Many human activities lead to methane being released into the atmosphere. Agriculture, landfills, wastewater, and fossil fuel production and distribution are the biggest contributors. These make up roughly 60% of global methane emissions, and natural sources account for the remaining 40% of emissions.

Like carbon dioxide (CO 2 ), methane is a potent greenhouse gas, estimated to be responsible for more than 40% of recent global warming. However, methane has an atmospheric lifespan (the time it takes to breakdown into something else) of only about 12 years, much shorter than CO 2 .

This means that cutting methane emissions can have a quicker response than CO 2 on slowing global temperature rise.

Methane also contributes to ground-level (tropospheric) ozone, a dangerous air pollutant. Many people know that the ozone layer in the upper atmosphere helps protect us from harmful ultraviolet rays from the sun, and efforts have been made to protect the ozone layer after decades of decline.

However, ozone released at ground level can be very harmful because it reacts aggressively with lung tissue, causing respiratory illnesses in humans as well as damaging crops and natural vegetation. Recent estimates suggest that roughly 1 million people die prematurely every year because of exposure to harmful tropospheric ozone, 24,000 of those in the EU.

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