It sounds like rhetoric from the tinfoil-hat chemtrail conspiracy community. Large commercial airliners spraying sulfate microparticles into the stratosphere, anywhere from 8 to 30 miles high. The purpose is to help shield the Earth from sunlight to maintain lower temperatures.
The report is one of the most in-depth and modern study yet of "stratospheric aerosol injection"(also known as "solar dimming" or "solar engineering" and or in the conspiracy community - "chemtrails"). Researchers examined how effective and expensive a solar geoengineering project would be beginning in the early 2030s. The goal of the program would be to halve the temperature increase caused by heat-trapping greenhouse gases, sort of like the global cooling effects of volcanic eruptions.
Gernot Wagner, a research associate at Harvard’s School of Engineering and Applied Sciences, is the lead author of the paper. He said their study shows this type of geoengineering "would be technically possible strictly from an engineering perspective. It would also be remarkably inexpensive, at an average of around $2 to $2.5 billion per year over the first 15 years."
The study's co-author of the paper and lecturer at Yale, Wake Smith, explained that an entirely new aircraft needs to be designed for the chemtrail program. "No existing aircraft has the combination of altitude and payload capabilities required."
Researchers investigated what it would cost to develop an aircraft they call he SAI Lofter (SAIL). The report indicates the fuselage would have a stubby design and the wing area, as well as the thrust, would need to be twice as large. The estimated cost of the plane, a whopping $2 billion and $350 million to modify existing engines.
The American Meteorological Society (AMS) expressed great concern about the project, which said, "reflecting sunlight would likely reduce Earth's average temperature but could also change global circulation patterns with potentially serious consequences such as changing storm tracks and precipitation patterns."
In other words, screwing with the mother nature might have unintended consequences and likely trigger a new set of problems.
This report should undoubtedly cause discussion in the chemtrail conspiracy community.