Methane Levels

Methane levels are soaring

graph of atmospheric methane over 800,000 years

Graph of methane levels (NASA)

The graph shows how methane levels in the atmosphere have moved over the last 802,000 years.

  • Each section on the timeline is 100,000 years.
  • Methane moved between 400 and 600 parts per billion (ppb) for about 700,000 years.
  • At the start of the industrial revolution, 1750, it was about 700 ppb.
  • By 2020 the levels had skyrocketted to 1,875 ppb.

The high methane levels are concerning as methane is a greenhouse gas that is about 25 times more potent than carbon dioxide.

Methane comes from many sources, including swamps, rivers, volcanoes, cattle, gas wells, gas pipelines, oil wells, coal mines, rubbish dumps, sewage treatment and rice fields.

The permafrost feedback cycle.

Higher global temperatures More melting of ice containing carbon
More greenhouse gassesMore methane & CO2 in the air

There are vast quantities of carbon (methane, dead plants & animals) trapped in permafrost, and global heating is thawing this permafrost. The thawing releases the trapped carbon, adding to the greenhouse gases in the atmosphere. If this feedback dominated, we would see:

  • higher global temperatures, causing
  • more melting of ice containing carbon (methane & dead plants & animals), releasing
  • more carbon dioxide & methane into the atmosphere, which closes the cycle by causing,
  • higher global temperatures.

This “self-reinforcing feedback cycle” increases (1) greenhouse gases, (2) global temperatures, and (3) melting permafrost.

This feedback is dangerous as permafrost holds such large amounts of carbon, about 1.6 times more carbon than our atmosphere. There are enormous areas of permafrost, e.g., about 25% of the northern hemisphere ground has permafrost under it. This permafrost feedback alone threatens our nurturing climate.

When this feedback is dominant:

  • higher global temperatures” cause “higher global temperatures, or
  • the hotter it gets, the hotter it will get.

It is a concern each element of this feedback is increasing: global temperature, atmospheric carbon dioxide, atmospheric methane, and melting of permafrost. This feedback cycle is active and supported by other feedback cycles and by human releases of greenhouse gases.

Arctic soil thaw may unleash runaway global warming (Scientific American, 2008)

This feedback is not reversible.

A decrease in temperatures might regenerate the permafrost. Still, the methane and carbon dioxide have escaped into the atmosphere, and the cooling alone would not move these greenhouse gases back into the permafrost.

Permafrost

People thought that permafrost was permanently frozen ground; however, global heating is thawing permafrost. The thawing can make the ground buckle and sink, causing trees to lean and fall.

Fallen trees after the permafrost melted in Fairbanks Alaska 2004
Fallen trees after the permafrost melted in Fairbanks, Alaska in 2004 (National Geographic: Broken link)

Thawing permafrost has caused severe damage to forests, buildings, roads, and sewerage.

Thawing permafrost destroyed this apartment building in Siberia.

The Earth’s methane levels are rising, and we do not know why
(New Scientist: May 2019)

The current warming could lead to methane release dominating our climate, and spiralling global warming, even if humans stopped burning fossil fuels.

Updated: 31 March 2022