Our sun showers our earth with electromagnetic radiation (light) of all varieties all the time – some of it is mild in intensity and some of it is very strong in intensity. The light that is stronger in intensity, such as ultra violet and even higher frequency light, starts to become dangerous to biological life. You and I can avoid damage to our bodies from high frequency light radiation, such as UV, by wearing long sleeve shirts and pants or by using sunscreen.
Plants need lots of sun exposure in order to produce the food they will use, but like us, UV and other higher frequency light, is biologically dangerous to them. How do they avoid getting sun burned, or in other words, being damaged by high frequency light? Plants obviously don’t wear clothes or put on sunscreen like we do. But plants actually do manufacture their own sunscreens and use them to shield themselves from dangerous and prolonged exposure to dangerous light.
Plant-manufactured sunscreens are quite a bit different than the sunscreens we buy in a bottle at the store. Plant sunscreen is actually a carbon based gaseous molecule that the plant excretes out of its leaves that simply hovers over the plant and absorbs UV and other higher frequency light while allowing the beneficial light to pass straight through and be used by the plant.
For the more technical reader: this gaseous sunscreen is an organic compound; a type of isoprene. For deciduous trees a commonly used isoprene for UV shielding is 2-methyl-1,3-butadiene; conifers excrete α- and β-pinene. This excretion is what creates the blue-ish haze commonly seen over a forest on a calm sunny day. These gaseous plant sunscreens, as well as other isoprene UV absorbers, account for hundreds of millions of tons of gaseous atmospheric carbon emissions per year world wide. But it is all natural and absolutely necessary for the survival of plants, as well as humans, because we rely on plants for all our food in some way or another.
