Given the chaos caused by erupting volcanoes this year, the idea of creating a fake eruption sounds like lunacy. Who would wish further mayhem on an already wayward weather system? Yet this is just one of a number of ideas for controlling the elements mooted by climate scientists as a solution to rising temperatures.
Other methods include whitening clouds, shooting mirrors into space and cloaking the Sahara in reflective material. The term for these ideas is climate geoengineering, specifically solar radiation management (SRM). Within a few years this acronym may be as familiar as CO2 emissions and climate change are today.
Messing about with the sun doesn't sound a natural solution to climate disaster, but it is not the preserve of cranks and despots. And it's probably closer than you imagine. Bill Gates recently gave $4.5m to researchers who model weather systems to better understand climate risks, of which $300,000 ended up with a controversial cloud-whitening experiment. Last year the Royal Society published a report on the issue, "Geoengineering the climate". It responds to the continued failure of politicians to tackle the escalating volume of greenhouse gases in the atmosphere. "Efforts to reduce emissions have not yet been sufficiently successful to provide confidence that the reductions needed to avoid dangerous climate change will be achieved," it says. "This has led to growing interest in geoengineering, defined as the deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change."
Dr Nem Vaughan is a fellow of UEA's Tyndall Centre for Climate Change Research and an expert in potential temperature-reducing technologies. She explains that SRM works by intervening in the amount of sunlight coming down to the earth. There are a number of ways of attempting this. The artificial volcanic eruption would involve injecting sulphur aerosols into the stratosphere – above the weather – that could be carried by aircraft. The idea gained legs following the eruption of the Philippines' Mount Pinatubo in 1991, which led to a global temperature dip of 0.5C and a temporary drop in ozone depletion.
Cloud whitening would involve a fleet of ships shooting seawater into clouds, increasing their density and whiteness, therefore reflectivity, so more of the sun's rays were deflected.
The concept of covering the Sahara with mirrors is unworkable, according to Mike Childs, Friends of the Earth's head of campaigns, because of the expense and the vast area involved. "For a start," he says, "these mirrors would need cleaning. How could we do that? As for putting mirrors in space, to us that seems like the stuff of science fiction."
Rainmaking isn't a new idea. Ceremonial rain dances are still performed by societies that rely on agriculture for subsistence. Nor is scientific experimentation with the weather a 21st century invention. A process called cloud seeding has been around since the beginning of the 20th century, when attempts to change the structure of clouds and increase rainfall by spraying substances into the air began, starting in earnest in the 1940s. During the Vietnam War, Operation Popeye tried to slow the Vietnamese army by flooding their roads. Last October China said the blue skies that accompanied Beijing's celebration of 60 years of communism were bespoke, flushed clear by 18 cloud-seeding jets and 432 rockets sent to put a stopper in the skies. The same process was used for the Olympic opening ceremony. In November, droughts led the Beijing Weather Modification Office in the opposite direction, and an 11-hour snowfall was attributed to the 186 rockets scrambled to induce precipitation.
It sounds like playing God, but the worry for environmentalists is who the god might be. Is he Bill Gates, who has reportedly donated millions of dollars to the cause, including funds for Silver Lining, the San Franciscan research body led by Dr Armand Neukermans that will trial cloud-whitening using 10 ships over an area of 10,000km3? Not exactly: the recipients of the Gates' millions, Ken Caldeira of the Carnegie Institute of Science and David Keith of the University of Calgary, gave Neukermans money to investigate spraying seawater in a lab before Silver Lining existed and will not fund field experiments. "The primary goal is to provide information that will help to lead to lower greenhouse gas emissions and diminished environmental risk," says Caldeira. "I would not support anything that I believed was helping to produce a riskier world."
How about a Richard Branson? Kim Jong-il perhaps? Few regulations are in place to stop individuals or governments from starting localised climate geoengineering, which would probably have a global outcome. "Geoengineering may not require collective international effort to have an impact on climate," wrote David Victor, a Stanford energy policy expert, in the Oxford Review of Economic Policy. "A lone Greenfinger, self-appointed protector of the planet and working with a small fraction of the Gates bank account could force a lot of geoengineering on his own."
Mike Childs says climate geoengineering is "within the realms of one mad eccentric", referring to the notion of injecting sulphates into the skies. "We don't know how it will impact upon regional weather," he says. "You don't want to save some farmers from floods only to force farmers on the other side of the world to go through the same thing." Dr Vaughan says where cloud whitening is concerned, it is possible to experiment on a small area and switch it off with no long-term effects. She also says, as the Royal Society report recommends, that while global governance should be a priority, there are pre-existing UN regulations covering unilateral actions that impact upon other countries. The way the International Maritime Organisation managed ocean fertilisation shows how it can be done.
Ocean fertilisation comes from the other arm of climate geoengineering, which focuses on capturing excess carbon and storing it in a safe place. With ocean fertilisation that is the seabed: iron is added to the sea to boost numbers of phytoplankton that absorb CO2, then sink to the bottom of the ocean. Another method is to build enormous artificial trees to suck up carbon much as real trees do. All carbon capture schemes require somewhere to store the gas. Underground porous rock, biochar buried in soil or underground spaces would do the job, but would be needed on a massive scale. Afforestation – planting trees – is a more obvious option, but runs into problems because of competition over land use.
Carbon capture and storage is superior to SRM because it attacks the root cause of climate change. Another fear about SRM is that the side effects on ocean acidification, which could kill millions of sea creatures, are unknown.
The ideal will always be mitigation, shorthand for reducing the global carbon footprint by any means possible and with a coherent international plan. "The role for SRM," says Vaughan, "if at all, depends on whether you've done all the other things and how fast and well they've been done."
In the absence of international mitigation plans, environmentalists are weighing up scientific options. "I don't know an environmentalist who wants geoengineering," says Childs. "But we must investigate the science. The methods which seem safe are artificial trees and afforestation."
The first major conference on "Climate Intervention Technologies" was held in California this year, reflecting the rapid advancement of the concept of climate geoengineering. The conference wouldn't have been necessary if countries could agree to reduce emissions instead of sidestepping them. As yet it is unclear whether these techniques to battle the sun will be a way out of climate chaos or a hi-tech booby trap.