Headline: Methane: A Short-Lived Gas With Far-Reaching Effects

The concentration of methane in the atmosphere has increased significantly in recent decades.
The concentration of methane in the atmosphere has increased significantly in recent decades. Shutterstock/Vaclav Volrab

In March 2024, leading politicians and industry experts gathered in Geneva to tackle one of the most pressing challenges of our time: methane emissions. The participants discussed available methods to reduce methane emissions as called for under the Global Methane Pledge, which aims to cut global methane emissions by at least 30 percent by 2030 compared to 2020 levels. In this blog post, we take a closer look at why methane emissions matter and how they could be reduced.

Climate change and its consequences challenge us to gain a better understanding of the interactions between human activities and the atmosphere. One key element in this context is methane (CH₄), a greenhouse gas whose global warming potential far exceeds that of carbon dioxide (CO₂). Its effect can be quantified by its Global Warming Potential (GWP), which indicates the climate impact of a gas compared to CO₂ over a certain period of time. It is important to note that methane is a short-lived greenhouse gas with an atmospheric residence time of around twelve years. While the GWP of methane over 100 years (GWP100) is 27.9, its GWP over 20 years (GWP20) is 81.2. In other words: methane has an immense warming effect over a short period of time. Overall, approximately 30 percent of current global warming can be attributed to methane.

Methane’s global warming potential: two perspectives

The choice of assessment scale that is applied to a greenhouse gas has far-reaching implications for both climate strategies and the prioritization of measures aimed at reducing emissions. Whether these should focus primarily on the short-term effects of emissions over the coming decades, or their long-term effects over the course of a century, is highly contested.

CO2 and CH4 emissions as CO2 equivalents; includes a breakdown of their global warming potentials: GWP 20 and GWP 100.

While valuable insights can be gained from both observation periods, GWP100 has become the established benchmark in policy and scientific debates. But focussing on this long-term perspective risks neglecting the near-term effects of certain gases, such as methane.
The GWP20 scale provides an urgently needed focus on the short- to medium-term impacts of greenhouse gases and is especially relevant when it comes to short-lived greenhouse gases such as methane. In this perspective, rapid and targeted measures to reduce methane emissions could make a significant contribution to slowing global warming. This is particularly important with regard to the goals of the Paris Agreement.

Methane and the Paris climate goals 

In the period from 2011 to 2020, the average temperature of the Earth's surface was 1.1 °C above the average for the years 1850 to 1900. It is predicted that global warming could exceed the 1.5 °C threshold established under the Paris Agreement between 2030 and 2052 if the current rate of temperature increase continues. Current estimates suggest that global warming caused by human activities will increase by around 0.2 °C per decade. Modelling of future scenarios shows that to meet the 1.5 °C target, global emissions of CO₂ related to human activities must be reduced by around 45 percent by 2030 compared to 2010 levels, with the aim of achieving net zero emissions by 2050.

In addition to its role as a greenhouse gas, methane is a precursor for ozone, an irritant gas that has significant negative effects on the health of humans and animals as well as plant vitality. Research suggests that a 45 percent reduction in methane emissions could prevent up to 255,000 premature deaths annually and reduce asthma-related hospitalizations by 775,000, while increasing global crop yields by around 26 million tons per year. A report by the Global Methane Alliance notes that a significant share of this reduction could be achieved with available technologies, with 60 percent of these interventions assessed as cost-effective. In particular, 50 percent of these measures would deliver financial gains, with the savings achieved exceeding associated costs.

In order to achieve the ambitious climate targets adopted under the Paris Agreement, it is essential that climate strategies address the full range of greenhouse gases, including methane. Moving GWP20 to the centre of debate could help to refocus climate policy on strategies that prioritize and deliver near-term measures to reduce methane emissions.

Current developments and the role of agriculture

Current climate scenarios predict an 8 percent increase in global methane emissions between 2020 and 2030. Three sectors account for the bulk of methane emissions worldwide: fossil fuels (~35 percent), agriculture (~40 percent) and waste (~20 percent). Within agriculture, livestock farming – and especially cattle – is the most significant source of methane emissions. In Germany, the agricultural sector accounts for around 75 percent of methane emissions (these figures are for domestic production, with imported goods playing a lesser role).
 

Methane emissions in Germany by sector, 1990 – 2022.
T. Gentsch, based on UBA


Effective strategies for reducing emissions of short-lived greenhouse gases in agriculture call for both technical solutions and changes in lifestyles, including reducing food waste and promoting a more sustainable consumption of animal products. The challenge lies in how we go about implementing such measures. While forcing people to change their lifestyles is probably impracticable, developing intelligent incentive systems and providing transparent information on products can help people to purchase more consciously. In Germany, the Citizens' Assembly on Nutrition has recommended the introduction of a state-backed sustainability label for all products sold within the EU so that consumers can identify products that are harmful to the climate or pose health risks. The assembly also recommended a sales tax reform that would exempt unprocessed, healthy foods such as fruit, vegetables and water from VAT, while increasing VAT to 19 percent on products with a high sugar content and meat produced using farming methods that are less animal-friendly (levels 1 and 2).

A call to reassess methane

The consideration of methane emissions and their near-term warming potential (GWP20) is crucial for the development of realistic climate strategies. Recent scientific findings emphasise the urgent need to significantly reduce methane emissions. This is essential not only to meet the ambitious goals of the Paris Agreement, but also to avoid harms to human, animal, and plant health. Measures to reduce methane emissions can reduce concentrations of harmful ground-level ozone and support the transition to a healthier diet. These findings should prompt policymakers to pursue and implement initiatives that will reduce methane emissions in order to address both environmental and health goals.
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