Members of the school's Green Group have used more than 100kg of the invasive seaweed Undaria to create a large "350" on a Quarantine Island hillside.
The 6m-wide and 4m-high sign was created on Friday by the nine pupils and three adults in the Green Group at the conclusion of three days spent clearing the seaweed from the shoreline of the Otago Harbour island.
"We wanted to get the message out about 350," Elizabeth Rudd (17), a secondary school representative on the Dunedin 350 committee, said.
"It is really important that people are aware of the danger we are in and aware that we can do something but need to do it quickly."
People throughout the world needed to let their politicians know they wanted them to take decisive action at December's international climate-change summit in Copenhagen, Denmark, OGHS environment prefect Rosina Scott-Fyfe (17) said.
"The world leaders really need to set a low target for the sake of our future," Rosina said.
Scientists estimated 350 parts per million (ppm) of carbon dioxide in the atmosphere was a safe maximum, OGHS teacher Douglas Black said.
But the present level was 389ppm and rising, he said.
"If we get back there fast it will limit world temperature increases to two degrees. Above that, we get runaway climate change."
Collecting the seaweed was part of a study begun in 2002 examining the impact of Undaria pinnatifida on the local marine environment, Mr Black said.
The highly invasive kelp, which was probably brought to New Zealand in visiting ships' ballast water, has spread to many locations in New Zealand.
The facts
- 350 is an international campaign for a global climate treaty that lowers carbon dioxide in the atmosphere below 350 parts per million (ppm).
- Scientists estimate the maximum safe level of carbon dioxide in the atmosphere is 350ppm. The current level is about 389ppm, rising by about 2ppm per year.
- October 24 is 350's international day of climate action. Groups in more than 100 countries including New Zealand are holding events to raise awareness about the issue in the lead-up to the international climate change summit in Copenhagen, Denmark, in December.
