Science  20 Jul 2012:
Vol. 337, Issue 6092, pp. 275

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  1. Fertilized Blooms Deposit Carbon To Deep Sea

    For the first time, scientists have direct evidence that carbon formed from algal blooms fertilized with iron does sink to the deep ocean—a finding that might renew interest in using iron fertilization as a way to sequester carbon dioxide and possibly mitigate climate change.

    Diatom Chaetoceros atlanticus, a type of plankton in the Southern Ocean.


    Iron is a limiting nutrient in many parts of the ocean. Previous studies have shown that adding iron to the upper ocean stimulates blooms of phytoplankton, which in turn take up increased amounts of carbon dioxide from the atmosphere. But it was unclear whether that carbon would then be prevented from interacting with the atmosphere by sequestering it away in the deep ocean.

    As part of the 2004 European Iron Fertilization Experiment, oceanographer Victor Smetacek of the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany, and colleagues tracked particles of phytoplankton biomass in the Southern Ocean as they sank from the surface to the ocean floor. More than half of the carbon captured by the algal bloom during the iron fertilization experiment sank more than 1000 meters, they reported this week in Nature.

  2. Global Warming Punched Up Some 2011 Extremes

    Human-induced global warming is increasing the chances that Texas will be hit with record heat and dryness or that the United Kingdom will have an unusually mild winter—but linking extreme weather to global warming isn't always that simple, note a group of analyses in the July issue of the Bulletin of the American Meteorological Society. For example, the strengthening greenhouse had nothing to do with last year's flooding in Thailand, the new analyses find.

    Rainfall in the catchment basin (red box) of Thailand's Chao Phraya river was not unusual in 2011; flood losses were likely due to floodplain building.


    Researchers under the aegis of the U.S. National Oceanic and Atmospheric Administration and the U.K. Met Office used a variety of techniques to search for any link between the atmosphere's mounting greenhouse gases and extreme weather and climate around the world. Some methods involved climate modeling, while others drew on long climate records for the regions involved.

    The backers of this first prompt analysis of extreme climate and weather events plan to make it an annual “attribution service” to sort out global warming's effects on high-profile events while they are still fresh in the minds of the public and decision makers.