iceland_ash_01Just north of here, on the far side of the impenetrable Vatnajokull ice sheet, lava is spewing from a crack in the earth on the flanks of Bardarbunga, one of Iceland’s largest volcanoes. By volcanologists’ standards, it is a peaceful eruption, the lava merely spreading across the landscape as gases bubble out of it. For now, those gases — especially sulfur dioxide, which can cause respiratory and other problems — are the main concern, prompting health advisories in the capital, Reykjavik, 150 miles to the west, and elsewhere around the country. But sometime soon, the top of Bardarbunga, which lies under as much as half a mile of ice, may erupt explosively. That could send plumes of gritty ash into the sky that could shut down air travel across Europe because of the damage the ash can do to jet engines. And it could unleash a torrent of glacial meltwater that could wipe out the only road connecting southern Iceland to the capital. All of that could happen. Then again, it may not. More