Due to climate change, more and more methane is bubbling up from lakes, ponds, rivers and wetlands throughout the world. The release of methane -- a potent greenhouse gas -- leads to a further increase in temperature, thus creating a positive feedback loop (also known as a 'vicious circle'). Story here.
Methane bubbles from the La Brea Tar Pits - Los Angeles. Photo credit - KimonBerlin