evidence: Dear EarthTalk: Could it really be true that a single large volcanic eruption launches more greenhouse gases into the atmosphere than the amount generated by all of humanity over history? --Steve Schlemmer, London, England [...] Another indication that human emissions dwarf those of volcanoes is the fact that atmospheric CO2 levels, as measured by sampling stations around the world set up by the federally funded Carbon Dioxide Information Analysis Center, have gone up consistently year after year regardless of whether or not there have been major volcanic eruptions in specific years. "If it were true that individual volcanic eruptions dominated human emissions and were causing the rise in carbon dioxide concentrations, then these carbon dioxide records would be full of spikes—one for each eruption," says Coby Beck, a journalist writing for online environmental news portal Grist.org. "Instead, such records show a smooth and regular trend."