ESA investigates high-stakes Amazon tipping point

The Committee on Earth Observing Satellites has identified the Amazon region as a potential near-future tipping point – a ‘point of no return’ – for global greenhouse gas emissions, warning that parts of the rainforest may soon shift from absorbing carbon to becoming a net source of carbon.

Yet significant uncertainty still surrounds current greenhouse gas fluxes and how these could change in the future.

The ESA large-scale field campaign, called the Carbon Amazon Rainforest Activity aims to plug this knowledge gap.

The campaign involves researchers collecting a suite of measurements from the ground-based sensors, towers, drones, and even from a low-flying aircraft skimming the forest canopy – all to better understand how greenhouse gases move through this vital ecosystem.

By combining these measurements with a range of satellite data, the team will deliver a comprehensive set of multiscale measurements to strengthen understanding of greenhouse gas emission trends from natural sources.

This work represents a major contribution to the global stocktake and to international efforts to limit warming in line with the Paris Agreement.

Since September, European and Brazilian scientists – led by King’s College London and the UK’s National Centre for Earth Observation – have concentrated their efforts on a 100 km by 100 km area in western Pará State, Brazil.

It is feared that this zone, which includes undisturbed forest, farmland and degraded land, is already tipping from a carbon sink to a carbon source, making it an ideal testbed for understanding the impacts of deforestation, degradation and fire on the Amazon’s ability to store and retain carbon.

To capture the full picture, researchers deployed an extensive array of ground-based sensors and towers, complementing the long-running Large-Scale Biosphere-Atmosphere Experiment (LBA) in Amazonia, which is led by Brazil. Mobile instruments and drones have also been used to investigate fire behaviour and sample smoke emissions up close.

Luiz Aragão, scientist at the Brazilian National Institute for Space Research (INPE) and member of the scientific committee of LBA in the Tapajos Forest, said “This campaign is an opportunity for ESA to engage with LBA scientists and also provides new opportunities for LBA to expand and go beyond standard ecological measurements to include novel remote-sensing.”

Martin Wooster, from King’s College London, said, “The in-situ network yields continuous and site-specific measurements. We are now able to measure many properties relating to land–atmosphere exchanges of greenhouse gases, including rates of photosynthesis, and compare observations from undisturbed and degraded forest locations.

“This complements wider airborne ‘snapshots’, and the far broader-scale observations across the entire Amazon from satellite missions such as Copernicus Sentinel-2, Sentinel-3 and Sentinel-5P.”

But the campaign doesn’t stop at ground level. A British Antarctic Survey Twin Otter research aircraft has completed multiple flights over the region, sampling atmospheric greenhouse gases and pollutants, and capturing how fires reshape the landscape from above.

ESA Campaign Coordinator, Dirk Schuettemeyer, highlighted, “The flights mark a significant milestone, as it’s the first time Brazil has granted a foreign remote-sensing aircraft permission to operate in the Amazon since NASA’s landmark SCAR-B campaign in the mid-1990s.

“This new activity is a tangible outcome of ongoing cooperation between ESA, Brazil’s National Institute for Space Research and the Brazilian Space Agency.”

Explaining the value of the data collected and the research to follow, ESA’s Head of Actionable Climate Information Section, Clement Albergel, said, “Accurately representing the pace and scale of greenhouse gas emissions is central to climate modelling. These targeted observations give us crucial insight into the Amazon’s carbon dynamics – what’s happening now, how close we may be to major shifts and what actions are needed.

Dr Schuettemeyer added, “The new field data will also help validate measurements from existing satellites and prepare for new missions, including ESA’s Earth Explorer FLEX mission which is set to launch next year.”

Researchers are now processing the vast ‘data haul’. Once quality checks are complete, the dataset will be made freely available. Upcoming phases of the project will bring scientists and climate modellers together to ensure the findings translate into improved predictions and, ultimately, more effective climate action.