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14 | NewScientist | 21 May 2011 GOOD news is rare when it comes to the Greenland ice sheet. Yet a model that accurately mimics the way the ice responds to rising temperatures by slipping and sliding into the sea suggests the resulting rise in sea levels may be smaller than feared. In its 2007 forecasts of sea-level rise, the Intergovernmental Panel on Climate Change famously excluded contributions from the Greenland and Antarctica ice sheets because the physics were too poorly understood and complex to model. As a result, the IPCC’s estimate that seas could rise by between 18 and 59 centimetres by 2100 is almost certainly too low. Using data from the last decade, Stephen Price of the Los Alamos National Laboratory in New Mexico has shown that his modelled ice sheet moves in Thank microbes for our mobility OXYGEN-rich microbial mats may have triggered the evolution of animals that could move around. Animal burrows in 600-million-year-old rocks are a surprise, because oxygen levels in the oceans at the time were too low to support energetic activity. To work out how the animals survived, Murray Gingras of the University of Alberta in Edmonton, Canada, explored low-oxygen lagoons in Venezuela. He found that microbial mats on the lagoon floors contained four times as much oxygen as the lifeless water above – enough to support worms and insect larvae. Gingras says the burrows these animals leave are similar to those found in 600-million-year- old rocks. Because the rocks are also found with fossil microbial mats, that suggests the mats allowed animals to become mobile (Nature Geoscience, DOI: 10.1038/ngeo1142). Chimps hunt monkey prey close to local extinction HUMANS are not the only primates that can overhunt another animal. A new study suggests chimpanzees in Uganda have overhunted red colobus monkeys, causing their local population to fall to one-tenth of what it was just over three decades ago – the first time a non-human primate has been shown to overhunt another. The chimps in the forests of Ngogo, in Uganda’s Kibale National Park, are skilled hunters. They work together to catch their monkey prey – typically the red colobus (Procolobus rufomitratus tephrosceles). Thomas Struhsaker of Duke University in Durham, THOMAS M. BUTYNSKI AND YVONNE A. DE JONG/ARKIVE.ORG IN BRIEF Greenland ice in no hurry to raise seas the same way as the real one does. He has calculated that changes which the ice sheet experienced between 1997 and 2007 will lead to a rise of 0.6 cm. Assuming subsequent decades will be similar, the moving ice sheet will raise sea levels by about 4.5 cm by 2100. That is half of the best previous estimate, calculated by Tad Pfeffer at the University of Colorado at Boulder (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.101731310). North Carolina, and colleagues have been regularly surveying primate populations in Kibale. Those surveys show that there was an 89 per cent decline in the red colobus population between 1975 and 2007. Estimating changes in chimpanzee populations is more difficult because chimps tend to spend time on their own, says Struhsaker. But he says that the number of chimps his team has sighted over the years has risen by 53 per cent, which he says suggests that they were prospering at the increasing expense of their prey (American Journal of Primatology, DOI: 10.1002/ajp.20965). Struhsaker examined other factors that might have caused the red colobus decline, such as disease or competition with other monkey species, but all had a much smaller effect than predation by chimpanzees. “LONELY” planets, hurled into empty space after gravitational tussles with their siblings, may be 50 per cent more common than planets orbiting stars. Most planet searches turn up close-in worlds. But microlensing – in which a planet passes in front of a background star, temporarily magnifying its light – can find more distant ones. In two years of hunting for such signals, Takahiro Sumi of Osaka University in Japan and colleagues found 10 objects of about Jupiter’s mass that did not seem to have host stars. The team says that this and other microlensing studies suggest that more planets may be kicked out of their host systems than stay behind (Nature, DOI: 10.1038/nature10092). Lonely planets vs stellar worlds
