Europe's Rhine River has fallen to record low levels in parts of Germany and the Netherlands, impacting barge freight and disrupting one of the bloc's busiest inland shipping routes.

According to BBC News, water levels measured in Western Germany in Cologne and Lobith have reached their lowest point on record. Levels on July 31 at the Rhine's Kaub station near the city of Koblenz also matched 2018's record low, before rising slightly on August 3.

Kaub — the Rhine's shallowest point — acts as a crucial indicator for the waterway's navigability, since its gauging station is responsible for measuring how heavily cargo vessels can be loaded at any point along the river. That means that any time levels fall at Kaub station, the impacts are felt across the entire Rhine, driving up transportation costs and forcing vessel operators to make difficult choices as to whether a load is too small to be worth shipping. To wit, Bloomberg reports that the cost of shipping diesel along the Rhine from Rotterdam, Netherlands, to Karlsruhe, Germany, has reached its highest point since records began in 2009.

Read More: Record Heat Wave Threatens Crops Across Europe

Meanwhile, levels along the Danube River in Serbia, Romania, Hungary and several other countries also fell to their lowest levels in three decades on July 30, The Guardian reports. For the first time ever, Hungary and Romania also had to shut down nuclear reactors that rely on the Danube for cooling, with the former declaring a nationwide state of emergency for energy production. In response, Romanian naval forces carried out a controlled explosion on August 3 to redirect the Danube's waters to the country's last working nuclear reactor. 

This comes after Western Europe experienced its hottest ever June on record, driven by the highest ever sea surface temperatures on record for the month. Although those conditions are partially the result of a powerful Super El Niño season that took hold on June 11, the World Meteorological Organization points to climate change as a significant factor as well. 

“Heatwaves like this are what we expect to see in a changing climate,” said WMO head of climate information John Kennedy in a July 9 blog post. “In the 50 years since the historic heatwave in 1976, Europe as a whole has warmed by around two degrees."