MSGID: 1:317/3 63d89968   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Monitoring an 'anti-greenhouse' gas: Dimethyl sulfide in Arctic air   
      
      
     Date:   
         January 30, 2023   
     Source:   
         Hokkaido University   
     Summary:   
         Data stored in ice cores dating back 55 years bring new insight   
         into atmospheric levels of a molecule that can significantly affect   
         weather and climate.   
      
      
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   FULL STORY   
   ==========================================================================   
   Data stored in ice cores dating back 55 years bring new insight into   
   atmospheric levels of a molecule that can significantly affect weather   
   and climate.   
      
      
   ==========================================================================   
   Dimethyl sulfide (C2H6S) is a small molecule released by phytoplankton in   
   the ocean, which can play a big role in regulating the Earth's climate. It   
   encourages cloud formation above the sea, and is often called an 'anti-   
   greenhouse gas', since clouds block radiation from the sun and lower   
   sea surface temperatures. At least some blocked heat will be retained   
   in the atmosphere, however, so the effects can be complex. Researchers   
   at Hokkaido University have charted evidence for increasing dimethyl   
   sulfide emissions linked to the retreat of sea ice from Greenland as the   
   planet warms. They report their findings in the journal Communications   
   Earth & Environment.   
      
   Modelling studies have long suggested that the decline in Arctic sea   
   ice could lead to increased dimethyl sulfide emission, but direct   
   evidence for this has been lacking. Assistant Professor Sumito Matoba   
   and colleagues have inferred dimethyl sulfide levels over 55 years by   
   quantifying the related compound, methane sulfonic acid (MSA), in ice   
   core samples from the south-east Greenland ice sheet. MSA is directly   
   produced from dimethyl sulfide, serving as a stable record of dimethyl   
   sulfide levels. This process is part of a variety of chemical interactions   
   among aerosols in the atmosphere.   
      
   The team, including researchers from Nagoya University and Japan's   
   Aerospace Exploration Agency, reconstructed the annual and seasonal MSA   
   flux from 1960 to 2014, at a monthly resolution. The annual MSA levels   
   decreased from 1960 to 2001, but then markedly increased after 2002.   
      
   "We found that July to September MSA fluxes were three to six times higher   
   between 2002 and 2014 than between 1972 and 2001," says Matoba. "We   
   attribute this to the earlier retreat of sea ice in recent years."   
   Supporting evidence comes from satellite data that has monitored the   
   levels of the crucial sunlight-absorbing green pigment chlorophyll-a   
   in the surrounding seas. The chlorophyll-a serves as an indicator of   
   phytoplankton abundance, which in turn should correlate well with the   
   amount of dimethyl sulfide released by the phytoplankton.   
      
   Arctic temperatures are rising twice as fast as the global average,   
   and the summer seasonal sea ice extent has declined sharply in recent   
   decades. This increases the amount of light striking the ocean and   
   promotes the growth of phytoplankton.   
      
   While the latest results from the Hokkaido team add important confirmation   
   of the changing dimethyl sulfide levels, Matoba emphasises that long-term   
   and continuous monitoring of aerosols is needed. "This will be essential   
   to follow the current impact, and predict future impacts, of dimethyl   
   sulfide emissions on the global climate," he says.   
      
       * RELATED_TOPICS   
             o Earth_&_Climate   
                   # Global_Warming # Climate # Oceanography # Ice_Ages   
             o Fossils_&_Ruins   
                   # Early_Climate # Origin_of_Life # Fossils # Ancient_DNA   
       * RELATED_TERMS   
             o Ice_core o Weather o Greenland_ice_sheet o Climate_model   
             o Global_climate_model o Climate o Radiocarbon_dating o   
             Weather_forecasting   
      
   ==========================================================================   
   Story Source: Materials provided by Hokkaido_University. Note: Content   
   may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Yutaka Kurosaki, Sumito Matoba, Yoshinori Iizuka, Koji Fujita, Rigen   
         Shimada. Increased oceanic dimethyl sulfide emissions in areas of   
         sea ice retreat inferred from a Greenland ice core. Communications   
         Earth & Environment, 2022; 3 (1) DOI: 10.1038/s43247-022-00661-w   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/01/230130213938.htm   
      
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