The top award in the 2011 Prime Minister's Science Prizes, worth $500,000, has been awarded to scientists who debunked the theory that fertilising large tracts of the Southern Ocean with iron would help combat climate change.
The theory is that the iron will fuel algal growth, which will then suck up carbon dioxide from the atmosphere - enough to help reduce climate change - and take it to the bottom of the ocean when the algae dies.
But the nine scientists, from Otago University and NIWA, who poured iron solutions into the Southern Ocean and the Gulf of Alaska - which fuelled algal blooms big enough to be seen from space - found the algae took up less carbon dioxide than expected and actually released other, more potent, greenhouse gases.
There was a growing lobby, including influential people like Bill Gates, keen on using geo-engineering to claw back some of the carbon dioxide humans are emitting, team leader Professor Philip Boyd said on Friday.
"Our research has shown that adding iron to the ocean is not going to be an effective way to do that.
"We are increasingly aware that careful stewardship is needed. If we are going to pass on a pristine environment to future generations, we have to understand why the climate is changing and what effects it will have on the ocean."
The team plans to use $400,000 of the prize to study Southern Ocean phytoplankton.
Meanwhile, the Prime Minister's MacDiarmid Emerging Scientist prize, worth $200,000, has been awarded to Victoria University's Rob McKay.
Dr McKay used marine sedimentary records and glacial deposits to reconstruct 13 million years of melting and cooling in Antarctica to show how they influenced global sea levels and climate.
The science media communication prize, worth $100,000, was awarded to University of Canterbury geologist Mark Quigley, who published seven peer-reviewed research articles and delivered more than 40 lectures on the Christchurch earthquakes.
NZN