Dürre und Starkregen

There has been no rain of blogs recently, a drought that I will not compensate for by heavy rainfall. Personal reasons gave me little time for writing, and the circumstances did not encourage me either. But yes, I am back at last.

Droughts and heavy rainfalls are consequences of the climatic change we live through. These two weather phenomena are increasingly observed globally.

Last week, Red Baron listened to two talks in the framework of the Freiburger Umweltgespräche (Freiburg Environmental Talks) organized at the local Jazz House.

In his presentation about climate change and water shortage in Germany's southwest, Dr. Andreas Becker of the German Meteorological Service presented measured "hard" data but refused to paint horror scenarios.

Here is a global map of greenhouse gas emissions, showing the pattern one would expect. The consumption-friendly Western countries and the populous economies of China and India stick out.

Dr. Becker presented the increase in CO₂ concentration in the air from a measuring station at the Mount Loa Observatory in Hawaii, which serves as the world's reference point. Recently, a record "air mark" of 415 ppm was exceeded.

"As recently as 1910, atmospheric CO₂ stood at 300 ppm – higher than it had been for some 800,000 years at least* – but jumped up another 100+ ppm over the next century as pollution levels skyrocketed."
*Measured in drill cores from ice layers

For the future, Dr. Becker presented two scenarios to choose from: If the signatories of the Paris Climate Agreement take active countermeasures against CO₂ emissions, a value of 400 ppm could be capped by 2100. Taking no measures will extrapolate the CO₂ concentration to 1370 ppm in the same year. 

Regarding the total amount of rain in Baden-Württemberg, the region still seems well off.

On a global level, however, observed climatic changes are dramatic. The ice around the North Pole is melting rapidly, as shown by the decrease in the surface covered by ice from 1980 to 2018. The albedo of the white snow reflecting the solar radiation becomes lower, further heating up the sea, and the cold mass of ice diminishes.

At first look, these effects alone may not seem of great concern, but to say it with a quotation from Schiller's drama Wallenstein: The curse of an evil deed is propagating and will bring forth evil. In fact, climatologists recently observed - with the temperature difference and gradient between the Arctic and the equator region becoming smaller - a weakening of the powerful jetstream. This leads to stable and stationary weather conditions around the globe, causing either persistent rain or long periods of heat and drought, precisely the climate Germany's southwest had lived through last year.

Dr. Becker said that 2018 - shown on the slide with a mean temperature of more than 3 degrees too warm and 40% less precipitation than the mean - was still an exceptional year.

Again, while the total amount of rain from April to October shows no decreasing trend, air temperatures increase due to the increasing sunshine duration.

The drought in the region is caused by increased water evaporation at higher temperatures. It is further accentuated by warm and dry southern winds streaming through the Belfort Gap along the Rhine Valley and sweeping the water vapor.

The balance between precipitation and evaporation looks particularly grim for the region around Berlin.

Professor Markus Weiler's talk was somewhat technical and concerned about heavy rainfall and town flooding. I only retained one of his slides showing a persistent local depression, i.e., a rain cell of only 10 kilometers in diameter but stationary for one hour. It had precipitation of around 50 mm, destroying the nearby town of Braunsbach by flooding.

As early as 2008, Red Baron reported on climate change at a Stammtisch of the Freiburg-Madison Gesellschaft. I accentuated the topic further in 2014 and 2015, harping on the Energiewende (energy system transformation).

We cannot escape. Climate change is real!

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