Over the past two years, a team of Canadian and American researchers has evaluated the potential for so-called geo-engineering to address global warming.
They looked at approaches already widely in place like forest and soil management, as well as more controversial ideas such as ocean fertilization and solar radiation management.
What they found is that none of these — or even all of them together — compare to the impact of reductions in human-generated greenhouse gas emissions.
"Politicians don't say directly 'Don't worry, technology will come along and save us,' but it's implied by the continual delay of doing any real climate policy," said Jonn Axsen, an assistant professor at Simon Fraser University's School of Resource and Environmental Management and one of six authors of the study.
The outlook for that last-minute scientific solution is not good, he and his colleagues found.
"There is no silver bullet. There's no technology fix," Axsen said Wednesday. "There's no button that we're going to press some day to reduce the warming that we're going to experience. what we need to do is have climate policy now and start creating real action now.
The team looked at the cost, feasibility and ecological risks of each approach. They also factored in the ability to govern each, the ethics and public acceptance.
They also looked at reduction of greenhouse gas emissions through energy efficiency, conservation and changes in vehicle fuel.
"Abatement of greenhouse-gas emissions should remain the focus of climate-change policy," said the peer-reviewed study, published in the latest issue of the journal Frontier in Ecology and the Environment.
"Given their associated uncertainties and risks, climate engineering strategies best serve as complements to abatement."
Improved management of forests and agriculture are already gaining ground. They are of relatively low risk and generate the least ethical concerns, the study found.
Likewise, there are carbon capture and storage projects now in place on a small scale in some regions, to capture large CO2 releases and prevent their release into the atmosphere by funnelling them into storage, usually deep underground.
Ocean fertilization and solar radiation management are more controversial.
Also called "global cooling," solar radiation management means reducing the heating effect of the sun on Earth. In theory, aerosols sprayed into the atmosphere, outer-atmosphere reflectors or even whitening the surfaces of cities and oceans could reduce that radiant heat.
In ocean fertilization, proponents believe a large deposit of iron-ore in the deep seas will cause an algae bloom that captures carbon and takes it to the ocean floor as it decays. The practice is unproven.
Canada unwittingly became Ground Zero for ocean fertilization research when an unauthorized experiment was carried out off the B.C. coast in July 2012.
The Haida Salmon Restoration Corp. dumped more than 100 metric tonnes of iron into the ocean near Haida Gwaii, hoping it would boost salmon returns and lead to carbon capture profits.
Jason McNamee, who was a director of the corporation, said despite the outcry and controversy, geo-engineering research will continue.
Greenhouse gas emissions show no sign of slowing down, he said. The human population is on course to hit 10 billion by 2050, consumption patterns continue to grow and there is currently no realistic alternative to fossil fuels.
Meanwhile, global fisheries continue to decline, he said.
"It seems that action is required to find methods to reduce our impact on future generations," McNamee said.
"With respect to ocean fertilization we do not know what the risks truly are because there is such a profound paucity of data."