By Evan Lund
After President Donald Trump's first 100 days in office, the guiding principle behind his policy directives has become abundantly clear: Shield the United States from outside dangers -- both foreign and domestic. As he prepares for a funding showdown over the construction of his infamous border wall, it's apparent that such "shielding" strategies are integral to this administration's desire to protect its people.
In the interest of protecting Americans, it is likely that President Trump might even start to recognize global climate change as a threat. While it's far from the consensus opinion of their party, Republicans in Congress have slowly started to publicly acknowledge the dangers of climate change. However, they also believe President Barack Obama's Clean Power Plan is overly complicated and unrealistic, and they argue that climate change strategy shouldn't necessarily involve increasing regulation.
Considering the Trump administration's deep ties to the fossil fuel industry and the uncertainty of whether or not the U.S. will be able to meet its emissions reduction goals as outlined in the Paris climate accord, it isn't surprising that alternative options are on the table. The option most frequently championed is solar geo-engineering.
Republicans have long touted technologies that harbor the potential to alter the planet's climate system as the best option to reduce global warming. Solar geo-engineering hinges on enhancing Earth's albedo: the amount of solar radiation that reflects off the surface. If adopted, the method would involve injecting metric tons of materials into the atmosphere that could serve as mini-shade devices or nucleation hubs for artificial cloud creation. The result: more reflective clouds, more protective cover, and less incident radiation reaching the ground.
Sulfate particles are one of the many materials that could theoretically perform the job. Phytoplankton and volcanic eruptions naturally produce sulfate aerosols, and these particles can serve as a substrate on which water vapor can condense into clouds that reflect solar radiation.
The best features of geo-engineering are its relatively low cost and immediate temperature-reducing effects. Geo-engineering technologies are estimated to cost only $2 billion to $10 billion a year, low enough for most middle-income countries to afford. Compared to the estimated $200 billion to $2 trillion annual cost of implementing fossil fuel mitigation strategies, the technology offers decreased global warming at 1 percent of the total cost of systemic emissions reduction.
Despite the potential advantages, significant knowledge gaps remain for what could happen if we intentionally manipulate the planet's climate system. Potentially a benefit, the use of aerosols would alter temperatures immediately and only impact the regions where the technology is deployed. However, there are concerns that cooling temperatures in one area of the world may have unpredictable consequences elsewhere, disproportionately affecting regions most vulnerable to extreme weather events. For example, as the Guardian reported, modeling has shown that stratospheric spraying would drastically alter global rainfall, likely causing severe droughts that would threaten the food supply for billions in areas throughout Asia, Africa and South America.
Furthermore, geo-engineering is only a preventative measure -- it reverses none of the pre-existing damage attributable to climate change. Since it has no effect on current greenhouse gas levels, the technique offers no solution to related issues like carbon dioxide elimination or ocean acidification.
But what it might buy us is time, and considering that our current understanding of tipping points reflects an associated risk with rising temperatures, the method should be properly investigated as a legitimate part of our overall strategy.
Recently, the U.S. Global Change Research Program, a consortium of 13 federal agencies involved in climate research, released a report advocating geo-engineering studies be designed to examine the risks and benefits of its large-scale implementation, for the first time ever. Also, a multi-disciplinary team of Harvard researchers is working toward a 2022 field study of the technology. David Keith, a Harvard physicist involved in the study, is quick to defend the science, but also considerate of those who are afraid that the political benefits of solar geo-engineering could outweigh the planetary costs.
Since researchers investigating the technology regard the approach as a supplement, not a substitute, to ongoing climate change measures, some are afraid that President Trump could offer geo-engineering as a short-term solution for our warming planet while shirking our global responsibilities to curb fossil fuel usage. What we must keep in mind is that last year was the warmest year on record and atmospheric carbon dioxide levels are higher today than at any point in the last 3 million years. Let's hope this expanded "shielding" research introduces another viable tool to add to our climate change arsenal for the long run instead of just the cost-effective solution for right now.
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