Story highlights

Shell began work on its controversial Arctic project Sunday

An ice floe forced the company to halt work on Monday

Shell says it can safely drill off Alaska's coast

Environmental groups say a spill there would be catastrophic

CNN —  

An ice floe forced oil giant Royal Dutch Shell to call off its preparatory drilling off Alaska just a day after the controversial work started, the company announced Monday.

The drifting chunk of ice, more than 32 miles long by 12 miles wide, forced the drill ship Noble Discoverer to move off the planned well as a precaution, company spokesman Curtis Smith said. But the ship will be re-anchored within the next few days, and drilling will resume, Smith said.

Shell began work on its planned well in the Chukchi Sea, about 90 miles off the Alaskan North Slope, on Sunday. The Interior Department granted the company permission to begin “certain limited preparatory activities” – including work related to the installation of a blowout preventer – on August 30.

Shell’s plans had been held up by BP’s disastrous 2010 oil spill in the Gulf of Mexico, which prompted a review of offshore drilling plans. Environmental groups argued against the project, warning that a spill would be difficult to plug and clean up in the remote and inhospitable Arctic.

Shell says it’s working at far less depth and lower pressures than the BP well that erupted off Louisiana, destroying the Deepwater Horizon drill rig and killing 11 men aboard.

But Steve Oomittuk, the mayor of the Alaskan coastal town of Point Hope, said he’s keeping a wary eye on the Shell operation and has concerns about what the future will bring.

“There’s nothing we can do now but I worry about the weather and the animals we depend on for our survival,” he said. If “Shell finds what it thinks is down there then many other companies are going to come and then it will only be a matter of time before something happens out there.”

The U.S. Geological Survey estimates more than 90 billion barrels of oil and nearly 1,700 trillion cubic feet of natural gas may be recoverable.

The shrinking of the region’s sea ice – which hit record lows this year – has created new opportunities for energy exploration in the region. The amount of the Arctic covered by sea ice fell in late August to the lowest point since satellite observations began in 1979, the National Snow and Ice Data Center reported.

That trend has stretched into September, with 45% less coverage than September conditions in the 1980s and 1990s.

Climate researchers say this decrease in sea ice a symptom of a warming climate, caused largely by the combustion of carbon-rich fossil fuels. The science is politically controversial but generally accepted as fact by most scientists.

CNN’s Miguel Marquez contributed to this report.