A total of 300 people are behind the lawsuit.
It's about them wanting a court to rule that the state has an obligation to take certain specified actions to mitigate climate change.
"It's really exciting, of course. It feels like our hard work has paid off, says Agnes Hjortsberg, press contact for the youth movement Aurora.
According to Alderman Olof Roos, who is responsible for the case, it stands out.
"I'm not aware that there has been any action like this against that state before. There are some examples internationally I have learned, but not in Sweden, says Olof Roos.
The state now has three months to respond to the lawsuit.
Hear the climate activists' reasoning ahead of the lawsuit last year:
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Hear the climate activists about why they want to sue the state - and environmental law professor Jonas Ebbesson who is skeptical of the move. Photo: SVT