Humanity has managed to stabilize its carbon emissions, but they have yet to trend downward. It looks increasingly likely that we will emit enough to commit to at least 1.5°C warming – and we must act quickly to avoid warming above 2°C. This failure to get our emissions in order could force us to consider alternatives such as removing carbon dioxide from the air or geoengineering to reduce the amount of sunlight that enters.
Of the two, geoengineering has the longest list of unknowns a recent report from the National Academies of Science: “Scientific understanding of many aspects of solar geoengineering technologies remains limited, including implications for extreme weather, agriculture, natural ecosystems, or human health.”
So, naturally, some Silicon Valley guys decided to go ahead and start a startup that would offer geoengineering for a fee. The company claims to offer warming offsets despite the significant geoengineering unknowns. And it’s even worse than it sounds; based on one Article in MIT Technology Reviewthe company has already started launching balloons into the stratosphere, though it hasn’t been able to determine if they’re actually deploying their payload.
Construct the stratosphere?
Geoengineering is generally defined as manipulating the environment in a way that alters the climate. Given this definition, our widespread burning of fossil fuels is a form of geoengineering. But with our ever-warming climate, most references to geoengineering now focus on ways to counteract that warming. Although a number of possible techniques have been considered, the most practical approach appears to be to throw reflective particles into the stratosphere to reduce the amount of sunlight Earth receives.
The general concept has already been validated by volcanoes, which send sulfur dioxide into the stratosphere and can trigger cooling in the years following an eruption. For example, the largest eruption of the last century (Mount Pinatubo) cooled the planet for about three years before the sulfur dioxide it carried into the stratosphere drifted down and then exited the atmosphere as rain.
Sulfur dioxide is cheap, and we have the technology needed to transport it to the stratosphere without erupting, so it could be an attractive alternative to the many expensive downstream effects of climate change. The “may” stems largely from the extensive unknowns associated with its pursuit. Everything from plants to solar panels depend on sunlight to reach the earth. And while we know the approach works, we still don’t know the details well enough to assign a specific cooling value for a specific amount of sulfur dioxide. This sulfur dioxide also forms sulfuric acid when exposed to water, which can lead to environmental impacts when used in the amounts required to alter the climate. Finally, reliance on geoengineering obliges us to continue doing so until atmospheric carbon returns to manageable levels.
For all these reasons, the scientific community was very hesitant about the idea. The National Academies report mentioned above suggests that there are so many unknowns that any research we do on geoengineering should be designed in a way that doesn’t make it any easier to go ahead and follow it. “Deliberate outdoor experiments that involve the release of substances into the atmosphere should only be considered if they can provide critical observations that cannot be provided by laboratory studies, modeling or casual experimentation — such as volcanic eruptions,” the report’s authors concluded . “Outdoor experiments should be subject to proper administration, including permitting and impact assessments.”
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