Ice fizzing

For the second year running our pond has looked like this (larger view in extra).  It looks amazing and there were even more bubbles than last year.

However, the internet tells me that this is methane gas and not oxygen (which I'd assumed), and is due to water-dwelling bacteria feeding on decaying organic matter and releasing methane gas.  It also tells me that this is caused because of global warming and is not a good thing for the planet.