TBI - 'Tea Bag Index' - Becoming a Climate Change Metric

For the price of a cup of tea, or perhaps several, we are making strides towards better understanding climate change thanks to Judith Sarneel, a researcher at Umeå University in Sweden, and her colleagues: Joost Keuskamp, Bas Dingemans, Taru Lehtinen, and Mariet Hefting. Sarneel developed the Tea Bag Index—a simple and reliable way to figure out the speed at which decomposition occurs. The Tea Bag Index is now being rolled out in a massive, global citizen science campaign with the goal to strengthen our understanding of global decomposition patterns and better inform climate models.

So how does it work? Tea bags are weighed, buried in the soil, dug up after 90 days, and then reweighed. The amount of mass loss during the time the tea bag is buried is divided by the duration of time the tea bag is buried which gives us the decomposition rate—a normalized value of mass lost per unit of time (e.g. grams per day). Decomposition rates vary globally, from incredibly rapid rates in warm, humid areas such as the tropics, to glacially slow rates in the Arctic.


Ozzy Delaney