After Greenpeace activists absconded with the "C", they unfurled a banner next to the remaining letters that translated to: "You should protect the climate." The move came just ahead of the CDU's annual party conference.
Videos of the protest showed an activist walking away from the CDU headquarters with the big red C strapped to their back. That left only the letters "DU" remaining on display — which is the German word for "you."
Other Greenpeace members appeared and rappelled from the roof to unfurl a banner next to the DU which translated to: "You should protect the climate."
Shortly after the C disappeared, an account called "I am the C" appeared on Twitter — documenting the C's travels through the German capital and calling out Merkel's party for its failings.
"Hello World! I am the C of the CDU and I've had enough! I can't be with [you] any longer. Protecting creation means protecting the climate," read one post, referencing one of the conservative party's campaign slogans.
It was unclear what the activists planned on doing with the C, but they vowed that the red letter was "going on a trip."
'We're happy to lend it to them'
CDU leader and German Defense Minister, Annegret Kramp-Karrenbauer, appeared to take the protest, which took place shortly before the start of the CDU'S annual party conference in Leipzig, in her stride.
"It wouldn't hurt Greenpeace to have a 'C' [that stands for] for Christianity and sustainability — we're happy to lend it to them for a short time," she said, according to news agency DPA.
CDU secretary general Paul Ziemiak posted a picture of himself from the party conference posing with another, older copy of the party's logo.
"We're in luck since the original 'C' is here in Leipzig," he wrote.
The party, or supporters of the party, countered the Greenpeace protest by creating the rival account "I am the DU" on Twitter. One of the posts, which said it was a "love letter to the C," included a link to the CDU membership page.
Greenpeace said it planned the logo letter theft to protest against the CDU's "disastrous climate policies."
Although the plan, which was hammered out by Merkel's coalition government, seeks to cut greenhouse gas emissions to 55% of the 1990 levels by 2030. Germany is lagging behind its current goals, having only achieved 30% of the target it hopes to achieve by 2030.
From temperature increases to predictions of sea level rise, Germany's seas and coastal communities are facing changes that require pre-emptive action.
Image: picture-alliance/dpa/H. Marschall
Keeping the coast safe
At the moment, water levels in Germany's North and Baltic Seas are not rising any faster than usual, but scientists say the process is likely to speed up in the coming decades. Exactly when, and by how much, is uncertain. And that complicates the work of coastal defense authorities.
Image: picture-alliance/dpa/I. Wagner
Feat of engineering
Over the centuries, the hundreds of kilometers of dikes along Germany's coastline have become higher and more sophisticated. The latest incarnations are called "climate dikes" and are especially designed to be able to hold back higher waters brought about by warming temperatures and rising sea levels.
Image: DW/Tamsin Walker
Houses on tiny hills
One time-honored way populations under threat from higher sea levels have sought to secure themselves, has been to build their homes on small mounds. On the so-called Hallig islands, it is not uncommon for these embankments to be all that is left above water during a storm surge.
Image: WWF/H.-U. Rösner
Cod off to cooler waters
Unlike sea-level rise, an increase in temperatures in Germany's North and Baltic Seas is already palpable. Scientists say both bodies of water are around 1 degree Celsius (1.8 degrees Fahrenheit) warmer than in the 1960s. This shift in conditions has had an impact on several species, including cod, which have begun to migrate north in search of the cold in which they thrive.
Image: by-nc-sa/Joachim S. Müller
Heading for the heat
At the other end of the scale, anchovies are increasingly making a home for themselves in the North Sea off Germany. The species is usually found in more southerly climes, but the warming temperatures are attracting them to new waters.
Image: Imago/blickwinkel
Mud flats in danger
The Wadden Sea UNESCO World Heritage Site is also at risk from the predicted sea-level rise. It serves as a resting place for millions of migratory birds traveling between the Arctic and warmer regions to the south. Because it is so rich in food, the birds stop there for several weeks at a time to build up fat and energy reserves for their onward journeys.
Image: WWF/H.-U. Rösner
Life in the salt marsh
While few plant species can survive the salty waters that regularly flood the marshes between the Wadden Sea and the dikes, the environment is alive with tiny insect species and birds that nest at ground level.
Image: DW/Tamsin Walker
Drowning dinner
If the sea level were to rise too quickly, the Wadden Sea's characteristic mud flats would no longer be exposed at low tide. That would have huge implications, not only for the birds that rely on the ecosystem for food, but for the ecosystem itself.
