Clare Bailey was speaking after a fourth thunderstorm warning in a week was issued by the Met Office, and just weeks after the all-time temperature record was smashed during the July heatwave.
The UN report, published on Monday, warns that humans are unequivocally driving global warming with impacts from heatwaves to rising seas and extreme rain already seen around the world.
It was described as a “frightening wake up call” by Northern Ireland’s Infrastructure Minister Nichola Mallon.
Ms Bailey said: “Monday’s report by the IPCC (Intergovernmental Panel on Climate Change) is a stark reminder that the window to act on climate change is closing. We have seen extreme weather in Northern Ireland in recent weeks and the report predicts more intense heatwaves and increased flooding as temperatures rise. Some changes, such as sea level rise, are irreversible.”
She continued: “Working cross party and with a coalition of civic society, I am leading a Climate Change Bill which puts us on a path to net-zero emissions by 2045 at the latest.
“This report tells us is that there is no time to waste. We need to act now.
“We need to act collectively and with the sense of urgency that this report starkly warns us about.”
She added: “We know what we have to do. We now need to harness a national and global effort to do it. Failure to act will have devastating consequences, particularly for those vulnerable populations who have done the least to cause climate change.”
Ms Mallon, speaking to the BBC, said she would raise the climate change report – described by the UN as a “code red for humanity” – at Thursday’s meeting of Executive ministers at Stormont.
The SDLP minister also highlighted the need for legislation.
“We all rallied as a society to deal with the Covid crisis,” Ms Mallon said. “We need to show the same urgency in terms of tackling the climate crisis.”
She added: “That means getting legislation through the Assembly with ambitious targets.”
Sinn Fein also called for legislation, with the party’s North Antrim MLA Philip McGuigan calling for a Climate Change Act to be a priority for the Assembly.