Researchers studying a rapid global warming event, around 56 million years ago, have shown evidence of major changes in the intensity of rainfall and flood events. The findings indicate some of the likely implications should current trends of rising carbon dioxide and global warming continue. It follows much discussion on the nature of global change in a warmer 21st Century at the COP23 Climate Negotiations in Bonn last week. The new research, submitted to Climate of the Past Discussions, led by a team at the University of Birmingham, and involving multiple UK institutions and the British Geological Survey, sought to address this question using records from a major warming event in the Earth's past. The rapid global warming event, ~56 million years ago, known as the "Paleocene Eocene Thermal Maximum" or PETM has provided such insights. The team developed detailed records of the PETM event from a sequence of marine sedimentary rocks, now exposed on the coast of the Basque country of northwest Spain.
Before, during and after the PETM, these sediments were laid down on the sea floor at the edge of the Atlantic Ocean, at depths of ~1000m, on the boundary between the continents and the open ocean. The sediments are made up of microscopic calcium carbonate shells and fine-grained clay and silt sediment that is washed in from the nearby European continent. Remarkably, the new records show that the sediment delivery from land to this deep ocean location increased four-fold during the PETM event. The team associate this with major changes in the patterns of rainfall on land, with warming causing more extreme rainfall events, with floods and the associated erosion and transport of sediments into the oceans. Read more....
No comments:
Post a Comment