The Hulahula River in the Arctic National Wildlife Refuge.

The Hulahula River in the Arctic National Wildlife Refuge. Danielle Brigida/Flickr


Why Drilling the Arctic Refuge Will Release a Double Dose of Carbon

In the renewed debate over drilling in the Arctic National Wildlife Refuge, one troubling impact of oil development has been overlooked: Disrupting the annual caribou migration will have a profound effect on the soil and release even more greenhouse gas into the atmosphere.

You can hear them coming long before you can see them. It is like a low, rhythmic singing. Wildlife biologist Karsten Heuer describes it in his book Being Caribou as thrumming. It is the sound collectively made by the 150,000 or more members of the Porcupine caribou herd as they move in concert near the end of their approximately 1,500-mile trek, the longest documented terrestrial mammal migration in the world.

Each spring for at least the past 23,000 years, members of this herd, dispersed across the wide expanses of their wintering grounds in Canada’s Yukon, have gathered together like water flowing along branched tributaries toward a single confluence. That confluence is a 1.5 million-acre area of boggy coastal tundra plain, nestled between the north slope of the Brooks Range in Alaska and the Beaufort Sea. The caribou know this place as their summer calving and feeding ground. We know it as Area 1002 within the larger 19.2 million-acre Arctic National Wildlife Refuge (ANWR).

Last month, on its final day in office, the Trump administration, announced it had auctioned off nine leases for oil and gas development in Area 1002, culminating decades of contention over the future of this coastal plain. The following day, newly inaugurated President Biden imposed a moratorium on all oil and gas leasing in the refuge, questioning the legality of the leases and citing the lack of a required review of environmental impacts on this wilderness.

On its surface, the treeless Area 1002 tundra, with its rolling hills, small lakes and braided rivers, offers an amazing vista. Porcupine caribou zero in on this place because it is an oasis within an otherwise vast and formidable arctic desert. In late spring and summer, Area 1002 is lush with grasses, sedges, forbs, and shrubs that nourish lactating female caribou. It also provides refuge from predators, which prefer habitats on the slopes of the Brooks Range, that would otherwise feast on the tens of thousands of highly vulnerable new-born caribou calves.

Estimates indicate that 10 to 20 pounds of carbon per square foot resides within the uppermost 10 feet of the permafrost.

Below the surface, descending 4 to 5 miles to its basement, is another striking feature of Area 1002, a geological history written in layer upon layer of sedimentary rock dating back 300 to 400 million years to the Devonian period. It is within this geology, and its relationship to the caribou, where we find the story of two carbons.

The one kind of carbon, locked away in the basement geology, is part of a deposit that began to form 50 million years ago in the Eocene Epoch when dead organic matter from marine algae and early land plants and animals was squeezed by the Earth’s pressure to form petroleum-carbon. This process continued for the next 40 million years to build up a reserve estimated to contain between 4.3 and 7.7 billion barrels of extractable oil.

The other kind of carbon, locked away as permafrost-carbon in a 900 to 2,000-foot-thick deposit just below the surface, began to form tens to hundreds of thousands of years ago during the late Pleistocene Epoch, and it continues to build to this day. Estimates indicate that 10 to 20 pounds of carbon per square foot of surface area resides just within the uppermost 10 feet of this geological layer, which amounts to 75 percent of the carbon held within the permafrost soil. This carbon deposit is made up of dead organic matter — from roots, plant leaves, and animals — which exists frozen in suspended animation. That is because for much of the year the frosted soil allows little if any microbial decomposition to proceed. And the caribou, a relic of the Pleistocene, may help to ensure that the permafrost-carbon stays locked up as a consequence of their grazing.

Migrating caribou in the Arctic Refuge's coastal plain.

Migrating caribou in the Arctic Refuge's coastal plain. Gary Braasch/National Wildlife Federation

The caribou begin wandering widely throughout Area 1002 within the few weeks after giving birth, once the calves are able to keep up with their mothers’ daily movement of 10 to 12 miles. They spend the summer from mid-June to early August grazing widely. Current assessments show that this summer grazing provides nourishment that is critical to sustain the health and long-term persistence of the Porcupine caribou herd. What these assessments do not consider, however, is how this grazing may sustain the long-term persistence of the permafrost-carbon.

New studies in other locations throughout the Arctic are increasingly showing that caribou grazing may have a feedback effect that cools the permafrost. Caribou grazing selectively favors the year-round dominance of grasses, sedges, and forbs over shrubs in the plant community. Without caribou grazing, tall shrubs could begin to dominate the landscape. Taller shrubs rise above the snowpack and can cause earlier snowmelt as well as summer permafrost thawing by changing the surface albedo in ways that make the tundra more conducive to absorbing rather than reflecting heat from the sun. A thawing permafrost in turn re-animates microbial decomposition of organic matter.

All would be well here, if it weren’t for the fact that since 1987, various interests have sought authorization to unlock all of the petroleum-carbon held in the reserve below Area 1002, leading to the Trump administration’s sale of oil and gas leases last month. This has raised concerns about the fate of numerous wildlife species that depend on Area 1002 during the summer, as well as about the ethics of impacting an area within the largest unfettered wilderness in the world.

Of particular concern is the assessed risk that the population size of the Porcupine caribou herd will crash. Caribou are highly sensitive to activity and infrastructure associated with oil and gas exploration and extraction. Conservation groups worry that such activity could drive the caribou to abandon Area 1002 altogether, leading to the loss of access to critical nourishment and a population collapse. Proponents of exploitation counter that oil extraction can be done in ways that minimize the risk of causing the caribou population to decline.

The key issue is what happens to caribou movements and to the soil that risks becoming unlocked due to thawing.

But both sides of the debate miss an important point. Even if caribou population size can be sustained, the salient issue is ultimately what happens to caribou summer movements throughout Area 1002 and to the near-surface soil carbon that risks becoming unlocked due to permafrost thawing.

Normally microbial decomposition in aerated soils releases CO2 to the atmosphere. If that were the case in Area 1002, decomposition of the 300 to 600 megatons of carbon held within the 3-meter-thick layer across the entire Area 1002 could release 1.1 to 2.2 gigatons of CO2 into the atmosphere. This is equivalent to between 12 and 25 percent of the CO2 that would be released if the 4.4 billion barrels of oil dug out of the basement geology of Area 1002 were to be burned. However, wet boggy conditions, such as those found in Area 1002, are anaerobic. Consequently, microbial decomposition is highly likely to release the carbon as methane. Although the mass of methane that would be released is one-third of the mass of CO2 and remains in the atmosphere for one-tenth of the time that CO2 does, methane has a 85 times more potent greenhouse gas heat-trapping effect than CO2 over a 20-year period. The near-term climate consequences of methane vs CO2 building-up in the atmosphere more than makes up for the lower amount released and time remaining in the atmosphere.

In 2017, the Trump administration secured congressional authorization to open Area 1002 for oil and gas development and went ahead with the auctioning of leases in January. But oil companies had little interest in submitting bids. The reasons include economic concerns about oil being in low demand and unease about its future market; uncertainty about the exact amount of extractable oil that actually exists in Area 1002; and the high costs of oil exploration in such a remote place. Oil companies have also faced pressures from investors and activists concerned about the irresponsibility of exacerbating the climate crisis, as well as the negative public opinion that would result from the irreparable damage that would be inflicted on this iconic place.

A caribou moves through cotton grass in the Arctic National Wildlife Refuge.

A caribou moves through cotton grass in the Arctic National Wildlife Refuge. Danielle Brigida/Flickr

In the absence of bidding by oil companies, Alaska’s state-owned economic development corporation moved in to fill the void. The state’s action was spurred by the U.S. Geological Service’s cost-benefit analyses that oil extraction in Area 1002 could be a profitable venture, bringing benefits through job creation and tax revenues. The State of Alaska intends now to undertake seismic exploration throughout Area 1002 to pinpoint locations where drilling could be profitable, with the intent of laying the groundwork for attracting industry at a future date.

But the benefit-cost analysis that informed Alaska’s decision failed to consider the social cost of carbon — usually measured as the dollar value of harm caused by emitting a fixed amount of CO2 into the atmosphere. That cost may be exacerbated if seismic activities risk the release of permafrost-carbon as methane by altering caribou movement and grazing. Accounting for the cost in terms of methane released could significantly tip the economic balance. In the worst case, the additional social cost of methane-caused global warming could, over the expected 30-year lifespan of oil extraction in Area 1002, wipe out most if not all of the expected tax revenue from oil activity going to the state.

Currently, the exact social cost of carbon taking into account the potency and lifespan of methane released to the atmosphere remains uncertain. That is because environmental risk assessments have not evaluated how widespread the thawing of permafrost in Area 1002 will be as a consequence of shifting caribou movement, nor have they determined the rate at which the thawing top 10-foot-layer of permafrost will be decomposed. Still, decades-old preliminary exploration activity in Area 1002 would suggest, at the very least, that the spectacular wilderness vista will be altered for generations to come.

Beyond the analyses, the ultimate question remains: Will this economically questionable 30-year venture be worth the lasting environmental consequences to a wilderness that took tens to hundreds of thousands of years to develop, for the sake of extracting what amounts to meeting one year’s worth of the nation’s oil demand?