Ms. Swarbrick is commenting on the Zero Carbon Act, which aims to reduce New Zealand's net carbon emissions to zero by 2050.
Explaining why she used the phrase in a text message to Stuff, Ms Swarbrick said it was a It's a "simple summarisation of collective exhaustion".
Without missing a beat, Ms Swarbrick raised a hand and retorted, "OK, boomer" before continuing to talk about climate.
"Mr. Speaker, what number of world leaders for what number of many years have seen and recognized what's coming, however have determined that it's extra politically expedient to maintain [climate change] behind closed doorways?" she requested.
"Climate action can not be sacrificed any more for political convenience", she said.
"I will be 56 by 2050".
The videos usually include an audio clip of an older man saying, "The millennials and Generation Z have the Peter Pan syndrome, they don't ever want to grow up".
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Police and home ministry officials said government agencies were making preparations to thwart any violence. Meanwhile, political parties in the city also appealed to people to maintain peace after the verdict.
"It's as if OK boomer says, 'OK, you baby boomer".
She said it acknowledges that 'you can not win a deeply polarised debate - facts don't matter. "It's higher to acknowledge that maybe power is healthier spent elsewhere".
Writing on Facebook after her comment went viral, Ms Swarbrick wrote: 'Today I have learnt that responding succinctly and in ideal jest to somebody heckling you about *your ageyour generation* with the literal title of their generation makes some people very mad.
"That rallying cry is the relatively innocuous "okay boomer".
The phrase is so new, captioning of Swarbrick's speech didn't even pick up on it, New Zealand Herald reporter Jason Walls noted.
Young people have suffered a decade of jibes about how millennials have ruined everything and need to "pull our socks up, or something", she said.
The parliament's social media team apologized for the error and said the captions were updated.
"It's kind of a unintentionally crowd-sourced explanation of frustration summarized in one symbolic, swift sentence", Swarbrick said. In response to the trend, Steve Cuozzo, columnist for the New York Post, recently published a column titled "Millennials' extreme hatred for Baby Boomers is totally unjustified", where he ranted about the youth's love for avocados and kale, their overuse of iPhones, and their inability to work hard like he did back in the day.