Wetlands in the icy Arctic have begun releasing 9% more planet-warming methane in the past two decades: study

While we remain focused on livestock and fossil fuel production as major sources of methane emissions, there is another gargantuan source of the greenhouse gas that has continued to worry climate scientists for years: natural wetlands.

These vast landscapes hold the dubious distinction of being Earth's biggest natural emitter of methane, and rising temperatures have only begun to accelerate this process. Now, research has revealed that the Boreal-Arctic wetlands may have been emitting 9% more methane in the past two decades.

What’s the big deal with methane?

While headlines may remain fixated on carbon dioxide (and understandably so), there is another accomplice aiding the gas in heating our planet. Trapping 30 times more heat than carbon dioxide despite lingering in the atmosphere for a shorter period, methane is a far more potent greenhouse gas. Studies have also shown that about a quarter of our global warming can be attributed to methane, and we will need to cut its levels by nearly half to achieve the 1.5°C warming target laid down by the Paris Agreement.

Most of our methane emissions come from the energy sector, along with decaying waste and animal agriculture. However, natural wetlands, consisting of waterlogged soils which earlier acted as massive carbon sinks, are also responsible for about a third of total methane emissions in the atmosphere. Accurately quantifying these emissions in the icy Boreal and Arctic permafrost has been a challenge due to the vastness and often inaccessible nature of wetland ecosystems.

Wetlands on fire

Wetlands are teeming with microbes and support vibrant plant life. As temperatures in the Boreal-Arctic wetlands have begun to rise at a concerning rate — four times the global average — scientists have begun to raise the alarm about its potential consequences for our planet.

Rising temperatures have a few key effects. Firstly, they accelerate the activity of microbes responsible for producing methane. Secondly, they thaw frozen soil and increase rainfall, leading to more waterlogged areas, creating ideal conditions for these microbes to thrive. Finally, when plants inevitably become more productive due to rising temperatures, they release more carbon into the soil, which fuels the methane-producing microbes, creating a feedback loop that further amplifies emissions. This directly influences the amount of methane released.

The wetland-methane connection

The study revealed that between 2002 and 2021, wetlands in the Boreal-Arctic regions released an average of 20 teragrams of methane annually — an amount equivalent to the weight of around 300 Statue of Unity’s! In addition to a 9% increase in emissions since 2002, the team found that 2016 — the warmest year on record — was also a year with the maximum amount of wetland emissions. This suggests the massive influence methane from wetlands can have on the planet’s temperatures.

The researchers also managed to identify two "hotspot" areas within the Boreal-Arctic region which regularly contribute a staggering half of the average annual emissions. Understanding these hotspots is crucial for targeted mitigation efforts and future monitoring endeavours.

The findings of this research have been published in Nature Climate Change and can be accessed here.