Earth/Environment

A big bang
Geologists have uncovered the remains of one of the biggest volcanic eruptions ever. Some 21 million years ago, a volcano blew its top in southern Java with as much violence as the Toba supereruption of 74,000 years ago — until now, the gold standard by which big eruptions have been measured. Remains of the ancient eruption linger as massive volcanic rocks across Indonesia, report Helen Smyth of the University of Cambridge in England and her colleagues. The volcano, dubbed Semilir, may have changed the world’s climate, the scientists report in an upcoming issue of Lithos. — Alexandra Witze

Arctic ice in the balance
A new analysis of polar sea-ice records going back 10 millennia shows that when ice cover greatly diminished in one area in the Arctic, there were somewhat compensating increases elsewhere. This challenges what had been the prevailing view: that ice accumulation — or thinning — had been a fairly uniform phenomenon through the region, a European team reports in the Aug. 5 Science. One part of the analysis looked at how long it took driftwood to reach Greenland’s shorelines after a torturous trip through ice from distant sites in Asia or North America.—Janet Raloff

Ozone as food cleanser
Fumigating fresh produce with ozone can remove a large share of fungicide residues present on the surface. Although chemical treatments can protect fruits and veggies from insects, fungi and more, consumers want those pesticides gone by the time foods reach the lunch box or dinner table. An international team of researchers has now demonstrated ozone fumigation of Thompson seedless grapes. Although ozone had no effect on several fungicides, it removed 35 to 64 percent of three commonly used types: fenhexamid, cyprodinil and pyrimethanil. The scientists describe this first use of ozone as a pesticide eraser online July 26 in Environmental Science & Technology. —Janet Raloff

Beetle evolves resistance to Bt
One of agriculture’s most devastating pests, the western corn rootworm, has evolved resistance to corn genetically engineered to make a poison derived from the Bacillus thuringiensis — or Bt — bacterium. Bt’s lethality to many pests has made genetic engineering of its toxin into crops a primary pest-control strategy. The July 29 report in PLoS ONE by scientists at Iowa State University in Ames is the first confirmation of any beetle or weevil’s ability to survive on corn making Bt toxin (although some butterflies or moths are resistant).  The Iowa State team attributes the rootworm resistance to too few Bt-free corn refuges that allow sensitive insects to flourish. —Janet Raloff

No deep freeze for pollutants
Pollutants once frozen in the Arctic are re-entering the environment thanks to climate change. Many persistent organic pollutants, a group of chemicals from industrial and other sources, have traveled northward and been trapped in Arctic ice. Scientists recently measured pollutant levels in Svalbard and northern Canada, finding that a wide range had made it into the air since the early 1990s. The chemicals are probably making their way out of melting ice and back into atmospheric circulation, a team led by Jianmin Ma of Environment Canada in Toronto suggests online July 24 in Nature Climate Change. —Alexandra Witze

Yellowstone wildfire risk
Bison, wolves, tourists and other creatures roaming Yellowstone should prepare themselves for greater chances of wildfires like those that struck the park in 1988. Anthony Westerling of the University of California, Merced and his colleagues examined Yellowstone’s fire history and calculated its future under various climate scenarios using three computer models. All projected a more fiery future; for example, by mid-century fires could burn through the equivalent of the park’s entire area every 30 years. Before 1990, fires took an average of more than 120 years to do so, the team reports in the Proceedings of the National Academy of Sciences July 25. —Alexandra Witze