(July 13, 2015) Recent
event underlines importance of study by German and Russian scientists
Due to climate change, not only atmospheric, but also
oceanic, temperatures are rising. A study published in the international
journal Nature Geoscience led by scientists at the GEOMAR Helmholtz Centre for
Ocean Research Kiel shows that increases in sea surface temperature can contribute
to the development of stronger precipitation events. Their findings are
underpinned by flash-flooding in June in the Olympic city of Sochi, Russia.
That the temperatures on our planet are rising is clear. In
particular, the increasing emissions of greenhouse gases such as carbon dioxide
continue to warm the atmosphere. The effects of global warming on the
hydrological cycle, however, are still not fully understood. Particularly
uncertain is how the strength of extreme summertime thunderstorms have changed,
and how it may change in the future. In coastal regions neighboring warm seas,
the sea surface temperature can play a crucial role in the intensity of
convective storms. The Black Sea and eastern Mediterranean have warmed by about
2 C since the early 1980s. Russian and German scientists investigated what
impact this warming may have had on extreme precipitation in the region.
“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 added.