TORONTO -- Ontario Premier Kathleen Wynne shuffled a few members of her cabinet this morning, a move triggered by the departure of her environment minister to the Pembina Institute.

Environment Minister Glen Murray is leaving his cabinet position and will resign his Toronto Centre seat on Sept. 1.

The announcement comes as a surprise, as Murray had previously indicated he would run again in next year's provincial election.

Murray will become the executive director of the Pembina Institute, an environmental think-tank.

Chris Ballard, who had been serving as Ontario's housing minister, moves to the environment portfolio, and Peter Milczyn is promoted to cabinet to take over at housing.

Murray has been a fierce defender of his environmental positions and under his tenure the ministry implemented an ambitious cap-and-trade program aimed at reducing greenhouse gas emissions.

A former mayor of Winnipeg, Murray was first elected to the Ontario legislature in 2007 and served as minister of research and innovation and minister of training, colleges and universities under then-premier Dalton McGuinty.

After Wynne was elected premier, she gave him the portfolios of infrastructure and transportation.

Wynne said in a statement that Murray has always been guided by his passion.

"He is unrelenting in his advocacy for the issues he cares deeply about, dedicated to the people he represents in Toronto Centre and across the province...There is no doubt that Glen's voice, candour and passion at the cabinet table will be missed."

Wynne also cheered Murray's advocacy for the LGBTQ community as the country's first openly gay mayor.

"Glen's career has courageously lead by example, paving the way for people to be their true selves and become whatever they want to be," she wrote.

Murray said in his statement that the decision to leave was a difficult one that he made with the support of his partner, Rick.

"I have also always viewed my life and career as split up into distinct chapters and often in response to serious challenges," he wrote. "When confronted with a choice between the 'unthinkable' and the 'impossible,' I will always take on the impossible to stop the unthinkable."

With the provincial election set for June 7, Wynne said she would not be calling a Toronto Centre byelection because of the cost.