In the continuous effort to counteract global warming, scientists have been devising technologically advanced ways to cool the planet.  An analysis published October 26 that examines the wildest idea they have ever considered; spraying tiny diamond particles high in the atmosphere to cool the earth.

As reported in Nature, scientists have argued for years the effects of pumping water-based sulphate spray over the Earth to reflect and scatter the Sun's energy.  This process is mimicking the cooling caused by volcanic eruptions.  However this idea is highly controversial as most geoengineering concepts go and never been tested.

Now if anyone did try the "solar-radiation management" proposition, scientists argue that it would be safer to use dusts of solid, nanometre-sized particles instead.  A team of scientists from Harvard University in Cambridge, Massachusetts has published an article in Atmospheric Chemistry and Physics, discussing the merits of spraying nanoparticles of diamond or alumina (aluminium oxide).  They calculated that this process is more effective and less damaging to the environment.

An atmospheric modelling expert at Harvard and one of the proponents of the study, Debra Weisenstein said, "Our paper is really geared towards removing the mindset that it has to be sulphate that's used to do solar radiation management".

Previous studies have proposed spraying solid dusts before however sulphates may lead to the production of sulphuric acid which can damage the ozone layer.  Another effect noted is the possible heating of the lower stratosphere that could affect air circulation patterns and climate.  Although sulphates may boost plant growth, it can lower the power output of solar panels.

However, alumina and diamond dust have fewer problems according to Weisenstein, "You could have significantly less impact on ozone, less heating of the stratosphere and less of an increase in diffuse light at Earth's surface".

These particles absorb particular wavelengths of light in a different way and do not result in the production of sulphuric acid.  More so, diamond dust is less expensive than cut gemstones.  However, the study states that it would take hundreds of thousands of tonnes of dust annually to counteract greenhouse gasses.

"Once this can be scaled up to make the right quantities, you assume the price is going to drop," she says. "Trying to estimate based on how much diamond costs currently are not particularly useful."

However, scientists warn of unknown risks compared to sulphates which are reasonable well understood.  The Harvard scientists are doing lab tests to further understand the chemistry of these solid particles.  This alternative way of cooling off the planet may be less popular compared to sulphate sprays however this is a remarkable breakthrough with science.