‘Lung’ tests for the Amazon: A new study is measuring carbon intake, plant by plant

The findings could help climate scientists fine-tune their prediction models. And they could raise the rates at which carbon credits are sold.

Is the Amazon rainforest a carbon sink or a carbon source? Has it tipped over, and when?

The Amazon rainforest was one of the world’s largest carbon absorbers. It still releases 20 billion tonnes of water into the atmosphere a day, playing a crucial role in weather, carbon and water cycles. (Adobe Stock)

The health of Earth’s “green lung” has long been recognised as a key parameter of the overall sustainability of the planet (for human habitation; lots of other life forms will likely continue undisturbed).

The Amazon was traditionally one of the world’s largest carbon absorbers. It still releases 20 billion tonnes of water into the atmosphere a day, playing a crucial role in global weather, carbon and water cycles.

But, for decades, fires lit to clear land for cash-crop cultivation, cattle ranches, logging, mining and infrastructure development have pushed this rainforest right to the edge (in some opinions), and over the edge (in others).

Now, scientists are rather bravely attempting to face the truth of where we stand on this vital front, by gathering granular data on the “lungs” themselves.

The plan is to collect micro-measurements of patches of the rainforest in Colombia and Brazil, and use this data to extrapolate the state of health of the Amazon’s total area of about 6 million sq km (roughly twice the size of India).

How minute will the measurements be?

The research project is led by the Smithsonian Tropical Research Institute (STRI), Panama, incidentally the Smithsonian Institution’s only bureau outside the US, and is set to begin with a study of a 2.5 lakh sq metre segment of Colombia’s Amacayacu National Park.

Here, researchers will first conduct a census of every “plant” (defined as anything with a main stem diameter of 1 cm or more). They will then collect and measure leaves from branches at different levels of each plant, and use this data to estimate how much carbon it likely absorbs.

Since Amacayacu is an extremely biodiverse region, the findings can serve as representative of the northwestern Amazon overall, says Alvaro Duque, 59, a professor of forest sciences at National University of Colombia, which is collaborating with STRI on the project.

There are plans to replicate this method at rainforests around the world, with 30 such studies planned overall, including in Brazil, where 60% of Amazon lies.

The alternative, for the Amazon, has been to rely on aerial and satellite imagery, which cannot really penetrate the forest’s thick canopy, Duque says. “This study could have effects that are big and far-reaching,” he adds.

What could it change? Given the global implications of the state of this green lung, the findings could, for one thing, help climate scientists update and fine-tune prediction models. For another, it could alter the rates at which carbon credits are traded around the world, making credits more expensive, and therefore more lucrative a product to sell.

Meanwhile, the clock is ticking. This year alone, forest fires in the Brazilian Amazon hit and then exceeded a 14-year high, burning through an area at least the size of Italy.