In the past three decades, the global average temperature has risen by 0.5 °C The accumulation of carbon in the atmosphere is observed as the biggest responsible for global warming. In the past thirty years, the amount of CO2 in the atmosphere has increased 15%. Therefore, governments and international organizations have focused on policies and regulations to cut emissions. However, emissions keep rising. Until today, there have been different methods to reduce emissions. Unless those methods will reduce emissions, what is plan B?
The sun-dimming technology can be the best answer to the previous question. A group of scientists from Harvard University launched solar geoengineering research, the Stratospheric Controlled Perturbation Experiment (SCoPEx), in 2017. The SCoPEx project aims to do experiments towards the development of Stratospheric Aerosol Injection (SAI). SAI seeks to mask the warming effects of greenhouse gasses instead of reducing emissions. SAI proposes to reflect sunlight back into space to reduce the world's warmth by spraying large amounts of small reflective particles high into the Earth's stratosphere. The primary researchers of the SCoPEx project who are Frank Keutsch and David Keith, announced that they are going to conduct the first part of the experiment in Sweden, and the test is scheduled for June 2021. Swedish Space Corporation is going to host the experiment in Kiruna, Northern Sweden.
The SCoPEx project has presently planned to release a cloud of 2 kilograms calcium carbonate – also known as chalk dust – into the stratosphere from a high-altitude balloon to study its effects on sunlight reaching Earth. Although sulfate aerosols might be the best choice for solar geoengineering by absorbing more heat, the SCoPEx project will spray the small plumes of calcium carbonate because it has less impact on the ozone. Scopex executives liken the release of calcium carbonate into the stratosphere to the ashes produced by volcanic eruptions. The Mount Tambora eruption in Indonesia in 1985 concluded with "year without a summer." In 1991, 20 million tonnes of sulfur dioxide released due to the eruption of Mount Pinatubo in the Philippines dropped the global average temperature by 0.5 °C.
When it comes to the financial burden of the sun-dimming technology, 3 million American dollars has been allocated only for the previously mentioned first test of SCoPEx. The billionaire founder of Microsoft, Bill Gates, and other private names are funding the sun-dimming technology developments of SCoPEx. The Harvard University Solar Geoengineering Research Program (SGRP) partially finances the SCoPEx project, and Bill Gates is an outstanding donor of SGRP. The SCoPEx project is also funded by the Fund for Innovative Climate and Energy Research (FICER), a fund for research grants and co-founded by Bill Gates. Last month, the National Academies of Sciences, Engineering, and Medicine (NASEM) also published a new report that urges the U.S. government to invest in sun-dimming technology research. According to the recent report of NASEM, solar geoengineering studies, including SAI experiments, should be financially backed by 100 and 200 million American dollars over five years by the U.S. government.
However, many scientists argue that sun-dimming technology can lead to inevitable adverse consequences, and Dr. Bill Hare is one of these scientists. Dr. Bill Hare argues that sun-dimming technology can be a hazardous technology and argues that it can be a dangerous interference with the climate system in many ways. A recent report by the Intergovernmental Panel on Climate Change (IPCC) has suggested that the sun-dimming project could reduce global temperatures by 1.5°C. However, this temperature decrease example brings many serious risks. As seen in the previous example of the 1815 Tambora Mount eruption, freezing temperatures caused crops to fail near-famine conditions.
Some scientists have mentioned releases from volcanic eruptions in Alaska and Mexico as potential causes of drought in the Sahel region of Africa. Therefore, this project may also cause significant deterioration of the global climate and undesirable consequences. Then, high-populated areas may be adversely affected, and this situation can cause another global refugee crisis. Dr. David Kaith is also aware of these concerns, and he has suggested establishing a risk pool for secondary disadvantages caused by sun-dimming technology.
Another concern is about exploiting this method by claiming against emission-free policies because sun-dimming technology mainly focused on reducing carbon in the atmosphere instead of cutting green gas or carbon emissions. According to Dr. David Keith, solar geoengineering is a supplement to cut emissions, not a substitute for cutting emissions.
Solar geoengineering is also complicated in the political field because deciding who can conduct this project will not be easy. According to Environment Editor of The Economist Catherine Brahic, all governments are needed on board to acquire global effect, which can be extremely difficult. When a state decides to use sun-dimming technology alone, this decision can impact specific regions or worldwide. Then, this situatiın can lead to intense international tension.
Theoretically, sun-dimming technology can cool the entire planet. The method is potentially straightforward because injecting a number of particles into the stratosphere is only need to do and there are several ways to execute it. However, some analysts and experts are concerned that this method could lead to different kinds of problems from climate to political. It will be the best choice to see the experiment results that will take place in June and follow the actions of the U.S. government, which has received a new proposal on this issue.