Launching mirrors into space, mimicking volcanic eruptions and fertilizing oceans with iron — these processes are no science fiction. They belong to the very real and increasingly publicized field of geo-engineering, which has made its way onto the stage of climate change as a potential deterrent of global warming.

Students and faculty alike gathered in Snee Hall yesterday evening for an earth and atmospheric sciences seminar entitled “Geo-engineering: Is Counter-Balancing Climate Change a Realistic Option” featuring Dr. Michael MacCracken, the chief scientist for climate change programs at the Climate Institute.

MacCracken, also a scientific reviewer for the Intergovernmental Panel on Climate Change, discussed climate change trends and predictions, explaining that dramatic cuts in greenhouse gas emissions are necessary to put the brakes on global warming.

To date, the concentrations of carbon dioxide in the atmosphere have already been associated with a rise of 0.8 degree Celsius. Cutting back on emissions may not be enough, according to MacCracken; geo-engineering provides a potential hedging strategy to deter global warming.

Geo-engineering attempts to reverse global warming through three strategies: reducing the quantities of greenhouse gases in the atmosphere, reducing incoming solar radiation and altering the processes that lead to climate change. In other words, geo-engineering entails deliberately modifying the environment on a planetary scale.

Graphic effects: Dr. Michael MacCracken of the Climate Institute speaks at a geo-engineering lecture on climate change yesterday in Snee Hall.

Proposed geo-engineering pathways range from mass reforestation, in order to take carbon dioxide out of the atmosphere, to fertilizing oceans with iron and other nutrients to stimulate phytoplankton that would also serve collectively as a carbon sink. Another method involves spraying the stratosphere with sulfate aerosols that would deflect sunlight back into space.

These proposals do not come without the risk of side effects. For example, the environmental impact of limiting direct solar radiation might change the color of the sky. Altering natural carbon storage rates could have several biospheric side effects as well.

MacCracken’s twist on geo-engineering emphasizes focused “impact interventions” with more specific goals, with the aim of ultimately benefiting the global warming cause. These specific geo-engineering interventions would approach problems on a local scale with the intent of benefiting the planet in the long run.

“The trouble with the issue of global warming is that, as scientists, we think globally and move downward, but the impacts of global warming occur locally and move upward,” he said.

In one example, MacCracken cited the possibility of reversing Arctic warming, a task that, if accomplished, would have numerous benefits at a relatively small cost.

He suggested techniques to alter the energy balance in the Arctic, such as carefully and sensibly injecting sulfate aerosols into the lower reaches of the stratosphere. The particles would deflect incoming radiation and help slow the melting of the Arctic sea ice.

In the question-and-answer session that followed the seminar, members of the audience voiced concerns over ethics and governance, two issues that continue to prove problematic for geo-engineering.

MacCracken addressed the issue that the implementation of geo-engineering on a planetary scale might lead to the impression that natural events would no longer be considered supernatural, but man-made.

Prof. Robert Kay, earth and atmospheric sciences, expressed slight optimism in the ability of scientists to figure out some of the unknowns.

“The uncertainties behind regional climate variability are certainly trackable and answerable,” he said.

Prof. Gang Chen, earth and atmospheric sciences, expressed a similar sentiment. “[Dr. MacCracken] posed some very intriguing ideas concerning very important issues around global warming,” he said. “I’m still not sure as to what approach is best — nobody knows — but it’s clear that different countries and governments need to come together to address these issues collectively.”