Gretta, your first climate strike was a lonely event a little over a year ago. And in the intervening time, you have sparked the interest of millions literally of children around the globe demanding action for climate change. What's your message to world leaders today?

My message is that we'll be watching you.

This is all wrong. I shouldn't be up here. I should be back in school on the other side of the ocean. Yet you all come to us, young people, for hope.

How dare you?

You have stolen my dreams and my childhood with your empty words, and yet I'm one of the lucky ones. People are suffering. People are dying. Entire ecosystems are collapsing. We are in the beginning of a mass extinction. And all you can talk about is the money in fairy tales of eternal economic growth. How dare you?

For more than 30 years, the science has been crystal clear. How dare you continue to look away and come here saying that you're doing enough when the politics and solutions needed are still nowhere in sights.

You say you hear us and that you understand the urgency. But no matter how sad and angry I am, I do not want to believe that because if you really understood the situation and still kept on failing to act, then you would be evil and that I refuse to believe it. The popular idea of cutting our emissions in half in 10 years only gives us a 50 percent chance of staying below 1.5 degrees and the risk of setting off irreversible chain reactions beyond human control.

50 percent may be acceptable to you. But those numbers do not include tipping points. Most feedback loops, additional warming hidden by toxic air pollution or the aspects of equity and climate justice. They also rely on my generation sucking hundreds of billions of tons of your CO2 out of the air with technologies that barely exist. So a 50 percent risk is simply not acceptable to us. We who have to live with the consequences. To have a 67 percent chance of saying below a 1.5 degrees global temperature rise, the best odds given by the IPCC, the world had 420 gigatons of CO2 left to emit back on January 1st, 2018.

Today, that figure is already down to less than 350 gigatons. How dare you pretend that this can be sold with just business as usual and some technical solutions? With today's emissions levels, that remaining CO2 budgets will be entirely gone within less than eight and a half years. There will not be any solutions or plans presented in line with these figures here today because these numbers are too uncomfortable. You are still not mature enough to tell it like it is.

You are failing us, but the young people are starting to understand your betrayal. The eyes of all future generations are upon you. And if you choose to fail us, I say we will never forgive you. We will not let you get away with this right here, right now is where we draw the line. The world is waking up and change is coming, whether you like it or not.

Thank you.