James Shaw took the stage at the School Strike for Climate Change to tell students it was "time for the talking to stop and the action to start".
Thousands of students skipped school to today to urge Government to take urgent action against climate change.
It was the Climate Change Minister's first public appearance after being assaulted walking to work yesterday.
"Politicians have been talking about climate change for 30 years... It is time for the talking to stop and the action to start," he told the crowd.
He said that was why the Government was committed to passing the Zero Carbon Act this year.
"Climate change is the greatest challenge of our time. It is the greatest challenge of all time.
"The people who have denied and obfuscated and stopped us for the last 30 years, they said, 'climate change isn't real'."
"When we told them it is real, they said, 'it wasn't us', and when we found out it was us they said, 'it can't be that bad'.
What we are here to say is that it is real, it is us, it is bad.... and we can fix it."