By presenting their findings via a sophisticated computer model, the scientists have shown that a new approach to geoengineering could possibly be used to lessen the Earth's warming while reducing some of the risks that have been posited in previous studies, such as the uneven cooling of the globe.
Geoengineering, which is also called climate intervention, is the process of interfering with the Earth's climatic system with the intention of reversing global warming. ("Geoengineering" is sometimes used interchangeably with the term "chemtrails.")
Past studies tried to answer the age-old question “What happens if we do geoengineering?” The studies showed both positive and negative outcomes but they were not able to specify the outcome they hoped to achieve at the outset.
Today, the researchers are now seeking the answer to the question, “How might geoengineering be used to meet specific climate objectives?”
“We have really shifted the question, and by doing so, found that we can better understand what geoengineering may be able to achieve,” NCAR scientist Yaga Richter, one of the lead authors, says.
Geoengineering can be accomplished in many ways, from launching orbiting solar mirrors to fertilizing carbon-hungry ocean algae. For this experiment, the scientists have analyzed a much-discussed approach: injecting sulfur dioxide to the upper atmosphere, above the cloud layer.
The idea of fighting global warming with these injections is taken from history's biggest volcanic eruptions. Volcanic eruptions cause sulfur dioxide to burst high into the atmosphere, where it is chemically transformed into light-scattering sulfate particles called aerosols.
These aerosols, which stay in the atmosphere for a few years, envelop the Earth with the help of stratospheric winds, creating a reflective layer that cools the planet.
Copying the after-effects of a volcanic eruption can be done by injecting sulfur dioxide directly into the stratosphere. However, while the injections would address global warming, they would not solve all the problems associated with climate change, and they would most probably have their own negative side effects.
These negative side effects include extreme interference in rainfall activity as well as delays in healing the ozone hole. Furthermore, once geoengineering started, if people do not want to experience a significant increase in temperature, the injections would need to continue until mitigation efforts were enough to cap warming on their own.
The scientists have utilized the NCAR-based Community Earth System Model with its extended atmospheric component, the Whole Atmosphere Community Climate Model (WACCM). WACCM features a proper outline of the upper atmosphere and just recently has showcased how stratospheric aerosol evolves from source gases, including geoengineering.
“It was critical for this study that our model be able to accurately capture the chemistry in the atmosphere so we could understand how quickly sulfur dioxide would be converted into aerosols and how long those aerosols would stick around. Most global climate models do not include this interactive atmospheric chemistry,” NCAR scientist Michael Mills, also a lead author, said.
The scientists have tested their model by looking at how well it could simulate the cataclysmic 1991 eruption of Mount Pinatubo in Central Luzon in the Philippines, including the amount and rate of aerosol formation, as well as how those aerosols were scattered around the globe, and how long they lingered in the atmosphere.
After that, the scientists have explored the impacts of injecting sulfur dioxide at different latitudes and altitudes. The scientists already have knowledge that sulfates that were injected only at the equator affect Earth unevenly: over-cooling the tropics and under-cooling the poles. This is problematic because climate change is warming the Arctic at a fast rate, and the Northern Hemisphere is warming up faster than the Southern Hemisphere.
The scientists were able to come up with 14 possible injection sites at seven different latitudes and two different altitudes; choosing injection sites on either side of the equator could spread the cooling more evenly. (Related: Global warming computer models collapse; Arctic ice sheets rapidly expand as planet plunges into global cooling)
The researchers then collated all their findings and put them into a single model simulation with specific objectives such as limiting average global warming to 2020 levels through the end of the century and minimizing the difference in cooling between the equator and the poles and between the northern and southern hemispheres.
A caveat: The amount of sulfur dioxide that would need to be injected each year to offset human-caused global warming at the end of the century would be five times the amount thrown into the air by Mount Pinatubo on June 15, 1991.
The same scientists are currently working on determining the possible impacts that geoengineering might have on regional phenomena, such as Asian monsoons. “Continuing research into geoengineering is critical to assess benefits and side effects and to inform decision makers and society,” NCAR scientist and lead author Simone Tilmes says.
'Marine cloud brightening' as a way to counter global warming
Some scientists want to explore the possibility of countering the impacts of climate change via “marine cloud brightening”, a process that looks at seeding marine clouds with salt water or other particles to increase the ability of clouds to reflect solar energy away form the Earth's surface, thereby dropping temperatures caused by global warming.
“We think SRM [sunlight reflection methods] could buy time for other [carbon-reduction] measures to be put in place,” PNNL chief climate scientist Philip J. Rasch told the House of Representatives committee on science, space, and technology on Wednesday, November 8.
Republicans in the House are interested in such new technologies to reduce the effects of climate change so as to shift the current trend of imposing regulations on industries, particularly oil companies and producers of fossil fuels.
“As climate continues to change, geoengineering could be a tool to curb resulting impacts. Instead of forcing unworkable and costly government mandates on the American people, we should look to technology and innovation to lead the way to address climate change,” said House committee on science, space, and technology chairman Lamar Seeligson Smith (Republican from Texas).
For more interesting stories regarding climate change, its impacts, and how various government agencies are trying to come up with solutions to address the problem, visit ClimateScienceNews.com.
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