INTRODUCTION

The Global Methane Pledge was ratified at the end of 2021. While intense discussion of its significance dominated the climate discourse in North America and Europe, the reception of the Pledge in Southeast Asia was lukewarm. This paper aims to help the policy community understand four major aspects concerning methane emissions: basic science, global ambition, regional trends, and sector challenges.

In 1990, the Intergovernmental Panel on Climate Change (IPCC) published its First Assessment Report, in which scientists stated with certainty that human-caused greenhouse gases were accumulating in the atmosphere. One of these significant gases was methane. Since then, global methane emissions have increased by 17.4 per cent, reaching 8.3 billion tCO2e in 2018. Unlike carbon dioxide, which can persist in the atmosphere for hundreds of years, methane only lasts around 12–15 years before being broken down. Despite being emitted in smaller amounts, methane is a highly potent greenhouse gas compared to carbon dioxide. In fact, methane has been responsible for about 30 per cent of global temperature rise since the industrial revolution. Its relative potency is measured by its Global Warming Potential (GWP), a metric that reflects the global warming impact of each type of greenhouse gas relative to carbon dioxide over a particular time period. Over a period of 100 years, methane has a GWP of 27.9 —that is, 1 kg of methane has the same warming impact as 27.9 kg of carbon dioxide. Global greenhouse gas emissions measured in carbon dioxide equivalents consist of 74.4 per cent carbon dioxide and 17.3 per cent methane, making them the two most important greenhouse gases to tackle. Across a shorter time horizon of twenty years, methane has an even higher GWP of 81.2, making it particularly impactful on warming in the near future. Methane is thus a crucial factor in this decade’s challenge of achieving immediate and drastic reductions in greenhouse gas emissions.

SOURCES OF METHANE COME FROM VARIOUS SECTORS

Around 60 per cent of global methane emissions are human-caused, and this comes largely from agriculture, fossil fuels and waste. Agricultural emissions are mainly attributed to enteric fermentation (digestive processes in animals like cattle) and manure in livestock as well as rice cultivation, where methane-emitting bacteria grow in flooded rice paddies. In this article, estimates of animal agricultural production exclude eggs, the production of which does not have significant methane emissions.