Stressed marijuana plants being grown outdoors across Northern California, assuming their growers are not stealing massive amounts of water, are likely to produce more potent pot this year as we enter our fourth consecutive summer of drought. This was an observation made by a retired USDA ethno-botanist James Duke to CBS 5 in a discussion about the overall effects on marijuana plants of both climate change and the drought. He says that when plants are under stress, they tend to exhibit more of their "medicinal qualities."

Also, climate change overall and rising CO2 levels in our air are contributing to outdoor pot plants that are both more potent, and require less water. This is according to a new piece in The Daily Climate.

"If you go back to the times plants evolved on land, the average CO2 (carbon dioxide) levels were 1,000 parts per million; today it's about 400," said Lewis Ziska, a plant physiologist with the U.S. Department of Agriculture’s Agricultural Research Service.
About 4 percent of plant species have adapted to lower CO2 levels, most of them subtropical grasses such as sorghum, corn and millet. However, most plants - including marijuana - still feel deprived of the optimal CO2 levels they were born into.13-ziska
Ziska's research suggests plants feeling deprived will benefit from rising CO2 levels because they haven't yet adapted to the lower levels. His own and other scientists’ work indicates the medicinal qualities of these plants may be bolstered by global warming.

So, in other words, start with one hit from here on out and see where you're at.

Also, that eighth might last a lot longer than it used to.

All previous coverage of marijuana on SFist.