On his first day as new chief executive, Daimler boss Ola Kallenius prepared his workforce for the trying times ahead as the automaker transitions to a greener business.

Kallenius posted a brief internal audio message via social media on Thursday, in which he called on employees to support a new strategy to fully decarbonize its core automobile fleet over the next 20 years.

"With 'Ambition2039' we want to make our business more sustainable and simultaneously ensure that it still remains a profitable one," he said. "We need to change ... that won't be easy."

Unlike the turbulent transition in 2005, in which Daimler itself called Juergen Schrempp's resignation "unexpected," Dieter Zetsche plotted a smoother course for his successor. In a move signaling continuity, Kallenius was already permitted to announce his 'Ambition2039' plan to the press more than a week before he officially began his five-year term.

It foresees every second Mercedes-Benz sold by 2030 being either a plug-in hybrid or full-electric vehicle as part of a plan to make the fleet carbon neutral another nine years later. In order to ensure management would follow through, he is linking their compensation package to the achievement of these CO2 goals.

Kallenius, who is also CEO of Mercedes-Benz Cars, has not yet disclosed any explicit targets for Mercedes-Benz Vans or Daimler Trucks, the heavy commercial vehicles division, as part of the strategy.

In his audio message, the Swedish national -- the first ever non-native German to run the world's oldest automaker -- said he was excited to begin with his duties. "I have been at Daimler for more than 26 years and yet it still feels a bit like it's my first day again," he said.