TOKYO (Reuters) - Japanese environment minister Shinjiro Koizumi’s call to make climate change “cool” and “sexy” rang false to some Japanese activists on Tuesday, who said he needed to lay down some clear policy.

FILE PHOTO: Japan's new Environment Minister Shinjiro Koizumi leaves Prime Minister Shinzo Abe's official residence in Tokyo, Japan September 11, 2019. REUTERS/Issei Kato

Koizumi, speaking at the weekend before the start of a United Nations climate summit in New York, promised to mobilize young people to create a low-carbon future for coal-dependent Japan, which also emphasizes nuclear power.

“On tackling such a big-scale issue like climate change, it’s got to be fun, it’s got to be cool. It’s got to be sexy too,” the 38-year-old Koizumi, son of a former prime minister and often seen as a future prime minister himself, told a news conference.

But Japanese climate activists and opposition politicians said Koizumi, who on his first day in office also called for Japan to get rid of nuclear reactors, needs to start showing signs of action - or at least policy details - soon.

“We had hopes for Koizumi because his age is closer to us, but he didn’t respond well,” said Takuro Kajiwara, a university student who said he had expected hard policy details.

“We’re just so disappointed, we’re devastated,” he said. The 18-year-old helped organize a protest march through some of Tokyo’s most trendy areas last Friday, joining hundreds of thousands worldwide calling on governments to control greenhouse gas emissions.

“I think he doesn’t understand the climate crisis. He said ‘sexy’ and it didn’t really make sense,” Kajiwara added. “As one Japanese citizen, I am embarrassed.”

Koizumi became the third-youngest lawmaker to join a post-World War Two Japanese cabinet when Prime Minister Shinzo Abe reshuffled his government earlier this month. The telegenic son of charismatic ex-prime minister Junichiro Koizumi, he regularly tops polls as the lawmaker Japanese want to see take over when Abe steps down.

Seasoned climate activists said they welcomed Koizumi’s statements as something fresh from a government that has balked at serious reform and instead plans to build new coal-fired power plants.

“Of course there’s no content to this ‘sexy’ stuff, but Japan’s actions on climate change up to now haven’t been impressive, and if he’s really trying to change things we can’t wholly discount his words,” said Kimiko Hirata, international director at the Kiko Network, a Japanese NGO.

“He’s said a lot of things, now he has to start carrying them out - or become known as being words and nothing else,” she added.

Yuichiro Tamaki, head of Japan’s largest opposition party, was scathing, tweeting that he wanted to see how Koizumi would manage to make Japan both coal- and nuclear-power free.

“We can no longer accept ‘without giving details,’” he added.