Delaying methane mitigation increases risk of breaching Paris Agreement climate goal, study finds

A key element of the 2015 Paris Agreement, a legally binding international treaty on climate change, is the commitment to limit average global temperatures increases to well below 2°C above pre-industrial levels, and pursue efforts to limit global warming to 1.5°C above pre-industrial levels. This requires reaching net-zero CO₂ emissions by or around 2050 -- and deep reductions in methane and other emissions.

The study, published in Nature's Communications Earth & Environment, suggests that global warming levels, relative to the pre-industrial period, could be limited below 2°C if global-scale methane mitigation efforts are initiated before 2030.

However, delaying methane mitigation to the year 2040, or beyond, would increase the risk of global warming levels exceeding 2°C above pre-industrial levels, even if net-zero carbon dioxide (CO₂) emissions were achieved.

Methane is second only to CO₂ in contributing to global temperature increases over the last two centuries. Over the past 40 years, more than 60 per cent of global methane emissions have emerged because of anthropogenic activities such as fossil fuel exploitation, livestock production, agriculture, and waste.

"We emphasize that actions associated with the Global Methane Pledge should not be delayed, because every year of delayed methane mitigation implies further global warming," says Kirsten Zickfeld, distinguished professor of climate science, director of SFU's Climate Research Lab, and member of the research team.

"While policymakers now accept the need for urgent methane mitigation, it is necessary to emphasize the importance of immediate mitigation to comply with the temperature goal in the Paris Agreement -- particularly taking into account potential Earth system feedbacks," says Claude-Michel Nzotungicimpaye, former PhD student at SFU, researcher on Zickfeld's team, and the study's lead author.

In their study, Zickfeld's team uses an Earth system model with a coupled methane cycle to examine the importance of immediate versus delayed methane mitigation to fulfil the 2°C threshold. They investigate the role of feedback in carbon and methane cycles in the timing of methane mitigation to achieve the Paris Agreement climate goal, as well as the long-term climate impacts of delaying or failing to mitigate methane in the current century, which has not previously been studied.

As per the group's findings, every 10-year delay in methane mitigation will result in an additional peak global warming temperature of approximately 0.1°C.

Their results emphasize the need for immediate cuts in anthropogenic methane emissions across the world, along with stringent CO₂ mitigation, to increase the likelihood of holding the rise in average global temperatures to well below 2°C above pre-industrial levels.