Geological Society of America Meets in Denver: Paleocene-Eocene Thermal Warming and Comparisons to Today's Global Warming

      An era of skyrocketing global temperatures started with an impact bang according to research presented September 27, 2016, here in Denver at the Geological Society of America's Annual Meeting.

         Impact debris and evidence of widespread wildfires in eastern North America suggest that a large space rock hit earth around 56 million years ago at the beginning of the Paleocene-Eocene Thermal Maximum, also known as the PETM, a period of rapid warming and huge increases in carbon dioxide.

     The event is one of the closest historic analogs to modern global warming and is used to improve predictions of how earth’s climate and ecosystems will fare in the coming decades.

     Too little is known about the newfound impact to guess its origin, size or effect on the global climate, said Dr. Morgan Schaller of Rensselaer Polytechnic Institute. But it fits in with the long-standing and controversial proposal that a comet impact caused the PETM. “The timing is nothing short of remarkable,” said Schaller at the GSA meeting.

     The impact may have contributed to the rapid rise in CO2 by stirring carbon up into the atmosphere, but it was hardly the sole cause, said Sandra Kirtland Turner, a geochemist at the University of California, Riverside. Her own environmental simulations suggest that the influx of carbon that flooded Earth during the PETM probably took place over at least 2500 years, far too drawn out to be caused by a single event, she said at the same meeting.

     During the PETM, a massive influx of carbon flooded the atmosphere and earth warmed by 5 to 8 degrees Celsius to temperatures much hotter than today. That carbon dump altered the relative abundance of different carbon isotopes in the atmosphere and oceans, leaving a signal in the sedimentary record.

     While searching for that signal in roughly 56-million-year-old sediments from sites up and down the U.S. east coast, Schaller spotted microscopic glassy spheres about the size of a dust mite as seen in SEM:

      These specks resemble those blasted from previously identified large impact events.

     After switching from a black to a white sorting tray to more easily see the black debris, researchers discovered abundant charcoal pieces in the mix, as seen below in a Scanning Electron Microscope (SEM) image. That charcoal likely formed when wildfires sparked by the impact raged across the landscape.

     More evidence of the impact will help researchers to better constrain its location, scope and possible relationship to the start of the PETM, Dr. Schaller said.

Have you ever made a simple change a la "black tray to white tray switch" to discover something new?
Steph

WE ARE CELEBRATING THREE YEARS OF PARTIAL ELLIPSIS OF THE SUN. . .

Calving: Ice or Cow. . .And Is There A Connection?

          For this week's PEOTS, how about choosing between ice calving

      or cow (or moose or seal or whale) calving?

      Hmmmm. Let's go with ice calving. Check out this largest filmed ice calving event at the Ilulissat Glacier in Greenland. 

      Ice calving, also known as glacier calving or iceberg calving, is the breaking off of chunks of ice at the edge of a glacier, iceberg, ice shelf, or crevasse. The ice that breaks away is classified as an iceberg, but may also be called a growler or bergy bit.

     Growlers are smaller pieces of ice, generally rising less than a meter above water level, that make a growling animal sound as they move in the ocean. Bergy bits are mini icebergs that rise up to 4-5 meters above the water level. 

        

         Ice calving has gotten lots of attention lately as a result of global warming (See the 2014 documentary Ice Chasing).

        And perhaps watch it with this kind of beer growler:

       Do you suppose there's any connection between the sound of cows birthing and the sound of ice calving (the latter term first originated in Denmark in 1837), growlers and all?

Enjoy that ice calving blue; looking forward to your insights,

Steph