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World’s supply of frankincense could go up in smoke

Frankincense, one of three fabled gifts the wise men brought to honor Jesus, has been used for millennia as an incense in cooking and religious ceremonies. In Catholic churches today, the tendrils of smoke rising from burning frankincense are thought to carry prayers toward the heavens. Now, the earthy smell that evokes memories of spiritual communion for so many is under threat: Human activity is predicted to cause a 50% decline in frankincense harvests over the next 20 years, according to new research.

Frankincense is made from the milky sap of trees in the Boswelia genus, found mainly in wild trees in Africa and India. People harvest the sap by gouging the bark of wild trees; they then dry it into golden yellow grains, which can be burned or blended into other fragrances. But growing anecdotal evidence suggested the trees were threatened by overexploitation and growing populations.

To gauge the apparent threat, scientists assessed 21,786 Boswelia trees across 23 different sites in East Africa and estimated their ages by analyzing the growth rings of 202 trees. Then, they created computer models that project the trees’ future populations. Their models predict that the population of frankincense-producing trees will drop by 50% in the next 15 years, they report today in Nature Sustainability. The researchers also estimate that the world’s supply of frankincense would be cut in half in 20 years, if current trends continue. 

Increased pressure from growing human populations and overexploitation are the main culprits—in particular, livestock that roam the forest and snack on saplings before they’re able to reach adulthood. Brushfires set by farmers often incinerate what the cattle miss. Full-grown Boswelia trees are also killed by overharvesting, which bleeds them dry or makes them vulnerable to deadly pests and disease.

Scientists say the frankincense crisis could still be averted—by fencing off key forests to protect them from livestock, establishing fire-breaks, and enforcing more conservative guidelines for sap extraction. If that doesn’t work, the faithful may want to start praying.