He was Prime Minister of Latvia for ten months in 2004, the first Green politician to lead a country in the history of the world.

Emsis also worked as deputy chairman of the Soviet Latvia's State Nature Protection Committee.

In 1990, he became one of founders of Latvian Green Party (LZP) and served as Minister for the environment in the 1990s, working especially for a clean Baltic Sea.

Emsis was appointed special assignments minister of environment in the ministry of Environmental Protection and Regional Development when Andris Šķēle's government was approved in 1995.

In 1998, Emsis joined the parliamentary group of the Labor Party, Union of Christian Democrats and LZP.

In 1998, Emsis assumed the post of Prime Minister Vilis Krištopans' non-staff advisor on environmental protection issues.

In 2000, LZP congress nominated Emsis as the party's candidate for Riga mayor ahead of municipal elections.

He left office on 2 December 2004, when parliament confirmed Aigars Kalvītis of the People's Party as Prime Minister.