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   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Methane from megafires: More spew than we knew    
    Novel detection technique raises pollution policy questions    
      
     Date:   
         April 17, 2023   
     Source:   
         University of California - Riverside   
     Summary:   
         Using a new detection method, scientists found a massive amount of   
         methane, a super-potent greenhouse gas, coming from wildfires --   
         a source not currently being accounted for by California state   
         air quality managers.   
      
      
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   FULL STORY   
   ==========================================================================   
   Using a new detection method, UC Riverside scientists found a massive   
   amount of methane, a super-potent greenhouse gas, coming from wildfires --   
   a source not currently being accounted for by state air quality managers.   
      
      
   ==========================================================================   
   Methane warms the planet 86 times more powerfully than carbon dioxide   
   over the course of 20 years, and it will be difficult for the state to   
   reach its required cleaner air and climate goals without accounting for   
   this source, the researchers said.   
      
   Wildfires emitting methane is not new. But the amount of methane from   
   the top 20 fires in 2020 was more than seven times the average from   
   wildfires in the previous 19 years, according to the new UCR study.   
      
   "Fires are getting bigger and more intense, and correspondingly,   
   more emissions are coming from them," said UCR environmental sciences   
   professor and study co- author Francesca Hopkins. "The fires in 2020   
   emitted what would have been 14 percent of the state's methane budget   
   if it was being tracked."  The state does not track natural sources of   
   methane, like those that come from wildfires. But for 2020, wildfires   
   would have been the third biggest source of methane in the state.   
      
   "Typically, these sources have been hard to measure, and it's questionable   
   whether they're under our control. But we have to try," Hopkins   
   said. "They're offsetting what we're trying to reduce."  Traditionally,   
   scientists measure emissions by analyzing wildfire air samples obtained   
   via aircraft. This older method is costly and complicated to deploy.   
      
   To measure emissions from 2020's Sequoia Lightning Fire Complex in the   
   Sierra Nevadas, the UCR research team used a remote sensing technique,   
   which is both safer for scientists and likely more accurate since it   
   captures an integrated plume from the fire that includes different   
   burning phases.   
      
   The technique, detailed in the journal Atmospheric Chemistry and Physics,   
   allowed the lead author, UCR environmental sciences Ph.D. student Isis   
   Frausto- Vicencio to safely measure an entire plume of the Sequoia   
   Lightning Fire Complex gas and debris from 40 miles away.   
      
   "The plume, or atmospheric column, is like a mixed signal of the whole   
   fire, capturing the active as well as the smoldering phases," Hopkins   
   said. "That makes these measurements unique."  Rather than using a   
   laser, as some instruments do, this technique uses the sun as a light   
   source. Gases in the plume absorb and then emit the sun's heat energy,   
   allowing insight into the quantity of aerosols as well as carbon and   
   methane that are present.   
      
   Using the remote technique, the researchers found nearly 20 gigagrams of   
   methane emitted by the Sequoia Lightning Fire Complex. One gigagram is   
   1,000 metric tons. An elephant weighs around one metric ton. For context,   
   the fire therefore contained roughly 20,000 elephants' worth of the gas.   
      
   This data matches measurements that came from European space agency   
   satellite data, which took a more sweeping, global view of the burned   
   areas, but are not yet capable of measuring methane in these conditions.   
      
   If included in the California Air Resources Board methane budget,   
   wildfires would be a bigger source than residential and commercial   
   buildings, power generation or transportation, but behind agriculture   
   and industry. While 2020 was exceptional in terms of methane emissions,   
   scientists expect more megafire years going forward with climate change.   
      
   In 2015, the state first established a target of 40 percent reduction in   
   methane, refrigerants and other air pollutants contributing to global   
   warming by 2030. The following year, in 2016, Gov. Jerry Brown signed   
   SB 1383, codifying those reduction targets into law.   
      
   The reductions are meant to come from regulations that capture methane   
   produced from manure on dairy farms, eliminate food waste in landfills,   
   require oil and gas producers to minimize leaks, ban certain gases in   
   new refrigerators and air conditioners, and other measures.   
      
   "California has been way ahead on this issue," Hopkins said. 'We're   
   really hoping the state can limit the methane emissions under our control   
   to reduce short-term global warming and its worst effects, despite the   
   extra emissions coming from these fires."   
       * RELATED_TOPICS   
             o Earth_&_Climate   
                   # Wildfires # Climate # Global_Warming #   
                   Environmental_Issues   
             o Science_&_Society   
                   # Environmental_Policies # Energy_Issues # STEM_Education   
                   # Resource_Shortage   
       * RELATED_TERMS   
             o Greenhouse_gas o Natural_gas o Methane o Air_pollution   
             o Hydrogen_vehicle o Alternative_fuel_vehicle o   
             Sulfur_hexafluoride o Greenhouse_effect   
      
   ==========================================================================   
   Story Source: Materials provided by   
   University_of_California_-_Riverside. Original written by Jules   
   Bernstein. Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Isis Frausto-Vicencio, Sajjan Heerah, Aaron G. Meyer, Harrison   
      A. Parker,   
         Manvendra Dubey, Francesca M. Hopkins. Ground solar absorption   
         observations of total column CO, CO2, CH4, and aerosol   
         optical depth from California's Sequoia Lightning Complex Fire:   
         emission factors and modified combustion efficiency at regional   
         scales. Atmospheric Chemistry and Physics, 2023; 23 (7): 4521 DOI:   
         10.5194/acp-23-4521-2023   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/04/230417142508.htm   
      
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