Rising methane could be a sign that Earth’s climate is part-way through a ‘termination-level transition’

Subject: Environment

Section: International conventions

Context:

Since 2006, the amount of heat-trapping methane in Earth’s atmosphere has been rising fast.

Methane emission:

Methane is a much more potent greenhouse gas than CO₂ but it lasts slightly less than a
decade in the atmosphere compared with centuries for CO₂.
Methane emissions threaten humanity’s ability to limit warming to relatively safe levels.
Sudden surges in methane marked the transitions from cold ice ages to warm interglacial climates.
Methane was about 0.7 parts per million (ppm) of the air before humans began burning fossil fuels. Now it is over 1.9 ppm and rising fast.
Unlike the rise in carbon dioxide (CO₂), methane’s recent increase seems to be driven by biological emissions, not the burning of fossil fuels.
- Roughly three-fifths of emissions come from fossil fuel use, farming, landfills and waste.
- The remainder is from natural sources, especially vegetation rotting in tropical and northern wetlands.

The methane record: 2006 to present:

In late 2006,atmospheric methane unexpectedly began rising.
Methane had risen fast in the 19th and 20th centuries but plateaued by the end of the 1990s. This rise was driven by fossil fuel emissions, especially from gasfields and coal mines.
During the 2020s the growth rate has become yet faster, faster even than during the peak of gas industry leaks in the 1980s.
Regions of high methane emission:
- Today’s growth seems to be driven by new emissions from wetlands, especially near the equator but perhaps also from Canada(beavers are methane factories which pull huge amounts of plant matter into ponds they’ve made) and Siberia.
Causes of emission:
- Increasing rainfall has made wetlands wetter and bigger while rising temperatures have boosted plant growth, providing more decomposing matter and so more methane.
- Emissions from huge cattle lots in tropical Africa, India and Brazil may also be rising and rotting waste in landfills near megacities like Delhi are important sources too.

Climate termination:

Methane is trapped in glaciers of polar regions. Global warming led glacier melting is causing sharp rises in atmospheric methane.
In the past few million years, Earth’s climate has flipped repeatedly between long, cold glacial periods, with ice sheets covering northern Europe and Canada and shorter warm interglacials.
These great climate flips that ended each ice age are known as terminations.
Around 131,000 years ago during Termination II, the British climate suddenly flipped from glaciers in the Cotswolds to hippopotami wallowing in what is now Trafalgar Square.
Full terminations take several thousands of years to complete, but many include a creeping onset of warming, then a very abrupt phase of extremely rapid climate change that can take a century or less, followed by a longer, slower period during which the great ice caps finally melt.

Is something dramatic underway?

Methane fluctuated widely in pre-industrial times. But its increasingly rapid growth since 2006 is comparable with records of methane from the early years of abrupt phases of past termination events, like the one that warmed Greenland so dramatically less than 12,000 years ago.
There is already lots of evidence that the climate is shifting:
- Atlantic ocean currents are slowing,
- Tropical weather regions are expanding,
- The far north and south are warming fast,
- Ocean heat is breaking records and
- Extreme weather is becoming routine.
In glacial terminations, the entire climate system reorganizes.
In the past, this took Earth out of stable ice age climates and into warm inter-glacials. But we are already in a warm interglacial.

Steps to curb the rise of methane emission:

Plugging leaks in the oil and gas industry,
Covering landfills with soil,
Reducing crop-waste burning.
Shooting the methane messenger won’t stop climate change, which is primarily driven by CO₂ emissions, but it will help.