Prepared by Kim Perrotta MHSc, May 15, 2021
A new United Nations report, Global Methane Assessment, notes that the most cost-effective way to limit global warming to 1.5°C can also produce significant and immediate public health benefits.
The concentration of methane in the atmosphere has been rapidly increasing since the 1980s. Methane, which is the main component in natural gas, is a short-lived climate emission that stays in the atmosphere for about 10 years. But it is also a potent greenhouse gas (GHG) that is many times more powerful than carbon dioxide as a warming agent.
The Intergovernmental Panel on Climate Change (IPCC) has identified a 40 to 45% reduction in global methane emissions by 2030 (i.e., about 180 million tonnes per year) as the most cost-effective strategy for limiting global warming to 1.5°C. Because methane is a short-lived but potent GHG, reduced emissions can rapidly reduce the rate of global warming and help limit dangerous climate feedback loops. This strategy would also produce significant and immediate public health benefits.
Public Health Benefits
The UN report notes that methane is a precursor for ground-level ozone, a common air pollutant that increases emergency room visits, hospital admissions and premature deaths. On a global scale, approximately 500,000 premature deaths per year can be attributed to air pollution resulting from methane emissions related to human activities.
The UN assessment found that every million tonnes (Mt) of methane reduced:
- Prevents approximately 1,430 air pollution-related premature deaths per year; 740 from respiratory disease and 690 from cardiovascular disease;
- Prevents approximately 4,000 asthma-related accident and emergency room visits and 90 hospital admissions per year;
- Avoids losses of 145,000 tonnes of wheat, soybeans, maize and rice due to ozone exposure every year;
- Avoids the loss of about 300 million hours of work globally due to extreme heat each year.
In North America, where it is estimated that 34.7 million tonnes (Mt) of methane are being emitted each year from human activities, methane emissions may be responsible for up to 49,000 premature deaths and 139,000 asthma-related emergency room visits each year from air pollution alone.
Globally, more than half the methane emissions stem from human activities in three sectors: 35% from fossil fuels (the extraction, processing and distribution of oil, gas and coal), 20% from waste (landfill and wastewater) and 40% from agriculture (livestock manure and digestion gas, and rice cultivation). In North America, 41% of emissions are from fossil fuels, 28% from livestock and 21% from waste.
The UN report finds that the targeted measures needed to reduce global methane emissions by 30% (about 120 Mt/yr) by 2030 are readily available. About 60% of these measures have low mitigation costs and over 50% would pay for themselves quickly by saving money. The greatest potential for cost savings exists within the oil and gas sector where captured methane adds to revenues. When all market and non-market impacts are considered, nearly 85% of the targeted measures have benefits that outweigh the net costs. They also reduce costs, increase efficiency, encourage innovation and create jobs.
The UN report indicates that another 15% of methane reductions (about 60 Mt/yr) could be achieved by 2030 with additional measures such as behavioural changes. It notes that “without relying on massive-scale deployment of unproven carbon removal technologies, expansion of natural gas infrastructure and usage is incompatible with keeping warming below 1.5°C.”
Reference: United Nations Environment Programme (UNEP) and the Climate and Clean Air Coalition. 2021. Global Methane Assessment: Benefits and Costs of Mitigating Methane Emissions | UNEP – UN Environment Programme.