Scientists are again warning urgent action is needed on climate change as New Zealand notches up a troubling milestone.
Scientists monitoring climate change and New Zealand's impact on the earth's atmosphere at Baring Head at the bottom of the North Island have now recorded carbon dioxide concentration in the atmosphere at 400 parts per million.
"It's not that anything special happens at 400 parts per million. It's more like reaching your 40th birthday and realising that you haven't started saving for retirement. It's a natural time to stop and take stock," said Dr Sara Mikaloff-Fletcher, an atmosphere-ocean scientist.
Dr Mikaloff-Fletcher says this is one of the last places on earth to hit the mark. It was reached in the Northern Hemisphere three years ago.
She says time is running out to tackle climate change and lists some of the risks that are rising.
"It's substantial sea level rise which will have a big impact on coastal communities, more risk of wild fires, more risk of flooding as well. Pressure on fresh water resources."
Climate scientist Professor James Renwick of Victoria University says the CO2 level of 400 parts per million "is pretty close to the limit where you start to get irreversible melting of parts of the Antarctic ice sheets and the Greenland ice sheet".
Professor Renwick says despite signing up to both the Kyoto and Paris agreements, New Zealand is doing very little to reduce emissions.
"The projections are they'll keep going up. And the only way we're meeting our targets is by trading internationally - so riding on the back of people elsewhere who are actually reducing their emissions," he said.