Cameron's administration reshuffled several key ministerial positions Tuesday.
The prime minister sacked Owen Paterson as secretary of state for the environment, food and rural affairs. Paterson was criticized for his controversial stance on climate issues.
"David Cameron is right to give Owen Paterson the boot -- he's the worst Environment Secretary the U.K. has had for decades," Friends of the Earth Executive Director Andy Atkins said in a statement.
Friends of the Earth said Paterson had "willfully ignored" evidence of climate change. Paterson was replaced by Liz Truss.
"We hope she will mark a clean break with Owen Paterson by listening to science and striving for evidence-based decision making," Atkins said.
William Hague's decision to stand down as foreign minister was among the more high-profile re-appointments.
Minister of Energy and Climate Change Greg Barker resigned and was replaced by Matthew Hancock.