Geo-engineering our climate
Feb 07 2013
The eruption of Mt Pinatubo, a volcano on the Philippine island of Luzon, on April 2, 1991 is, perhaps, the first evidence on the effectiveness of the geo-engineering approach. According to The New Yorker, Pinatubo had been dormant for more than four centuries. However, starting in April, 1991, the tremors continued in a steady crescendo for the next two months, until June 15, when the mountain exploded with enough force to expel molten lava. Within hours, the plume of gas and ash had penetrated the stratosphere, eventually reaching an altitude of 21 miles. Three weeks later, an aerosol cloud had encircled the earth, and it remained for nearly two years. 20 million metric tonnes of sulfur dioxide mixed with droplets of water created a kind of gaseous mirror that reflected solar rays back into the sky. Throughout 1992 and 1993, the amount of sunlight that reached the surface of the earth was reduced by more than 10 per cent.
The New Yorker believes that the heavy industrial activity of the past 100 years had caused the earth’s climate to warm by roughly three-quarters of a degree celsius; however, the eruption of Mt Pinatubo reduced global temperatures by nearly that much in a single year. Thus, for geo-engineering scientists, Mt Pinatubo provided the best model in at least a century to help us understand what might happen if humans attempted to reduce global warming by deliberately altering the climate of the earth.
However, according to The New Yorker, it is also believed that Mt Pinatubo’s eruption had influenced events as varied as floods along the Mississippi River in 1993 and, later that year, the drought that devastated the African Sahel. Thus, most people considered the eruption a disaster.
In support, the Intergovernmental Panel on Climate Change (IPCC) in its 2007 report concluded that geo-engineering options remained largely unproven. “Let’s face it, geo-engineering has a lot of unknowns,” says Rajendra Pachauri, chairman, IPCC. Similar is the tone echoed by UN’s climate change secretariat: Christiana Figueres, head of the UN Climate Change Secretariat, says that we should emphasise the need to focus on actual greenhouse gas emissions reductions and mitigation strategies first, rather than look for geo-engineering our climate.
According to climate scientists, when we currently grapple with the difficulty of predicting long-term climate change via climate models, then notion of altering the earth’s climate based on the results generated by those models would four-fold compound the worry in our minds. David Keith, a professor of engineering and public policy at Harvard and one of geo-engineering’s most thoughtful supporters says, “When you start to reflect light away from the planet, you can easily imagine a chain of events that would extinguish life on earth.”
However, the truth is that we might need resort to such risky geo-engineering measures given that earth’s temperature is expected to rise between 2.4 and 6.4 degrees celsius at our current rate of development. According to IPCC, tens of thousands of wildfires have already been attributed to global warming, as have melting glaciers and rising seas. (The warming of the oceans is particularly worrisome; as Arctic ice melts, water that was below the surface becomes exposed to the sun and absorbs more solar energy, which leads to warmer oceans — a loop that could rapidly spin out of control.) In fact, according to IPCC, even a 2 degrees celsius climb in average global temperatures could cause crop failures in parts of the world that can least afford to lose the nourishment. The size of deserts would increase, along with the frequency and intensity of wildfires.
With global warming, the Maldives, where the highest point above sea level is just eight feet, may be the first nation to drown. One Australian study, published in 2012 in the journal Nature Climate Change, found that a 2 degrees celsius rise in the earth’s temperature would be accompanied by a significant spike in the number of lives lost just in Brisbane. Also, there is twice as much CO2 locked beneath the tundra as there is in the earth’s atmosphere. Melting the polar ice would release enormous stores of methane, a greenhouse gas nearly thirty times more potent than carbon dioxide. If that happens, according to the hydrologist Jane Long, Lawrence Livermore National Laboratory, “it’s game over.”
Thus, deliberately modifying the earth’s atmosphere through geo-engineering would be a desperate gamble with significant risks, but one that mankind might resort to if no other mitigation or adoption options exist or are exercised. Yet, according to The New Yorker, the more likely climate change is to cause devastation, the more attractive even the most perilous attempts to mitigate those changes will become through geo-engineering.
(The writer is on the faculty of Indian Institute of Technology, Mandi, India)