Weibo is a Chinese microblogging service, similar to Twitter. The service, like Twitter and Facebook, has been integrated into iOS and OS X for the past few years. Tim Cook's account, which is verified by the service, has only one post, announcing Apple's new environmental initiatives in China during a stop in Beijing.

From Tim Cook on Weibo:

Hello China! Happy to be back in Beijing, announcing innovative new environmental programs.

As of this writing the account has 327,821 followers since its creation earlier today. By comparison, Cook has almost 1.2 million followers on Twitter since creating the account in July 2013.

China has become a very important market for Apple. The company sold a record number of phones in the country in early 2015, capturing more than a quarter of the Chinese smartphone market to become the top smartphone vendor in the country.

Source: Tim Cook (Weibo)