Methane levels increase worldwide simultaneously?

Supposedly methane is one of the greenhouse gasses. According to this article, it increased worldwide simultaneously for an unknown reason last year. It's just more evidence that global warming may not be caused by man.

From the article:

One thing does seem very clear, however; science is only beginning to get a handle on the big picture of global warming. Findings like these tell us it's too early to know for sure if man's impact is affecting things at the political cry of "alarming rates." We may simply be going through another natural cycle of warmer and colder times - one that's been observed through a scientific analysis of the Earth to be naturally occuring for hundreds of thousands of years.