Outgoing US President Barack Obama has banned new oil and gas drilling in millions of acres in the Arctic and Atlantic Oceans.
President Obama used a little-known law called the Outer Continental Shelf Lands Act to protect 115m acres of the Chukchi and Beaufort seas in the Arctic, off the coast of Alaska, in a bid to leave his stamp on the environment before President-elect Donald Trump takes office next month.
He has also protected a series of canyons covering 3.8m acres in the Atlantic, which string from Massachusetts to Virginia. This will put much of the eastern seaboard off limits to oil exploration.
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Billionaire tycoon-turned-politician Trump has said he will expand offshore oil and gas drilling, with a recent memo from his transition team pointing to expansion in the areas Obama has put off limits.
Obama and Canadian Prime Minister Justin Trudeau jointly announced their move to shield areas of the US and Canada's Arctic waters from drilling.
In a statement, the White House said: "These actions, and Canada's parallel actions, protect a sensitive and unique ecosystem that is unlike any other region on earth."
Canada will designate all Arctic Canadian waters as indefinitely off limits to future offshore Arctic oil and gas licensing, which will be reviewed every five years.
It is unclear whether Obama's ban will be watertight, however. Oil industry group the American Petroleum Institute (API) has disagreed about how permanent it will be and said it would be within Trump's powers to lift it.
"We are hopeful the incoming administration will reverse this decision as the nation continues to need a robust strategy for developing offshore and onshore energy,” said Erik Milito, API's upstream director.
Last year, 0.1 per cent of US federal offshore crude production came from the Arctic and there is currently no crude oil production in the Canadian Arctic.
Trump's advisers have also indicated they want access to oil, gas and other natural resources under 56m acres of Native American reservations. To access this federally-owned land, it would need to be privatised.