Research by Russian and German scientists has shown that warmer sea surface temperatures can lead to an increase in precipitation intensity – in some cases of over 300% – for communities and regions neighbouring warm seas.
The study reveals a connection between warming seas and major flood events in the Black Sea region, such as Krymsk in 2012, or more recently Sochi in June this year.
The Black Sea and eastern Mediterranean have warmed by about 2 degrees Celsius since the early 1980s. Russian and German scientists at the Helmholtz Centre for Ocean Research Kiel (GEOMAR) investigated what impact this warming may have had on extreme precipitation in the region.
They now believe that in coastal regions neighbouring warm seas, the sea surface temperature can play a crucial role in the intensity of convective storms.
“Our showcase example was a heavy precipitation event from July 2012 that took place in Krymsk (Russia), near the Black Sea coast, resulting in a catastrophic flash food with 172 deaths”, said Edmund Meredith, lead author of the study.
“We carried out a number of very-high-resolution simulations with an atmospheric model to investigate the impact of rising sea surface temperatures on the formation of intense convective storms, which are often associated with extreme rainfall”, Meredith continued.
Simulations of the event with observed sea surface temperatures showed an increase in precipitation intensity of over 300%, compared to comparable simulations using sea surface temperatures representative of the early 1980s. “We were able to identify a very distinct change, which demonstrates that convective precipitation responds with a strong, non-linear signal to the temperature forcing”, Prof. Douglas Maraun, co-author of the study said.
At the end of June 2015, the nearby Olympic city of Sochi experienced an unusually intense precipitation event. Over 175 mm of rain was recorded in 12 hours, showing the relevance of the scientists’ work.
Prof. Douglas Maraun added:
“Due to ocean warming, the lower atmosphere has become more unstable over the Black Sea and eastern Mediterranean. We therefore expect that events like those in Krymsk or Sochi will become more frequent in the future”
Simulated Precipitation for Two Different SST Cases