Hotter and Higher? Coca plants in a Changing Climate

When I was in my mid-20’s I traveled to Peru to visit my roommate from college who was working in Lima. She insisted that we travel into the Andes mountains to see one of the greatest works of mankind, Machu Picchu. To get there under 30 hours, we had to take a plane to Cuzco from Lima (just over an hour!) and then travel to the monument from there, but there is one hitch: Lima is at sea level and Cuzco is at 11,000 feet.

When the plane landed in Cuzco and they opened the cabin doors to the outside, we could literally feel the oxygen being sucked out of the cabin. The air was thin and quite frankly we didn’t last very long. By the time we had made it to the hotel, my friend had passed out and my head was throbbing in pain. I was so dizzy that when a 5.0 earthquake hit the city, I spent a good five minutes arguing with my friend as to whether it was really an earthquake or just the altitude sickness. By the time we made it outside, the earthquake was long past and people just stared at us wondering “Where the hell were you??” We had the altitude sickness and there was no cure. Or was there?

In Cuzco, as in many other high elevation locales in South America, there was one recommended treatment for altitude sickness: coca tea. And there is no question that it worked. Really well. A few sips relieved the stress in my head, allowed me to walk in a straight line and gave me the strength to lift my oxygen-deprived legs high enough to climb the stairs to our hotel room. It worked so well, that on my most recent trip to high elevation in India (complete with throbbing headaches and shallow breathing), I was deeply missing the tea.

So of course, when I returned, my mind turned to the science. How will coca plants adapt to climate change? In the years to come, will poor climbers like me have anything as reliable to give them relief from the dreaded altitude? And what about all the modern-day party kids reliving the highlights of the Go-Go 80’s – will they have to stick to reminiscing about Z cavariccis and un-ironic mullets, or will they be able to relive the less classy moments of Bright Lights, Big City?

The active ingredient in coca is an alkaloid (i.e. nitrogen containing compound) called benzoylmethylecgonine (say that 10 times fast – or just once, good luck!) Alkaloids are extremely common in plants, used as defensive compounds against insects, and they often have the added benefit of getting people buzzed (that cigarette you just smoked would have killed an aphid). You are no doubt familiar with the more legal (and even more beloved) varieties of alkaloids: nicotine, caffeine, morphine and codeine.

Published literature at the turn of the last century indicated that though the coca plants prosper in a variety of temperatures, alkaloid content is actually reduced by higher temperatures (1). Unfortunately, it was not clear in the literature what temperatures would induce the reduction or even what temperatures coca plants prefer – I think you need to be a Peruvian herbalist or drug lord to know these things for sure. From my literature search, it seems like the turn of century (before coca became a favored party drug) was the last time researchers looked into the alkaloid content of coca.

Fortunately hypotheses in science can be built on conjecture from similar organisms. So how is climate change going to affect alkaloid content in other plants? Well that is where it gets a little tricky – because it depends on the plant and it depends on the alkaloid. For example, though the beloved tobacco plant will grow larger in a high carbon dioxide environment (smokers everywhere cheer!), it will decrease its nicotine concentration – so dear smokers you may need to light up twice as much to get nearly the same buzz (2). Meanwhile the ever faithful poppy plant will increase both morphine and codeine in a higher carbon dioxide environment (3) – good news if you plan to get your wisdom teeth pulled in the next 100 years.

So what does this all mean? It means that not all plants or alkaloids are made equal, even if they are all nitrogen-containing compounds that people love to get buzzed on. If journeymen (and journey-ladies like me) want to know whether we’ll be able to seek relief in coca tea while hiking in high altitude in the future when the air is thick with carbon dioxide and a couple degrees warmer, we’ll just have to return to Machu Pichu in 100 years to see.

Minda Berbeco has a PhD in Biology from Tufts University and is a science blogger in the Bay area. As a former smoker, a caffeine junky, a lover of unblemished fruit and having had *all four* wisdom teeth taken out in one day, she is enamored with all of the joys and delights that alkaloids can bring to people’s lives. She plans to devote the next couple of blog posts to these excellent chemicals and climate change.

For your reading enjoyment:
(1) Peru: History of Coca
(2) Alterations in the production and concentration of selected alkaloids as a function of rising atmospheric carbon dioxide and air temperature: implications for ethno-pharmacology
(3) Recent and projected increases in atmospheric carbon dioxide and the potential impacts on growth and alkaloid production in wild poppy (Papaver setigerum DC.)

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