Older Forests Boost Climate Cleaning Hydroxides (OH)

Runaway greenhouse gas emissions would be far worse if it wasn’t for the wonderful atmospheric molecule OH:

“It initiates the reactions that break down airborne pollutants and helps to remove noxious chemicals such as sulfur dioxide and nitric oxide, which are poisonous gases, from the atmosphere,” said Christian George, an atmospheric chemist at the University of Lyon in France and lead author of the new study.” https://www.technologynetworks.com/tn/news/light-shed-on-how-the-atmosphere-cleans-itself-371948

It has long been thought that OH can only be produced from a catalyst of sunlight or from transition metals, like Nickel (Ni). But a recent paper published has discovered that OH can be produced without sunlight and without transition metals by way of the electrical field on the surface of raindrops:

The team measured OH concentrations in different vials – some containing an air-water surface and others containing only water without any air – and tracked OH production in darkness by including a “probe” molecule in the vials that fluoresces when it reacts with OH.

What they saw is that OH production rates in darkness mirror those and even exceed rates from drivers like sunlight exposure. “Enough of OH will be created to compete with other known OH sources,” said Nizkorodov. “At night, when there is no photochemistry, OH is still produced and it is produced at a higher rate than would otherwise happen.” ibid

This means that when the sun comes out on young forests and the moisture quickly evaporates there is less OH production. But in the dense shade of closed canopy forests with large old trees the massive amount of water held in the canopy dries out slower and even turns into rainfall again by way of gravity or by prevailing winds which carry that rainfall back into sky and further inland via Ekman spirals.

Theories connecting forests with rainfall peaked in popularity in the 1850s to 1880s, a period when scientists expressed alarm that deforestation caused regional declines in precipitation. Forests were understood to create rain within a locality and region. Scientific consensus shifted by the early twentieth century to the view that forests did not play a significant role in determining rainfall. The forest-rainfall connection reemerged in the 1980s alongside advances in climate modelling and growing fears of anthropogenic global warming and tropical deforestation. Using new data and theories, supply-side advocates have once again placed a strong forest-rainfall connection into scientific prominence. https://forestecosyst.springeropen.com/articles/10.1186/s40663-017-0124-9

While a great deal more research needs to be done when it comes to measuring OH production from forests, this new research puts it on the table for further study.

This could be especially relevant in coastal forests during the dry season where Dr. Rudy Becking RFPF-00 did studies to show fog gathered from the leaves and branches of giant trees can consistently produce a 1/2 foot of annual dry season rainfall in coastal Redwoods and coastal Eucalyptus forests.

The needle-shaped leaves of conifers are efficient fog droplet collectors, and fog drip in mountainous regions may supply enough water to maintain forests.” https://www.britannica.com/science/fog-drip