Norwegian cousins battle over oil, climate policy
Fourteen years on, they now find themselves divided by climate politics: Eriksen is the environment minister in the oil-rich country, while Berg is one of his biggest activist critics.
A militant with the Extinction Rebellion climate group, Berg has vowed to start a hunger strike on Wednesday to press the pro-oil, centre-left government to abandon drilling for the sake of the planet.
The protest will put his cousin on the spot as Norway prepares for a general election on September 8 in which its crucial oil industry will be a key campaign issue.
Berg, 29, and his 33-year-old cousin were at a youth camp on the island of Utoya on July 22, 2011 when far-right sympathiser Anders Behring Breivik went on a gun rampage that killed 69 people.
Breivik also set off a bomb near government headquarters in Oslo that killed another eight.
"It is clear that going through something like that... yes, it marks a relationship," Berg told AFP in an interview.
But it will not deflect him from his campaign against a Labour government that wants to develop the valuable oil industry further.
"This industry has made us an extremely rich country," Berg said.
"The problem is the price -- potentially the deaths of millions of people because of the ravages caused by this oil and this gas," he added.
"It is not worth us continuing to make ourselves even richer at this price."
Norway's oil riches
Several small parties -- from the left wing to ecologists and centre-right liberals -- back Berg's stance as Norway goes into its election campaign.
But Labour has the support of conservative and hard-right parties in its drive to "develop, not dismantle" the oil sector.
Norway's offshore oil and gas fields have indeed made it rich.
Its sovereign wealth fund, the biggest in the world, is worth nearly $2 trillion -- $350,000 per inhabitant.
"The big parties make it seem like it's never enough," said Berg, born in Stavanger, Norway's oil capital, whose father worked his whole life for petroleum giant Equinor.
"It is a huge moral injustice to continue enriching ourselves further while already being among the richest in the world," he said.
"And that people in other regions, mostly poor, dark-skinned people, simply have to die for us to become even richer."
Holding cousin accountable
Eriksen has declined to comment directly on his cousin's activism, but spoke to the newspaper Dagbladet in July 2024 after Berg was caught trespassing at Oslo airport in a protest.
"I understand that many people are impatient, and I am too. There is an urgent need to reduce emissions to curb climate change," the newspaper quoted Eriksen as saying.
"Vebjorn and I, however, have different views on how the transition should happen and the methods for expressing our opinions. For me, broad support is critical for ensuring the transition stands the test of time."
Berg said he will not vote Labour this year but insisted he and his cousin "appreciate each other a lot", in his comments to AFP.
"Communication between us is both respectful and affectionate. I try to be as honest and direct as possible with him," he said.
"I will do what I can to preserve our relationship while continuing to hold him accountable."