Study finds GHG emissions associated with palm oil production have been significantly underestimated; implications for carbon intensity of biofuels as well as biofuel policies in Europe
A new study on greenhouse gas (GHG) emissions associated with the conversion and degradation of peatland in palm oil plantations in Southeast Asia has determined that past studies have generally significantly underestimated emissions associated with palm oil grown on peatland. This has resulted in underestimation of the indirect land use change emissions from many biofuels derived from palm oil, the study concluded.
The study led by a team from the University of Leicester (UK) suggested that 86 Mg CO2-eq ha-1 yr-1 (over 50 years) or 100 Mg CO2-eq ha-1 yr-1 (over 25 years) represent the best available estimates of typical emissions from peat decomposition in palm plantations.
A number of recent publications have addressed the GHG emissions associated with land use conversion of tropical peat swamp forest to OP [oil palm] plantation. All conclude that while carbon losses from biomass replacement and land clearance are considerable, it is the large and sustained CO2 emissions from drained peat that contribute most to overall emissions and biofuel carbon debts. The values used to estimate peat CO2 emissions have a wide range (19 to 115 Mg CO2-eq ha-1 yr-1) and are derived from a variety of sources, including IPCC defaults and a limited number of scientific studies. Dependency on a limited number of flux studies, combined with inappropriate upscaling, has resulted in systematic underestimation of GHG emissions from OP plantations on tropical peat.
...In terms of an uncertainty range, we suggest that likely peat CO2 emissions should be represented by the minimum and maximum values of 54 to 115 Mg CO2-eq ha-1 yr-1 for the typical OP drainage depth range of 0.6 to 0.85 m. It should be noted that none of these values explicitly consider local factors promoting GHG emission other than water depth (e.g., fertilization, land use history) or regional geographical variations. The adoption of the best estimate and full uncertainty range suggested here will, however, lead to reduced uncertainty in future assessments conducted at the regional scale.
The majority of previous studies aiming to assess GHG emissions from OP production systems on tropical peatlands have at best based their analyses on values below or towards the lower end of this range, and in all likelihood have significantly underestimated CO2 emissions from drained peats. In terms of biofuel production, it is likely that the true magnitude of the biofuel carbon debt for OP feedstocks produced on tropical peatlands is more substantial than has been previously assumed.—Page et al.
Tropical peatland is one of the Earth’s most spatially efficient carbon sinks and largest long-term repositories of terrestrial organic carbon. Development of tropical peatland for agriculture and plantations requires radical changes in the vegetation cover. These changes reduce or remove the carbon sink capacity of the peatland system by:
lowering of the peat water table, which ensures continuous aerobic decomposition of organic matter (plant litter and peat), resulting in high peat surface CO2 emissions; and
greatly reducing or stopping carbon inputs to the peat from biomass.
The study was conducted for the International Council on Clean Transportation (ICCT), which wished to assess the greenhouse gas emissions associated with biodiesel production. Biodiesel mandates can increase palm oil demand directly (the European Biodiesel Board recently reported big increases in biodiesel imported from Indonesia) and also indirectly, because palm oil will replace oil from rapeseed or soy in food if they are instead used to make biodiesel.
The University of Leicester researchers carried out the first comprehensive literature review of the scale of greenhouse gas emissions from oil palm plantations on tropical peatland in Southeast Asia. In contrast to previous work, this study also provides an assessment of the scientific methods used to derive emissions estimates.
The team discovered that many previous studies were based on limited data without appropriate recognition of uncertainties and that these studies have been used to formulate current biofuel policies.
The findings have been published as an International White Paper from the ICCT: Review Of Peat Surface Greenhouse Gas Emissions From Oil Palm Plantations In Southeast Asia. This ICCT paper was produced as a consultancy report; a scientific version of the research will be submitted for publication in the peer-reviewed academic literature.
Although the climate change impacts of palm oil production on tropical peatland are becoming more widely recognized, this research shows that estimates of emissions have been drawn from a very limited number of scientific studies, most of which have underestimated the actual scale of emissions from oil palm. These results show that biofuels causing any significant expansion of palm on tropical peat will actually increase emissions relative to petroleum fuels. When produced in this way, biofuels do not represent a sustainable fuel source.—Ross Morrison, of the University of Leicester Department of Geography
Growth in palm oil production has been a key component of meeting growing global demand for biodiesel over recent decades. This growth has been accompanied by mounting concern over the impact of the oil palm business on tropical forests and carbon dense peat swamp forests in particular. Tropical peatland is one of Earth’s largest and most efficient carbon sinks. Development of tropical peatland for agriculture and plantations removes the carbon sink capacity of the peatland system with large carbon losses arising particularly from enhanced peat degradation and the loss of any future carbon sequestration by the native peat swamp forest vegetation.
Although there have been a number of assessments on greenhouse gas emissions from palm oil production systems, estimates of greenhouse gas emissions from land use have all been based on the results of a limited number of scientific studies. A general consensus has emerged that emissions from peat degradation have not yet been adequately accounted for.
The results of the Leicester study are important because an increase in the greenhouse gas emissions associated with biodiesel from palm oil, even if expansion on peat only occurs indirectly, could negate any savings relative to the use of diesel derived from fossil fuel.
The likely underestimation of emissions from peat in previous assessments has implications for the results of the modeling of the land use impacts of biofuel policies, and hence potentially for the policies themselves. The underestimation or non-inclusion of peat emissions from oil palm expansion in most previous modeling of the iLUC [indirect land use change] impacts of biofuels was noted by JRC (2010). Based on this review, the value of 57 Mg CO2 ha-1 yr-1 proposed by JRC (2010) is also an underestimate (although we note that these authors also propose an upwards revised value of 112 Mg CO2 ha-1 yr-1, which may be an overestimate). This underestimation of peat GHG emissions in the iLUC modeling literature may have contributed significantly to an underaccounting of the indirect land use change GHG emissions of biodiesel, and in particular of biodiesel made from palm oil.
For instance, Al-Riffai et al. (2010) used two emission values—5 and 40 Mg CO2-eq ha-1 yr-1, based on IPCC (2006), and Wetlands International (2009a), averaged to 22.5 Mg CO2-eq ha-1 yr-1—to find that peat emissions contributed around 4 g CO2-eq MJ-1 to the carbon intensity of palm biodiesel, and perhaps under 1 g CO2-eq MJ-1 to the carbon intensity of other biodiesel.
With the central value suggested here, those values would have been more like 19 and 5 g CO2-eq MJ-1, respectively. JRC (2010) noted that the estimate of 18% of OP expansion occurring at the expense of peat had also been set too low by Al-Riffai et al. (2010). In that case, correcting up to 33% as suggested by JRC (2010) would create a compound effect and further increase the reported peat contribution to the biodiesel carbon intensities to 35 and 9 g CO2-eq MJ-1 for palm oil biodiesel and other biodiesel, an intensity increase of 31 and 8 g CO2-eq MJ-1, respectively. To place this in context, an increase in carbon intensity of 31 g CO2-eq MJ-1 would subtract 37% from the reportable carbon savings of palm oil biodiesel used in the European Union.—Page et al.
If these improved estimates are applied to recent International Food Policy Research Institute (IFPRI) modeling of the European biofuel market (LaBorde, 2011), they imply that on average biofuels in Europe will be as carbon intensive as gasoline, with all biodiesel from food crops worse than fossil diesel and the biggest impact being a 60% increase in the land use emissions resulting from palm oil biodiesel. Bioethanol or biodiesel from waste cooking oil, on the other hand, could still offer carbon savings.
This outcome has important implications for European Union policies on climate and renewable energy sources.
We are very excited by the outcomes of our research—our study has already been accepted and used by several scientists, NGOs, economists and policy advisors in Europe and the USA to better represent the scale of greenhouse gas emissions from palm oil biodiesel production and consumption.
The findings of this research will be used by organisations such as the US Environmental Protection Agency, European Commission and California Air Resources Board to more fully account for greenhouse gas emissions and their uncertainties from biofuel produced from palm oil. This is essential in identifying the least environmentally damaging biofuel production pathways, and the formulation of national and international biofuel and transportation policies.—Dr. Sue Page, Reader in Physical Geography at the University of Leicester
The research was commissioned by Dr. Chris Mallins of the ICCT. Other contributors to the work were Professor Jack Rieley of the University of Nottingham and chair of the scientific advisory board of the International Peat Society (IPS), Dr. Aljosja Hooijer of Deltares in the Netherlands, and Dr. Jyrki Jauhiainen of the University of Helsinki.
Peat degradation under oil palm is a major source of emissions from biodiesel production. Recognizing that emissions are larger than previously thought will help regulators such as the US Environmental Protection Agency (EPA), European Commission (EC) and California Air Resources Board (CARB) identify which biofuel pathways are likely to lead to sustainable greenhouse gas emissions reductions.—Dr Chris Malins of the ICCT
David Laborde (2011) Assessing the Land Use Change Consequences of European Biofuel Policies
Page, S. E., Morrison, R., Malins, C., Hooijer, A., Rieley, J. O. & Jauhiainen, J. (2011). Review of peat surface greenhouse gas emissions from oil palm plantations in Southeast Asia (ICCT White Paper 15). Washington: International Council on Clean Transportation