Hundreds or even thousands of huge gas bubbles are exploding in northern Siberia, leaving huge craters in the ground and possibly posing a danger to our planet. The bubbles are thought to be caused either by global warming or changes in Earths orbit which causes permafrost beneath the ground to thaw and release methane. Dr. Gideon Henderson said, The last time we saw a permafrost melting was 130,000 years ago. Its a natural phenomenon because of changes in the earths orbit. But what is definitely unprecedented is the rate of warming. The warming that happened 130,000 years ago happened over thousands of years What we see happening now is warming over decades or a century. It could have an important effect on our climate as permafrosts store significant amounts of carbon. Henderson said, When [permafrosts] release carbon, it will accelerate the rate of warming in the future.