Scientists are ready to send aerosol injections 20 kilometres (12.4 miles) up into the stratosphere to assess the technique's feasibility as a technical fix for global warming.

The purpose is to safely simulate the atmospheric cooling effects of a large volcanic eruption. The US$20 million Harvard University project is the world's largest solar geoengineering program ever, and it will launch within the next few weeks.

The scientists behind the project intend to complete two small-scale dispersals by 2022. The first will disperse water into the stratosphere, and the second will disperse calcium carbonate particles.

In the future, tests may include seeding the upper atmosphere with aluminium oxide or even the more exotic option: diamonds.

These techniques mimic the natural alterations to Earth's normal radiation balance seen after large-scale volcanic eruptions.

The 1991 eruption of Mount Pinatubo, for example, lowered global temperatures by 0.5°C (.9°F).

On the other hand, the 1815 eruption of Mount Tambora cooled Earth with more sinister results - disease, crop failure, and famine followed Europe's "year without a summer" caused by that eruption.

Indeed, a 2013 Met Office study warned that dispersing fine particles in the stratosphere could cause a disastrous drought in North Africa.

This unpredictable and possibly dangerous range of results is just one of the reasons the program is being met with opposition from within the scientific community. Unproven technical fixes should not take the focus away from mitigation efforts with proven results, but some critics fear that they might.

"[S]olar geoengineering is not the answer," Kevin Trenberth, a lead author for the United Nation's intergovernmental panel on climate changetold The Guardian.

"Cutting incoming solar radiation affects the weather and hydrological cycle. It promotes drought. It destabilises things and could cause wars. The side effects are many, and our models are just not good enough to predict the outcomes."

Countries like China have been working hard to cut down on emissions and adopt clean energy solutions.

And while official US policy appears to now omit any discussion of climate change - if not deny human-driven climate change outright - a team of elite tech leaders in the US is investing extensively in climate solutions with the goal of reducing emissions.

The state of California is also continuing its work in emissions reduction, leading the rest of the US in those efforts.

Even the scientists running the Harvard program acknowledge that geoengineering must be seen as a complement rather than a substitute for aggressive reduction of emissions.

Still, they assert that it is essential that we know how geoengineering might work in case we should ever need to deploy it.

Frank Keutsch, the atmospheric sciences professor leading the experiment, calls the deployment of a solar geoengineering system "a terrifying prospect".

However, he adds, "At the same time, we should never choose ignorance over knowledge in a situation like this."

This article was originally published by Futurism. Read the original article.