For a Canadian politician, speaking out was empowering.

Organizers of the second Women’s March in Ottawa shifted the focus to issues directly affecting Canadian women. Many marchers wore red scarves as a gesture of support for the large number of indigenous women whose murders or disappearances have received relatively little attention from the police.

The march, which began at the Parliament buildings, was one of about three dozen across Canada.

Among those who addressed the crowd in Ottawa was Catherine McKenna, the environment minister, who has been one of the leading international voices against President Trump’s climate policies.

Late last year, Ms. McKenna confronted a reporter from a right-wing Canadian news outlet, Rebel Media, over its repeated references to her as Climate Barbie. Earlier, a Conservative member of Parliament apologized for describing her that way on Twitter.

“I realized that when I spoke out in my small case of being called Climate Barbie — when I did it I felt better, but I also saw that so many other people stood up for me and they also felt empowered,” Ms. McKenna said in an interview outside of a concert venue at the end of the march.

Although Ms. McKenna credited Prime Minister Justin Trudeau, who regularly describes himself as a feminist, for encouraging women to enter politics, she said their numbers still must increase, and not just in Canada.

“I really believe that we wouldn’t have had an ambitious Paris climate agreement if we didn’t have strong women negotiators,” she said. “That’s one of the untold stories.”