Friday Headlines, September 13, 2019
THE LATEST IN THE GEOSCIENCES
This week in geology
- The lost continent below Europe
This week in the environment
- How high can sea level rise?
Europe is marked by contorted mountain ranges, related to the subduction of the African tectonic plate below the European Plate. As one plate slides beneath the other, parts of its surface are scraped off and pressed into the mountain ranges of the overriding plate.
van Hinsbergen et al. (2019) examined the rocks of the mountain ranges of Europe. They focused on assigning ages to the rocks and determining which way was North, in the perspective of the rocks. As rocks are folded, distorted, and twisted into mountains the direction of North preserved in the rock is often turned away from modern North.
The authors then took all the rocks and bent them back so that the North of the rocks pointed to modern North. In doing so, they stretched out the continent to see what was originally there the African Plate began to move under Europe.
What they found was evidence for a small landmass, which they call Greater Adria, which was completely subducted under Europe. This continent would have been observable 140 million years ago, but is now completely gone, except for the traces left in the mountains of Europe.
The Pliocene was a period of time during which temperatures were warmer than today, perhaps as much as 4°C warmer than the pre-industrial Earth. The Pliocene climate, therefore, is thought to be similar to was Earth’s climate will be like in the year 2100, should the trend in global temperature increase continue. Because of this, study of Pliocene rocks can provide a window into where the Earth is going.
Dumitru et al. (2019) examined markers in ancient caves that lie near modern sea level, and that would be inundated by water with higher sea levels, to check where sea level was during the warm times of the Pliocene. They found that global mean sea level (GMSL) was around 16.2 meters higher than modern sea level during much of the warm Pliocene, and was possibly 23.5 meters above modern sea level during the warmest parts of the Pliocene.
The implication is that it’s possible for 10’s of meters of sea level rise to occur with modern global warming. That’s a little scary.