Stopping an 8,000 ton ship from leaving port may sound like difficult work, but that’s just what activists meant to do when they swarmed the St. Johns Bridge in Portland, Oregon.

Some descended into dangling hammocks, while others took to the water with kayaks in what would turn into a 40-hour standoff between Greenpeace and Royal Dutch Shell.

The protest sought to delay the departure of the Fennica icebreaker, a Shell vessel carrying a piece of equipment necessary to proceed with drilling in Alaska’s Chukchi Sea, under the terms of allowance granted by the Interior Department in May.

After almost two days of stalemate, the ship was escorted by police through the blockade, and toward Arctic waters. Protests like the “Shell No” barricade show just how controversial Arctic drilling is, and how this complex topic may have long term reverberations.

A Brief History of Arctic Drilling

In 2008, the U.S. Geological Survey reported that an estimated 90 billion barrels of recoverable oil lies in the area above the Arctic Circle, most of which would be found in the region’s ocean, including the Chukchi Sea. Along with oil, the Arctic Circle may contain over 1,600 trillion cubic feet of untapped natural gas.

According to the report, “The Arctic accounts for about 13 percent of the undiscovered oil, 30 percent of the undiscovered natural gas, and 20 percent of the undiscovered natural gas liquids in the world,” making it a trove of interest for the fossil fuels industry.

Conditions of the agreement allow for Shell to drill in two exploratory sites during the Arctic’s summer season, which ends in late September, and only in oil-bearing zones if stocked with a capping stack, the equipment aboard the halted Fennica.

The United States is not alone in its interest in these Arctic deposits. In the past few years, Russia, Norway, Canada, Denmark and Iceland have joined the U.S. in the race to excavate fossil fuels from the Arctic Circle.

What Are the Risks?

In a 2013 Oil Spill Risk Analysis, the Bureau of Ocean Energy Management (BOEM) studied the behavior of oil spills in ocean waters through simulated tests of a hypothetical spill’s trajectory. The waters of the Arctic Ocean posed a problem unique to its territory: ice.

“Unlike other regions, sea ice is a factor in the Alaska [Outer Continental Shelf] OCS areas. The transport of real and hypothetical oil spills depends not only on the winds and ocean currents but on ice as well.”

Ice causes an obstacle to the cleanup of potential spills, and a threat to the safety of the workers involved in drilling and exploratory missions.

Soon after the Interior Department’s decision to allow drilling to proceed in the Arctic Ocean, The New York Times wrote that, due to its remoteness, “Both industry and environmental groups say that the Chukchi Sea is one of the most dangerous places in the world to drill.”

In the instance of an accident, help would be hundreds of miles away, and even further would be a Coast Guard station properly equipped to respond to a spill, at over 1,000 miles from drilling zones.

On top of the human health risks, drilling the Arctic comes with the possibility of irreparable ecosystem damage. Noise from drilling could disrupt feeding and migratory patterns of marine animals, leading to population reductions with slow ecological recovery.

Mother Nature Network reported that emissions from gas flaring could raise global CO2 levels substantially. “Burning the Arctic Ocean’s oil could release an additional 15.8 billion tons of CO2 into the atmosphere.”

The Takeaway

Despite regulatory efforts to ensure safety and cleanup response, there is no guarantee that a spill can be prevented. The BOEM estimated that there is a 75 percent chance that a large spill may occur in the lifetime of the wells, and Shell has a history of mishaps in its Arctic endeavors.

The study does not mean that there is 75 percent possibility that Shell’s exploration will result in a spill; this number instead represents the chance of a major spill occurring over the 77 year lifespan of the Arctic oilfields.

Environmental scientists have warned that tapping into these reserves may defy global emissions limitations. To combat further atmospheric warming, the best place for buried fossil fuels like the reserves in the Chukchi Sea may be underground.

Obama’s decision to allow limited drilling in the Arctic has struck climate conscious people as contradictory, considering his pledge to combat climate change. In light of competition from Russia and other countries with stakes in the area, Obama may now be looking to define the borders of Arctic oil territories.