San Francisco Chronicle: Ice in the ocean surrounding the Arctic is thinner than it’s been in 30 years, and there’s much less of it, say scientists who are monitoring the effects of climate change. At the same time, another team of climate scientists is predicting from earlier data that the Arctic’s ice cover has been melting so rapidly over the past few years that much of it could be gone within another three decades. “Ice extent is an important measure of the health of the Arctic,” said Walter Fowler …