Cloud seeding usually results in the release of precipitation into parched regions of land. However, a discovery made about a natural version of the process reveals a surprising fact about the climate. The formation of clouds may be aided by a chemical produced by trees. A pair of experiments showed that molecules released by trees are capable of seeding clouds.
If these studies are confirmed, then skies in the pre-industrial world may have been significantly cloudier than previously believed. This would also mean that climate studies have underestimated the role played by clouds on the environment prior to the Industrial Revolution.
The development of certain cloud formations were once thought to be dependent on the introduction of sulfuric acid into the atmosphere. These latest experiments seem to refute this idea. This acid is produced, along with carbon dioxide, during the combustion of fossil fuels. The chemical is known to have the ability to seed clouds, an effect which is normally factored into historical records used in developing climate models.
“So, climate scientists have assumed that since pre-industrial times, there has been a large increase in cloud cover, which is thought to have an overall cooling effect by reflecting sunlight back into space. And they have assumed that this overall cooling effect has partially masked the climate’s underlying sensitivity to rising carbon dioxide levels,” Davide Castelvecchi writes for Nature.
Clouds are largely composed of ice crystals or tiny particles of liquid water. However, this moisture needs a nucleus around which to condense in order to form clouds. These aerosols come from a wide range of sources found on land, water, and in the atmosphere.
If skies were significantly cloudier during the pre-industrial era than commonly assumed, then the masking effect of the phenomenon is greater than normally measured. This would mean that global warming since the start of the Industrial Age has not been as severe as commonly measured.