NEW YORK—In a major shift, a group of Southern Baptist leaders said their denomination has been “too timid” on environmental issues and has a biblical duty to stop global warming.

The declaration, signed by the president of the Southern Baptist Convention among others and released Monday, shows a growing urgency about climate change even within groups that once dismissed claims of an overheating planet as a liberal ruse. The conservative denomination has 16.3 million members and is the largest Protestant group in the U.S.

The signers of “A Southern Baptist Declaration on the Envi-ronment and Climate Change” acknowledged that not all Chris-tians accept the science behind global warming. They said they do not expect fellow believers to back any proposed solutions that would violate Scripture, such as advocating population control through abortion.

However, the leaders said that current evidence of global warming is “substantial,” and that the threat is too grave to wait for perfect knowledge about whether, or how much, people contribute to the trend.

“We believe our current denominational resolutions and engagement with these issues have often been too timid,” according to the statement. No one speaks on behalf of all Southern Baptists, who leave decision-making to local churches.