Tremors before volcanic eruptions explained, plus more in this week’s news

Thawing world
Rising temperatures will release significant amounts of carbon into the atmosphere from thawing permafrost, according to one of the first studies to quantify how much that carbon will contribute to global warming. A combination of global climate simulations suggests that frozen Arctic lands will go from being a net absorber to a net emitter of carbon sometime next decade, researchers from Boulder, Colo., report online February 15 in Tellus. They project that by 2200 Arctic permafrost extent could shrink by about 30 to 60 percent. —Alexandra Witze

Pulse of an eruption
Volcanologists have explained the puzzling seismic “tremor” that often precedes or accompanies volcanic eruptions. The signal, researchers say, comes from a column of magma rising through the crust surrounded by a ring of gas bubbles. The bubbles bounce off of and corral the magma, causing the rising column to oscillate back and forth. That oscillation matches the frequency of tremor signals seen at many eruptions, scientists from the University of British Columbia in Vancouver and from Yale University report in the Feb. 24 Nature. The work could help in forecasting eruptions. —Alexandra Witze

Global change extends hay fever season
Here’s something to sneeze at. The planet’s slowly rising air temperatures over the past 15 years have extended the period that ragweed sheds its allergy-provoking pollen. In the northern United States and Canada this can lengthen hay fever season some two to four weeks, according to a team of U.S. scientists. Later fall frosts and briefer winters have played a big role in extending the seasonal need for antihistamines and tissues, the researchers conclude in a paper posted online February 21 in the Proceedings of the National Academy of Sciences. —Janet Raloff

Spinning slowly
Earth’s inner core rotates faster than the rest of the planet, but more slowly than scientists had thought. Earlier studies proposed that the inner core, made mostly of solid iron, spins up to 1 degree faster per year than the fluid outer core. Geoscientists have now studied seismic waves bouncing off the inner core to show that it rotates more like 1 degree faster per million years. The finding resolves several puzzles about Earth’s deep interior, such as how the core’s hemispheres have managed to retain distinct physical identities, scientists at the University of Cambridge in England report online February 20 in Nature Geoscience. —Alexandra Witze

Drugged fish
Very low levels of certain widely prescribed anti-inflammatory drugs raise blood sugar and lower white-blood-cell counts in fish — at least in the lab, a new study finds. Wild fish might develop similar problems, say researchers at Brunel University in England, because the same glucocorticoids have been detected in surface waters. The likely source: human sewage or runoff from landfills of drugs discarded as trash. Effects of different glucocorticoids would probably be additive, the authors note. That suggests concentrations in some rivers might be high enough to affect fish, the researchers say in a report posted online February 15 in Environmental Science & Technology. —Janet Raloff

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