Police arrested 13 activists on Sept. 15 who were protesting oil and natural gas leasing on federal lands at the U.S. Department of the Interior, which is the agency responsible for auctioning rights to drill.

The protesters from groups including Friends of the Earth, Rainforest Action Network and Native American communities are part of a wide-ranging so-called Keep It in the Ground network.

The network has grown after a report published in the journal Nature in early 2015 said 80% of the world's remaining oil, gas and coal must be left in the ground if the worst effects of climate change are to be avoided.

"We don't want any more lease sales in Alaska offshore," said Faith Gemmill from Arctic Village, Alaska, a place of about 150 Gwich'in Alaska Natives. "We see the impacts of climate change every day. The ground in Alaska is literally melting beneath our feet; communities are crumbling into the ocean and need to be relocated," she said.

The protesters planned to deliver a petition to stop lease sales, which they said was signed by 1 million people, to Interior Secretary Sally Jewell.

U.S. environmental law provides for mixed use of public lands, including recreation and resource development. Energy companies that drill on U.S. lands claim to produce oil in a more environmentally friendly way than some oil that is produced in countries like Canada or Venezuela.

The threat of environmental protests has stopped or delayed several U.S. oil and gas lease sales at venues across the country this year.

The Interior Department will conduct an online lease sale on Sept. 20. Activitsts contend that this move was forced by their actions during the last year. The department "respects the right of citizens to express their views in a peaceful and lawful manner," spokeswoman Jessica Kershaw said.

Besides protests of lease sales, Keep it in the Ground activists have also built a movement against the Dakota Access Pipeline, which would bring crude from North Dakota to the Gulf Coast states.

Hillary Clinton, the Democratic candidate for president, has said she would be tougher than President Barack Obama on drillers on public lands. Her energy plan would raise fees and give renewable energy like wind and solar an even playing field with oil and gas to develop on the lands.

Donald Trump, the Republican candidate, wants to increase oil and gas drilling.

Erich Pica, the president of Friends of the Earth and one of those who was arrested, said environmentalists would hold Clinton, if elected, to her promises.

"We won't be afraid to hold her accountable. We will push, cajole, protest during the next four years. If we don't get what we want we can always support another Bernie Sanders-type challenger to emerge in the next primary," Pica said.

Sen. Bernie Sanders, D-Vt., who challenged Clinton for the Democratic nomination, supports legislation to keep oil and gas in the ground.