Methane is 25-28 times more potent as a greenhouse gas than CO2, and it’s the second most common greenhouse gas at 16% of the total of all greenhouse gases (CO2 is 76%).
It does occur naturally, but a gigantic store of the Earth’s methane is locked in polar ice. 60bn tonnes of methane is locked in the Arctic ice alone (with 560bn tonnes of carbon also locked in there). So as the Earth warms and that melts (Greenland alone loses 6 Olympic size swimming pools of melted ice as water every second), the more methane (and carbon) is released.
Also, as non-saline ice melts into saline waters, the less saline the oceans become and the cooler the oceans become. As the oceans lose warmth and salinity, their currents slow (which comes with huge problems itself away from greenhouse gases!). Also more methane is released from ocean floors (where it is also locked) the cooler oceans become.
Livestock farming (which does produce a lot of CO2 and another potent greenhouse gas, nitrous oxide) also creates a huge amount of methane from cattle eructation. It’s estimated that 40% of the Earth’s released methane comes from livestock farming.
There are innovations to capture the eructed methane producing ruminants from cattle, but the technology is decades behind where it needs to be. As I’ve said before, it’s all good us all saying things like “human ingenuity will come up with solutions”, but the solutions aren’t backed by governments or by enough investment to make a difference, and climate change is moving ever further away.
Reducing meat consumption will be the quickest way to reducing this from livestock but how much of the world will do that?