2012 marked a new record low for the extent of Arctic sea ice, but apparently that's not a problem. We can just refreeze it!
Reducing carbon dioxide emissions is the key to a lasting solution to 'human-enhanced' climate change, however since governments and industries aren't doing a very good job of meeting reduction goals, strategies to reduce the worst effects of climate change may be needed. Dr. David Keith, a Canadian physicist, climate scientist and public policy expert who teaches at Harvard University, has done extensive research into the field of Solar Radiation Management, which involves different ways of reducing the amount of solar radiation that reaches the Earth's surface.
The concept behind solar radiation management is fairly basic: introduce a substance into the environment that will reflect more sunlight back into space, and the resulting reduction in the amount of sunlight that reaches the surface will cause an immediate temperature drop in the affected region. One method of doing this involves spraying reflective aerosols — tiny drops of liquid about the same size as those that make up clouds, such as sulphur dioxide or titanium dioxide — into the stable stratosphere, where they can persist for years. Similar aerosols injected into any level of the troposphere (the lowest level of the atmosphere, where all weather happens) would quickly get caught up in the turbulent weather that we see every day and would not last long enough to help reduce incoming sunlight.
Would this really work? Studying the effects of volcanic eruptions (which is where they got the idea from in the first place) and using computer model simulations have given scientists plenty of evidence that it will.
Some approaches to solar radiation management have tried to deal with the situation on a global scale, with talk of releasing a million tons of sulphur dioxide into the stratosphere to lower the temperature around the world. However, these ideas have come under criticism, because of the potential for unforeseen consequences. For example, it has been suggested that introducing sulphur dioxide into the stratosphere could destroy the Earth's protective ozone layer, exposing us to dangerous ultraviolet radiation from the Sun.
Dr. Keith and his colleagues suggest that much better results could be achieved, with a minimum of risk, by only using solar radiation management on a regional scale. Therefore, rather than spread the reflective substance across the entire stratosphere, we would only use it over the area that needed it. They used a selected climate model to simulate these regional changes, compared to a uniform global change, and according to CalTech News, "it took five times less solar reduction than in the uniform reflectance models to recover the Arctic sea ice to the extent typical of pre-Industrial years."
Injecting just five metric tons of these reflective aerosols into the Arctic stratosphere could lower solar radiation levels over the Arctic Ocean enough to refreeze it and allow it to remain frozen. Before you get too alarmed by that five metric tons, the latest official figures from the US EPA show that in 1999, industry released over 17 million metric tons of sulphur dioxide into the troposphere.
There are down-sides to the plan, of course.
Likely no surprise to anyone, it is going to cost money. Compared to how much the effects of climate change are projected to cost us, or what the costs of reducing emissions will be, though, it is a drop in the bucket. Dr. Keith, along with Justin McClellan, from the Aurora Flight Science Corporation in Cambridge, Massachusetts, and Jay Apt, from Carnegie Mellon University's Tepper School of Business and Department of Engineering and Public Policy, published a cost-analysis report in the journal Environmental Research Letters, in August of this year.
Their report states that the technology to deliver these materials to the right altitude and location already exist, and by modifying existing aircraft to act as the delivery method, the entire effort of running the program would cost between $5-8 billion per year (depending on the method of delivery), with the majority of that cost going towards buying or producing the sulphur dioxide itself. According to the same report (referencing from the 2007 IPCC report) "the costs of climate damages or of emission mitigation are commonly estimated to be 0.2—2.5% of 2030 global GDP... equivalent to roughly $200B to $2000B per year. Our estimates of the cost of delivering mass to the stratosphere — likely to be the most substantial part of the cost of SRM deployment — are less than 1% of this figure."
So, we can do this, and compared to the alternatives, it is fairly cost effective. However, is this something we should be doing?
From the standpoint of the effect of having sea ice as opposed to not having sea ice, we should choose to have the sea ice. Without it, global temperatures will rise even faster than they are now. When the sea ice is there, it reflects back solar radiation into space and limits the amount of warming there is of the planet. Take that sea ice away and the darker water absorbs a large percentage of the incoming solar radiation. This will not only contribute to more melting of sea ice, but will give a generally warmer atmosphere and as the water warms it will expand, causing further rises in sea level.
There is the risk of destroying the stratospheric ozone layer, especially if these reflective aerosols get into the Antarctic stratospheric clouds that accumulate during the winter, which are the primary cause of the Antarctic ozone hole. These chemicals, in higher concentrations, would enhance the destruction of ozone and make the ozone hole even larger. However, using a regional scale approach would allow us to limit the concentrations of the aerosols, and thus limit the damage they cause.
There's one other problem with this idea, though — a general tendency towards quick fixes.
Peter Mooney, with Ottawa's Etc Group, which monitors the effects of technology and corporate strategies on society and the environment told The National Post, "It's naive to think that once [solar radiation management] becomes a political option that governments won't just take it on and interpret it as they wish. They will always find scientists who will give them the spin that they want."
"[We shouldn't be] opening up the back door for politicians to creep out of, claiming that, 'Don't worry folks. We don't need to do anything because we have technological fixes that we can deploy on short notice.'"
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