Response to articles in The Guardian and other media on the study “Pervasive over-crediting from cookstove offset methodologies” by Gill-Wiehl et al., published in the journal Nature Sustainability in January 2024.

myclimate has analysed the study published in Nature Sustainability by Gill-Wiehl, Kammen, and Haya on the effectiveness of cookstove projects and the integrity of the emission reduction certificates issued for them. Although myclimate expressly welcomes new research approaches aimed at improving project quality, the climate protection organisation based in Zurich regrets the simplified presentation of the projects and the fundamental methodological shortcomings of the study. The results of the study, which assume a massive over-crediting of cookstove projects, are therefore not considered acceptable by myclimate.

Photo: myclimate

The development of climate protection projects that are financed via the voluntary markets is extremely complex. The Foundation myclimate has over 20 years of experience in this area and in-depth knowledge of effective, high-quality cookstove projects. As a result, myclimate is more than familiar with the challenges and difficulties that such projects can entail and the uncertainties associated with calculating the emission reductions achieved through project activities.

The following statement on the study “Pervasive over-crediting from cookstove offset methodologies” by Gill-Wiehl et al. emphasises that we do not agree with the results and methodology of the study on several crucial points. myclimate therefore disagrees with the study’s generalised conclusions, in particular the alleged massive over-crediting of emission reductions.


The main criticisms levelled by myclimate are:

  • The study uses values from the literature for individual factors in calculating specific CO2 savings (utilisation rates, firewood requirements, etc.) as comparative values. It assumes that these values are better or more accurate than the data collected through the annual monitoring of certified projects.
  • The paper identifies differences, but completely overlooks the fact that the projects may have better factors than the – sometimes vastly outdated – mean values. Performancebased crediting mechanisms are used, for example, to train users in projects supported by myclimate or to carry out maintenance programmes for the cookers.
  • These instruments are omitted from the comparative values on which the study focuses. The underlying data is therefore distorted, and the study exhibits a “data bias”.
  • The success of a project always depends on many local factors. From a methodological point of view, it is generally very questionable to use a global average from the literature (which covers numerous projects from Asia, Africa and South America with a data basis dating back to 2009) as a reference for project-specific factors. The study thus contradicts itself by emphasising the need to take greater account of local conditions and contexts when evaluating climate protection projects.
  • The method used to measure fuel consumption in myclimate projects for more efficient cookstoves is always based on the most conservative approach. Realistic measurements are made by conducting kitchen performance tests to calculate both the baseline and the actual emissions, rather than relying on default values. This allows for a more reliable and representative estimate of actual fuel consumption under varying conditions, such as different climates and cooking habits.

Above and beyond the CO2 savings, the cookstove projects that myclimate has long supported have had a very positive impact on the lives of many people. Nevertheless, myclimate emphasises the importance of a differentiated view and the need for continuous improvement and adaptation of methods in climate protection. We recognise the general points of criticism and encourage the Voluntary Carbon Markets Standard (VCM), the other standards and project developers to take these criticisms seriously.

At the same time, we believe that this study, while generally highlighting relevant opportunities for improvement, vastly overestimates the potential for over-valuation in biogas digester projects. We will continue to work towards a better understanding of the factors influencing the success of a project.

The aim of myclimate is to find the right balance between robust and conservative estimates of all values and applicability (costs and benefits) on the ground to ensure that as many people as possible have access to clean and climate-friendly cooking.

You can find the entire statement here.


Further Links:
Gold Standard assessment
Open letter on the study from other experts, researchers and project developers
The study by Gill-Wiehl et al.
Article in The Guardian

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