held a number of positions in local politics. In 1990, he was first elected to the State Parliament of Lower Saxony, where he led the SPD parliamentary group from 1998 until 1999. Minister-President of Lower Saxony, 1999–2003 On 15 December 1999, after the resignation of Gerhard Glogowski, who had succeeded Gerhard Schröder in office, Gabriel became Minister-President of Lower Saxony. He had previously won an internal party vote against Wolfgang Jüttner and Thomas Oppermann. He served until 4 March 2003. During these years, he was widely presented as a protégé of Schröder, and even as a possible successor as chancellor. After being voted out of office in 2003, Gabriel became the SPD's "Representative for Pop Culture and Pop Discourse" from 2003 to 2005, for which he was bestowed the nickname Siggi Pop. Federal Minister for the Environment, Nature Conservation and Nuclear Safety, 2005–2009 He was elected in Salzgitter – Wolfenbüttel in the 2005 federal election. From 2005 to 2009 Gabriel was the Federal Minister for the Environment, Nature Conservation and Nuclear Safety in the first cabinet of Angela Merkel (CDU). During his time in office, Gabriel promoted the International Renewable Energy Agency. He also led the German delegation to the 2006 United Nations Climate Change Conference in Nairobi. In 2007, when Germany held the presidency of the Council of the European Union, he led the negotiations between European Union environment ministers on an ambitious effort to cut greenhouse gas emissions to 20 percent below 1990 levels. That same year, he accompanied Merkel on a two-day visit to Greenland to see the Ilulissat Icefjord, a UNESCO world heritage site, and the Sermeq Kujalleq glacier in order to get a firsthand look at the effects of global warming. Opposition leader, 2009–2013 Following the SPD's defeat in the federal election of 2009, Franz Müntefering resigned from the position of party chairman of the Social Democratic Party. Gabriel was nominated as his successor and was elected on 13 November 2009. He was re-elected as party chairman for a further two years at the SPD party conference in Berlin on 5 December 2011, receiving 91.6 percent of the vote. During his early years as chairman, Gabriel pushed through internal party reforms. He abolished the party steering committee in favor of an expanded executive committee and led the regular party conventions, the most important meetings for the party. He also played a critical role in founding