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   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Massive iceberg discharges during the last ice age had no impact on   
   nearby Greenland, raising new questions about climate dynamics    
      
     Date:   
         April 24, 2023   
     Source:   
         Oregon State University   
     Summary:   
         New findings suggest that Heinrich Events had no discernible impact   
         on temperatures in Greenland, which could have repercussions for   
         scientists' understanding of past climate dynamics.   
      
      
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   FULL STORY   
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   During the last ice age, massive icebergs periodically broke off from   
   an ice sheet covering a large swath of North America and discharged   
   rapidly melting ice into the North Atlantic Ocean around Greenland,   
   triggering abrupt climate change impacts across the globe.   
      
   These sudden episodes, called Heinrich Events, occurred between 16,000   
   and 60,000 years ago. They altered the circulation of the world's oceans,   
   spurring cooling in the North Atlantic and impacting monsoon rainfall   
   around the world.   
      
   But little was known about the events' effect on nearby Greenland, which   
   is thought to be very sensitive to events in the North Atlantic. A new   
   study from Oregon State University researchers, just published in the   
   journal Nature, provides a definitive answer.   
      
   "It turns out, nothing happened in Greenland. The temperature just stayed   
   the same," said the study's lead author, Kaden Martin, a fourth-year   
   doctoral candidate in OSU's College of Earth, Ocean, and Atmospheric   
   Sciences. "They had front-row seats to this action but didn't see   
   the show."  Instead, the researchers found that these Heinrich events   
   caused rapid warming in Antarctica, at the other end of the globe.   
      
   The researchers anticipated Greenland, in close proximity to the ice   
   sheet, would have experienced some kind of cooling. To find that these   
   Heinrich Events had no discernible impact on temperatures in Greenland is   
   surprising and could have repercussions for scientists' understanding of   
   past climate dynamics, said study co-author Christo Buizert, an assistant   
   professor in the College of Earth, Ocean, and Atmospheric Sciences.   
      
   "If anything, our findings raise more questions than answers," said   
   Buizert, a climate change specialist who uses ice cores from Greenland   
   and Antarctica to reconstruct and understand the Earth's climate   
   history. "This really changes how we look at these massive events in   
   the North Atlantic. It's puzzling that far-flung Antarctica responds   
   more strongly than nearby Greenland."  Scientists drill and preserve   
   ice cores to study past climate history through analysis of the dust   
   and tiny air bubbles that have been trapped in the ice over time. Ice   
   cores from Greenland and Antarctica provide important records of Earth's   
   atmospheric changes over hundreds of thousands of years.   
      
   Records from ice cores from those regions have served as pillars for   
   scientists' understanding of past climate events, with ice collected   
   from both locations often telling similar stories, Martin said.   
      
   The impact of Heinrich Events on Greenland and Antarctica was not well   
   understood, spurring Martin and Buizert to try to find out more about   
   what was happening in those parts of the world.   
      
   The core used for the latest study was collected in 1992 from the highest   
   point of Greenland, where the ice sheet is around 2 miles thick. Since   
   then, the core has been in storage in the National Science Foundation   
   Ice Core Facility in Denver.   
      
   Advancement in scientific tools and measurements over the last few decades   
   gave Martin, Buizert and their colleagues the opportunity to re-examine   
   the core using new methods.   
      
   The analysis shows that no changes in temperatures occurred in Greenland   
   during Heinrich Events. But it also provides a very clear connection   
   between Heinrich Events and the Antarctic response.   
      
   "When these big iceberg discharges happen in the Arctic, we now know   
   that Antarctica responds right away," Buizert said. "What happens in   
   one part of the world has an effect on the rest of the world. This   
   inter-hemispheric connection is likely caused by change in global wind   
   patterns."  The finding challenges the current understanding of global   
   climate dynamics during these massive events and raises new questions   
   for researchers, Buizert said. The researchers' next step is to take the   
   new information and run it through climate models to see if the models   
   can replicate what occurred.   
      
   "There has to be a story that fits all of the evidence, something that   
   connects all the dots," he said. "Our discovery adds two new dots; it's   
   not the full story, and it may not be the main story. It is possible that   
   the Pacific Ocean plays an important role that we haven't figured out   
   yet."  The ultimate goal is to better understand how the climate system   
   is connected and how the components all interact, the researchers said.   
      
   "While Heinrich Events are not going to happen in the future, abrupt   
   changes in the globally interconnected climate system will happen again,"   
   Martin said.   
      
   "Understanding the global dynamics of the climate system can help us   
   better project future impacts and inform how we respond and adapt."   
   Additional co-authors are Ed Brook, Jon Edwards, Michael Kalk and Ben   
   Riddell- Young of OSU; Ross Beaudette and Jeffrey Severinghaus of the   
   Scripps Institution of Oceanography; and Todd Sowers of Pennsylvania   
   State University.   
      
   The research was supported by the National Science Foundation, the   
   Global Climate Change Foundation and the Gary Comer Science and Education   
   Foundation.   
      
       * RELATED_TOPICS   
             o Earth_&_Climate   
                   # Climate # Global_Warming # Ice_Ages #   
                   Environmental_Awareness   
             o Fossils_&_Ruins   
                   # Early_Climate # Ancient_DNA # Evolution # Fossils   
       * RELATED_TERMS   
             o Temperature_record_of_the_past_1000_years o   
             Attribution_of_recent_climate_change o Greenland_ice_sheet   
             o Ice_sheet o Annual_sedimentary_layer o Global_warming o   
             Chicxulub_Crater o Climate_model   
      
   ==========================================================================   
   Story Source: Materials provided by Oregon_State_University. Original   
   written by Michelle Klampe. Note: Content may be edited for style   
   and length.   
      
      
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   Journal Reference:   
      1. Kaden C. Martin, Christo Buizert, Jon S. Edwards, Michael L. Kalk,   
      Ben   
         Riddell-Young, Edward J. Brook, Ross Beaudette, Jeffrey   
         P. Severinghaus, Todd A. Sowers. Bipolar impact and phasing   
         of Heinrich-type climate variability. Nature, 2023; DOI:   
         10.1038/s41586-023-05875-2   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/04/230424133551.htm   
      
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