Greenhouse gas emissions from soils increased by earthworms: opening a can of worms | Carbon Brief
Humans cause global warming, not earthworms. Since earthworms have been around for hundreds of millions of years, it would be naïve to assume they suddenly started to cause global change somewhere in the previous century.
But a rough guess based on our findings is that earthworm-induced emissions cause around one per cent of global warming. This may not seem much at first glance, but these emissions are only marginally less than all fossil fuel used in global air travel.