Warming World, Potent Poppies

Greater concentrations of carbon dioxide in a warming world may have a drastic effect on the potency of opium poppies, according to a new study. While this increase might mean more morphine available for legal pharmaceutical uses, the painkiller is also the main ingredient in heroin.

The current crop of poppies is twice as potent as those grown at carbon dioxide levels seen in 1950, says Lewis Ziska of the U.S. Department of Agriculture’s Crop Systems and Global Change Laboratory. If projections hold, the rise in atmospheric carbon dioxide will increase morphine levels three-fold by 2050 and by 4.5 times by 2090.

“I was surprised to see that the alkaloid levels changed so quickly,” says Ziska. Morphine is part of a class of chemicals called alkaloids, which plants produce to ward off bugs, birds and other natural dangers. While toxic to some animals, humans use hundreds of plant alkaloids in various ways. Cocaine, caffeine, capsaicin (which makes chili peppers hot), lysergic acid (a precursor for LSD) and the anti-malarial drug quinine are all examples of alkaloids.

The speed of the biological changes affecting plants’ alkaloid levels suggests that the climate may have a greater impact on plant life than computer models had generally predicted, Ziska says. Earlier studies by Ziska had shown that certain alkaloids decrease in some plants as carbon dioxide increases, including lower concentrations of nicotine in tobacco.

The net result, according to Ziska, is that climate change’s impacts on plants are likely to be chaotic and difficult to predict. For example, he says, “wheat may make more seeds, but we may have stronger poison ivy and poppies.”

Changes in alkaloid levels may pose a challenge to public health as carbon dioxide continues to build up in the atmosphere. The World Health Organization estimates that over 3.5 billion people rely on plants for part of their primary health care. This includes the U.S. population, where 25 percent of prescribed drugs contain an ingredient derived from plants.

Ziska’s research illustrates just how little we know about the biological effects of climate change. While predictions of increased drought and insect infestations in a warmer world are bad news for plants, the carbon-enriched atmosphere would give them more fuel to burn, helping many species grow bigger and produce more seeds. Meanwhile, a secondary set of chemical reactions not related to plant growth may also be influenced by levels of atmospheric carbon. These reactions create many of the chemicals used in medicines and are so complex that, for many plants, says Ziska, “we don’t have any idea how climate change will affect them.”

To learn what global warming would mean for some plants important to the pharmaceutical industry, Ziska, in conjunction with the U.S. Drug Enforcement Agency, grew the wild poppy, Papaver setigerum, inside growth chambers from seeds to mature plants. Resembling large stainless steel refrigerators, the chambers are sealed environments in which researchers can carefully control the light intensity, temperature, humidity and carbon dioxide concentration.

Once the poppies were ready for opium harvesting, researchers used a razor blade to score the bulbous capsules at the base of each flower and collected the excretions for analysis. When a poppy is cut it excretes a white sticky substance similar to a rubber plant or milkweed. This substance is the opium gum, which can be dried and smoked or refined into pure morphine, codeine or other drugs.