gets resuspended in the water column in the coastal zones and can oxidize and then be transferred to the atmosphere. Results show that deforestation in mangroves generates as much as 10% of all emissions from deforestation globally. So much, much larger stores of carbon than we have in say tropical forest in the uplands or what we would normally think of as a tropical rainforest. We have 6, 8, 10 times as much carbon in these mangroves as we have in these types of forests so there's an awful lot that gets mobilized and then transferred back to the atmosphere. By gathering accurate data from the changes in greenhouse gas emissions between these natural environments and when converted for other uses information can be provided to governments and decision makers to assist in the way these forests are managed and for schemes to reduce carbon emissions like red plus. These are like the reference images, so the first images. So I will come back in two months, take the next set of images then two months afterwards, two months afterwards. This research is shedding light on other attempts to tackle climate change like the production of biofuels. If the products used in biofuels like palm oil come from plantations that were once forests this so-called green activity can have long lasting negative impacts for the climate. So the idea behind carbon debt is that once you deforest an area you've created large emissions. Now if you're going to do activities on that area and try and claim emissions reductions you actually have to first pay off that debt. The first set of emissions that came about from clearing the forest from converting those lands to this new land use. What you've got around is if you look to the horizon you've got this level area of trees literally all over and that's the palm oil plantation. And what was here before? Rainforest, it was all virgin rainforest before. So it's all been taken away from this. In the case of peatlands or mangroves the amount of carbon that's released by any other activity that you put on that land to try and reduce emissions it would take you at least 100 to 200, 250 years to repay that carbon debt. So for example in Sumatra there's an awful lot of conversion of peatlands that produce oil palm. The oil from palm can be used as biodiesel and this biodiesel is being sold as a biofuel, it's green it can help reduce fossil fuel emissions. But the case of peatlands in particular you have a very large biomass that you remove but then you go on and you emit 8 to 10 tons of carbon per hectare every year that you're producing oil palm on there from the peat decomposition. You have to then balance that against what's the fossil fuel offset. If you don't balance it you could have a negative you are having a negative impact on the atmosphere while you're telling yourself that you're actually having a positive impact on the atmosphere by not burning fossil fuels. And the atmosphere doesn't really care where the carbon comes from if it comes from fossil fuels or if it comes from peat it's still carbon in the atmosphere and you still get the global warming.