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How Will Climate Change Affect Cannabis?

A report by the International Panel on Climate Change (IPCC) suggests that we are fast approaching a global crisis. Such an outcome is sure to have significant repercussions for us all.

However, several studies have suggested that cannabis may thrive as a result of climate change. Decreased rainfall, higher temperatures, and increased levels of carbon dioxide in the air can dramatically affect the growth of plants and may result in higher yields of cannabinoids.

Could Climate Change Lead To Stronger Cannabis?

Cannabinoids like tetrahydrocannabinol (THC) and cannabidiol (CBD) help protect cannabis plants from various environmental threats. Over the years, growers have developed numerous stress techniques that cause plants to increase their production of these desirable compounds.

Climate change will undoubtedly heap extra stress on cannabis plants and could therefore result in higher cannabinoid yields.

To test this theory, researchers recently investigated the impact of drought on cannabis. While growing a cultivar that typically produces 5.66 percent THC and 10.3 percent CBD, the study authors withheld water for around 11 days during the flowering phase, causing plant water potential levels to drop significantly.

Tetrahydrocannabinol acid (THCA) concentration subsequently rose by 12 percent, while cannabidiolic acid (CBDA) concentration increased by 13 percent in these drought-stressed plants.

Flower size also increased, meaning that overall THC yields were 50 percent higher than in plants that received ample water, while CBD yields were 67 percent higher.

Obviously, extended droughts are harmful to all plants, so it’s impossible to say whether climate change will benefit cannabis in this way. However, this study provides some fascinating insights into the possible impact of future droughts on cannabis plants.

The Contradictory Effects Of Climate Change On Cannabis

In all likelihood, the consequences of climate change will be a mixed bag for cannabis. This was highlighted by a 2009 study that found that extreme temperatures may hinder photosynthesis, but rising carbon dioxide levels could have the opposite effect.

The researchers measured the rate of photosynthesis and water user efficiency in cannabis plants at a range of temperatures. Results indicated both of these increased with temperature but hit a peak at 30 degrees Celsius. Beyond this point, both photosynthesis and water use efficiency dropped off. Suggesting that extreme temperatures brought about by climate change could be bad news for cannabis.

At the same time, the study authors measured the impact of carbon dioxide concentration on photosynthesis. Carbon emissions are the leading cause of climate change and are resulting in higher concentrations of carbon dioxide in the air. This is likely to benefit many plant species, as carbon dioxide is a vital ingredient for photosynthesis.

Current ambient carbon dioxide levels are around 350 micromoles per cubic metre of air (μmol mol(-1)). Yet, the researchers found that photosynthesis increased by 50 percent when carbon dioxide levels were raised to 750 μmol mol(-1).

Two years later, the same researchers conducted a more detailed study on the effect of carbon dioxide on cannabis plants. Using 4 different high-THC cultivars, they found that photosynthesis increased by up to 48% when carbon dioxide levels were 700 μmol mol(-1). Water use efficiency, meanwhile, rose by up to 191 percent.

Overall, it’s hard to predict exactly what climate change will mean for cannabis, although ideally, we’d rather not find out.

Cultivation information, and media is given for those of our clients who live in countries where cannabis cultivation is decriminalised or legal, or to those that operate within a licensed model. We encourage all readers to be aware of their local laws and to ensure they do not break them.

This post is also available in: French

Ben Taub