In an open letter to Norway's Prime Minister Erna Solberg, Hansen, who heads the climate program at Columbia University's Earth Institute, said that how Norway handles the exploitation of the Arctic could have a "massive effect -- for better or for worse".
"Norway is strategically poised to play an important role in the fight to avert catastrophic climate change," he wrote, praising the country's leadership on rainforest protection and ambitious emissions reduction targets.
However, he said that he planned to tell this week's Oslo climate conference and a meeting in Brussels that all of the positive work the country is doing would be completely negated by a decision to drill in the Arctic.
"The decision to license further oil extraction in the Barents Sea, if executed, gives oil companies access to enormous reserves of oil and gas in the very ecosystems most vulnerable to climate change," he wrote. "Prime Minister Solberg, proceeding with the 23rd licensing round would group your country amongst the world's most unrelenting contributors to fossil fuel business-as-usual, making Norway party to the greatest intergenerational injustice ever committed."
Hansen said he had agreed to stand as an expert witness in a law suit soon to be launched by Norwegian campaigners, which aims to force the country to stop the licensing round, citing article 112 in the country's constitution.
He said a decision to leave the oil in the ground would be "an act of leadership that would resound around the world and in history."