The best I can figure out there has been a massive increase in global methane levels in the last millenia or so. I suppose we could argue about the source but

The best I can figure out there has been a massive increase in global methane levels in the last millenia or so. I suppose we could argue about the source but livestock is the most obvious candidate. Edit: Okay turns out fossil fuels are also responsible fro some non-negligible part of the methane emissions, and it's not just livestock but all agriculture and the resulting waste.