By now, you have certainly heard of the detrimental effect of global warming; let us be honest, it is a problem that touches all of us. However, researchers have found numerous sustainable ways to manage this environmental crisis, one of which includes a solar geo-engineering method - Marine Cloud Brightening (MCB). What is Marine Cloud Brightening? The aim of this geo-engraving method is to make clouds whiter in order to reflect more sunlight back into space. By increasing the concentration of smaller cloud droplets, the brightness of the clouds can be increased. To accomplish this, MCB supporters propose bombarding marine clouds with copious quantities of small particles, including sea salt aerosols. These particles would serve as condensation nuclei for the formation of microscopic cloud droplets by acting as centres for the condensation of water vapor. However, how will these particles get to the clouds? According to current plans, seawater sprayed from ships equipped with nozzles that can break up saltwater into tiny particles would be used to inject salty aerosols into maritime cloud layers. In theory, brighter clouds might reduce the amount of solar radiation that reaches the surface of the Earth; this would lower the temperature of the atmosphere and seas since they would absorb less solar energy. This vision is summarised by Harvard University’s David Keith's research group: “The most common proposal for achieving such a goal is to inject naturally occurring sea salt into cloud updrafts. But a variety of methods are being researched. The Keith Group believes that marine cloud brightening research is valuable. It can teach us a great deal about the ways in which clouds can and do affect our climate. However, our group does not focus on this particular research because current marine cloud brightening proposals carry several key risks.” (Fig.1) One of the risks is that MCB, like all solar geo-engineering methods, might alter weather patterns; the alteration of which may result in disastrous ecological effects on entire regions and it would not lower the amount of greenhouse gases in the atmosphere. Despite the potential of this method, a question arises - who would decide where droughts or floods brought on by widespread cloud brightening would occur? What are the risks this potential method is bringing to the table? Even if marine cloud brightening were to be effective enough to achieve a level of "radiative forcing" that would be sufficient to counteract some of the most significant effects of climate change, - it could have an affect on altering the weather patterns, if it were used on a large enough scale. This is because marine cloud brightening could only be used in specific regions where the appropriate types of clouds are present, which is likely only 10% of the planet's surface. Moreover, there are several significant hazards of the technology that require further clarification. Nevertheless, although all geo-engineering methods that more study is required, especially MCB, such revolutionary methods could help resolve the climate change crisis and aid with the development of the geo-engineering field.
Bibliography:
Latham, et al. (2012) Marine Cloud Brightening, in Wood, et al. (2017) Could spraying particles into marine clouds help cool the planet?, in Philosophical transactions, Series A, Mathematical, physical, and engineering sciences, Vol. 370: 4217 - 4262, https://doi.org/10.1098/rsta.2012.0086; University of Washington News, published: July 25, 2017, https://www.washington.edu/news/2017/07/25/could-spraying-particles-into-marine-clouds-help-cool-the-planet/
Rosen (2020) How will geoengineering aerosols affect air temperature?, in: Geoengineering Monitor, published: September 16, 2020, http://www.geoengineeringmonitor.org/2020/09/how-will-geoengineering-aerosols-affect-airtemperature/; ETC Group and Heinrich Böll Foundation (2020) https://keith.seas.harvard.edu/marine-cloud-brightening