TheAlaska North Slope orAlaska Arctic Slope (Iñupiaq:Siḷaliñiq[1]) is the region of theU.S. state ofAlaska located on the northern slope of theBrooks Range along the coast of twomarginal seas of theArctic Ocean, theChukchi Sea being on the western side ofPoint Barrow, and theBeaufort Sea on the eastern. With the exception of the highway connectingFairbanks toPrudhoe Bay, the region is disconnected from the rest of the Alaskan road system and relies mostly on waterways and small airports for transportation due to the Brooks Range secluding the region from the rest of the state.[2]
The entire Arcticcoastal plain of Alaska with itsArctic coastal tundra has tremendous ecological importance with the densest concentration of birds in the Arctic, along with housing substantial amounts of large mammals such as whales, walrus, seals, caribou, and moose.[2] The region includes theArctic National Wildlife Refuge (ANWR) as well as theNational Petroleum Reserve–Alaska (NPRA).
Within the North Slope, only a surface "active layer" of thetundra thaws each season; most of the soil is permanently frozen year-round. On top of thispermafrost, water flows out to sea via shallow,braided streams or settles into pools and ponds.[3] Along the bottom of theLandsat 7 image on the right, the rugged terrain of the Brooks Range mountains is snow-covered in places (blue areas) and exposed (pink areas) in others.
Much of the region is located politically inNorth Slope Borough, and geographically in theAlaska North Slope basin.
On August 12, 2018, a6.4 magnitude earthquake hit the region, the most powerful recorded for the Alaskan North Slope.[4]
The region includes theArctic National Wildlife Refuge. The entirecoastal plain of Alaska has tremendous ecological importance, with the densest concentration of birds in the Arctic.[5]
Under the North Slope is an ancient seabed, which now contains large amounts ofpetroleum. Within the North Slope, there is a geological feature called the Barrow Arch — a belt of the kind of rock known to be able to serve as a trap for oil. It runs from the city ofUtqiaġvik to a point just west of the Arctic National Wildlife Refuge.[3][6]
Ira Harkey quotesNoel Wien as stating that in the 1920s, "To keep warm and to cook with, theEskimo was burning hunks of dark stuff he just picked up on the ground all around his tent. This was oil from seepage under the tundra. The Eskimos had always known about the oil, long before there was any drilling for it."[7]
The North Slope region includes theNational Petroleum Reserve–Alaska (NPRA), which was established by PresidentWarren G. Harding in 1923 as an oil supply for the US Navy, though the presence of oil in the region had been known by American whalers for some time.[5] It constituted the bulk of Alaska's knownpetroleum until thePrudhoe Bay Oil Field was discovered (outside the NPRA) in 1968, followed by theKuparuk River oil field in 1969. The petroleum extracted from the region is transferred south by means of theTrans-Alaska Pipeline System toValdez on thePacific Ocean.[3]
In 2005 the USGS estimated that the Arctic Alaska Petroleum Province, encompassing all the lands and adjacent Continental Shelf areas north of the Brooks Range-Herald arch (see map) held more than 50 billion bbl ofoil andnatural-gas liquids and 227 trillion cubic feet of gas.[6]
Thesource rock for the Prudhoe Bay Oil Field and neighboring reserves is also a potential source forunconventionaltight oil andshale gas – possibly containing "up to 2 billion barrels of technically recoverable oil and up to 80 trillion cubic feet of natural gas, according to a 2012 U.S. Geological Survey report."[8]
Alaska North Slope (ANS) is a more expensive waterborne crude oil.[9] Since 1987, Alaska North Slope (ANS) crude production has been in decline.[10]
As of 2020, theU.S. Geological Survey estimated 3.6 billion barrels of oil and 8.9 trillion cubic feet of natural gas inMississippian throughPaleogene strata in the central North Slope of Alaska, which are undiscovered and technically recoverable.[11]
{{cite web}}:|archive-date= /|archive-url= timestamp mismatch; February 7, 2026 suggested (help)Professional Paper 1732–A Oil and Gas Resources of the Arctic Alaska Petroleum Province
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