How to improve a negative team atmosphere?

Problem

I was once tasked with taking over quite a large engineering team with sub-teams and I wasn't familiar with the leads of those sub-teams. I progressively noticed that there was an existing culture of negativity, blame, and victim mentalities. This was often even promoted through the ranks by the managers when they became frustrated with problems. This was often an understandable human reaction, but quite a detrimental management mistake, which encouraged dissent.

Actions taken

The culture of negativity, blame and victimization was a very hard issue to address, as it was deeply seeded in the sub-teams' cultures and habits. I believe the only way to even make a dent in this type of problem is to be direct, firm, and clear about what negative effects come from these types of behaviors. For example, when I observed a manager promoting negativity towards other disciplines and groups within the company during a meeting, I asked him to hang back after the meeting. I then explained to him that it's fine for him to identify problems with other groups (and even to be upset about them, we're only human). However, I also explained that his job was to proactively figure out how to resolve these problems, and that he should not sow seeds of discontent within his team. This only made his own job harder.

Lessons learned

Not tolerating the promotion of negativity is really important. From there, it's a matter of being diligent, attentive, and patient. Bad habits take time to reshape, and you must address them directly whenever they show up. Reshaping a team's thinking towards solution-oriented problem solving and encouraging self-agency is critical for a healthy team dynamic long-term.